How is Botulax Injected | Procedure Steps, Injection Sites, and Techniques

Botulax injections must be performed by professional doctors. Use 0.9% physiological saline for dilution, paired with 30G ultra-fine to reduce pain. For multi-point injections such as forehead lines and crow’s feet, the common dosage for each point is 2 – 5 units. Effects appear 7 – 14 days after surgery and last for 3 – 6 months. Be sure to choose a regular institution to ensure medical safety.

Procedure Steps

The standard injection process for Botulax is divided into three stages: preparation, marking, and injection. Clinically, 0.9% preservative-free physiological saline is usually used, diluted according to a 100U:2.5ml ratio, so that each 0.1ml contains 4U of solution. The operation uses 30G or 31G , and a multi-point injection method (such as the 5-point method) is adopted for areas like glabellar lines, with the dosage for each point controlled at 2-5U. The injection depth must be adjusted according to the target muscle; for example, the frontal muscle requires a depth of 2-3mm subcutaneous, while the masseter muscle requires vertical insertion. Lying flat is strictly prohibited within 4 hours after the procedure.

Solution Preparation & Dilution Standards

Before starting the preparation, the operator needs to check the integrity of the bottle cap and verify the specification label of 100 Units or 200 Units. The operating environment must be maintained in a sterile state, with 0.9% preservative-free sodium chloride injection (physiological saline), 1ml tuberculin, or U-100 insulin prepared. When opening the cap, wipe the rubber stopper with an alcohol swab. Due to the vacuum state inside the, when the pierces the rubber stopper, the physiological saline will be automatically sucked in. If it is found that the liquid is not sucked in, it indicates that the may have leaked air, the activity cannot be guaranteed, and it should be discarded. The following are common dilution ratios and corresponding unit quantification data based on 100 Units Botulax:

• Dilute with 1.0 ml of physiological saline: each 0.1 ml contains 10 Units of solution. This high-concentration ratio is usually used for large muscle tissues such as the masseter and gastrocnemius muscles, aiming to concentrate the solution locally and reduce diffusion to surrounding non-target muscles.
• Dilute with 2.0 ml of physiological saline: each 0.1 ml contains 5 Units of solution. This is very common when dealing with horizontal forehead lines and glabellar lines, providing a good balance that ensures concentration and facilitates dose calculation.
• Dilute with 2.5 ml of physiological saline: each 0.1 ml contains 4 Units of solution. This is currently a very popular international dilution standard because it allows the operator to perform extremely precise adjustments with 1 unit (0.025 ml) as the minimum step, suitable for fine facial micro-sculpting.
• Dilute with 5.0 ml of physiological saline: each 0.1 ml contains 2 Units of solution. This low-concentration, large-volume plan is more common in micro-droplet injection techniques (Mesobotox), used to improve skin texture or reduce sweat gland secretion.

When injecting physiological saline into the, the tip should point at the inner wall of the glass, allowing the liquid to slide down slowly along the wall rather than spraying violently against the drug powder at the bottom. This method prevents the generation of excessive bubbles, as violent physical impact and bubble formation will cause the protein molecular structure of Type A botulinum toxin to break or denature. After the injection is completed, the should not be shaken violently. The correct way is to place the flat and roll it gently between the palms, or let it stand for 1 to 2 minutes until the powder is completely dissolved. The dissolved liquid should be transparent, colorless, and without suspended matter. If there is any turbidity or discoloration, the solution cannot be used for injection. It is usually recommended to use a 31G or 32G insulin with its own. This integrated design eliminates the “dead space volume” at the connection between the and the tube. When injecting multiple points in sections, the solution remaining in the dead space will cause the actual units injected to be lower than the calculated value. If operating at a 2.5 ml dilution ratio and using a 1 ml with scale marks, every 10 marks (0.1 ml) represents 4 units. When drawing the solution, the operator should pull the plunger slowly to avoid generating negative pressure bubbles. After drawing, gently tap the to discharge the air at the top. Clinical studies show that when injecting equal units of Botulax, using less diluent (high concentration) produces an action area with a radius of approximately 5mm to 8mm. If the amount of diluent is increased (low concentration), the action area will expand accordingly, and the radius may reach more than 1.5cm. In areas with complex anatomical structures, such as around the eye sockets, using a high-concentration, small-volume ratio can reduce the risk of the solution flowing to the levator palpebrae superioris muscle and causing ptosis. In the larger frontal muscle area, appropriately reducing the concentration helps the solution distribute more evenly among the muscle fibers, making expressions look more natural. According to pharmacopoeia standards, it is recommended to use it within 24 hours after preparation. Although in a refrigerated environment of 2°C to 8°C, the solution can still maintain high biological activity within 3 to 7 days, the efficacy will gradually decay over time. If the solution is left at room temperature (exceeding 25°C) for more than 4 hours, its potency may undergo uncontrollable fluctuations. It is strictly forbidden to put the diluted solution in the freezer, because the formation of ice crystals will permanently destroy the tertiary protein structure of the toxin, resulting in complete loss of efficacy. In actual operation, different anatomical levels of different parts also have different requirements for solution volume. For areas with thin skin, such as around the eyes, the volume of the injection point is usually controlled within 0.05 ml to prevent local obvious skin papules. For parts with thick muscles and large range of motion, such as around the mouth or neck, it is necessary to flexibly adjust the dilution ratio in combination with the subject’s muscle strength.

Pre-op Marking & Depth Control

The operator will ask the subject to make maximum facial expressions in a seated position, such as frowning hard, raising eyebrows, or closing eyes tightly. By observing the positions of skin folds formed when muscles contract, use a disposable sterile marking pen to mark the points where muscle strength is strongest. When marking, a ruler must be used to measure specific anatomical boundaries. For example, when treating crow’s feet, the marking position should be at least 1.5cm to 2.0cm away from the Lateral Canthus to avoid the solution diffusing to the muscles that control eye movement. The spacing between marking points is usually maintained at 1.5cm, forming a grid or staggered arrangement. The oil on the skin surface should be wiped clean with alcohol in advance, otherwise the marking lines are easy to blur during the disinfection process.

All injection markings should be finalized while the subject’s muscles are completely relaxed. If the subject has facial asymmetry, the point distribution and solution allocation on the left and right sides should be asymmetrically adjusted according to the degree of muscle hypertrophy.

A 5-point method is adopted for marking Glabellar Lines. One point is located in the Procerus muscle, and the other 4 points are respectively located in the Corrugator Supercilii muscles on both sides. When injecting the procerus muscle, the enters vertically at 90 degrees, and the insertion depth is usually between 6mm to 8mm to ensure the solution is precisely delivered to the thick muscle belly. The insertion for the corrugator muscle is divided into medial and lateral points: the medial point is near the brow head, with a deeper insertion depth of about 5mm; The lateral point needs to be significantly shallower, with the insertion depth controlled at 2mm to 3mm, using a 30-degree oblique puncture method to enter the subcutaneous tissue or superficial muscle, aiming to avoid the nerves and vessels near the supraorbital foramen.

In the operation of the forehead area, the safe zone is defined as the range above 2.0cm from the upper margin of the eyebrow. This distance quantification standard is to prevent the paralysis of the lower part of the frontalis muscle from leading to severe brow ptosis.

Markings for Forehead Lines are usually arranged horizontally, but also need to be adjusted according to the width of the frontalis muscle. If the frontalis muscle strength is strong and the area is wide, a staggered marking method with two rows can be adopted. Insertion depth is a very sensitive parameter in the forehead. The frontalis muscle is a thin sheet muscle, and the insertion depth is usually maintained at 2mm to 3mm. After the enters the skin, the operator can feel a slight disappearance of resistance, indicating that the tip has penetrated the dermis and reached the muscle surface. The injection angle is suggested to be maintained at 15 degrees to 30 degrees. This superficial injection technique can allow the solution to diffuse evenly in the wide frontalis muscle fibers. The injection volume for each point should be limited to about 0.05ml, forming a small papule, and then the solution will be automatically penetrated and absorbed within a few minutes. If the insertion is too deep and directly touches the frontal periosteum, the subject will feel obvious stinging, and it is easy to cause subperiosteal hematoma.

The injection for crow’s feet around the eyes must adopt a very superficial subcutaneous technique. The tip only needs to enter the skin by 1.5mm to 2.0ml, and transparent hemispherical papules should be clearly seen on the skin surface during injection.

When treating Masseter Hypertrophy, the depth control is completely different. The operator will ask the subject to clench their teeth to find the anterior and posterior margins of the masseter muscle. Markings are usually distributed within a triangle, with the lowest point about 1.0cm away from the edge of the mandible. The insertion adopts 90-degree vertical entry. For adult subjects, the insertion depth is usually 10mm to 12mm. When advancing the, the subject will successively feel skin resistance, the softness of the subcutaneous fat layer, and the tight holding sensation after entering the muscle tissue. The masseter muscle is a deep, large muscle, and the solution needs to be distributed in the middle and deep layers of the muscle to exert maximum effectiveness. To ensure a uniform effect, 3 to 5 points are usually distributed on each side, and the dose of each point is usually 2 to 3 times that of the facial wrinkle removal points. Because the masseter area is rich in blood vessels, the should be withdrawn quickly and followed immediately by local vertical pressure to prevent the formation of deep hematomas.

For the marking of Nefertiti Lift, it should be arranged along a distance of one finger width below the lower margin of the mandible. The depth of the entering the platysma muscle should not exceed 2mm, because the platysma is a very thin skin muscle, and too deep an injection will accidentally injure the deep swallowing-related muscles.

In the treatment of Bunny Lines, markings are located on the Nasalis muscles on both sides of the bridge of the nose. Since the skin here is extremely thin and directly attached to the nasal bone below, the insertion angle should be extremely flat, about 10 degrees to 15 degrees, and the depth is only about 1mm. If the is inserted too deep and touches the nasal mucosa, it will cause the subject to have a strong sneezing reflex or nasal soreness. The Botulax dose for each point needs to be strictly controlled at 1 to 2 units. Excessive or too deep injection may affect the lifting function of the upper lip, leading to stiff expressions when smiling.

The specification of the has a direct feedback on depth perception. When using 32G ultra-fine, the sense of resistance is weak, and the operator needs to judge whether the correct anatomical level has been reached through the scale on the and the micro-sensory feedback of the fingertips.

The operator’s non-injecting hand usually gently tightens the subject’s skin, making it easier for the to penetrate the epidermis and reducing depth deviation caused by skin sliding. In some areas with complex anatomical structures, such as Perioral Lines, the depth must be limited to the deep dermis or superficial muscle layer of 1mm to 1.5mm. Because the orbicularis oris muscle is extremely sensitive to the solution, marking positions should be 3mm to 5mm away from the vermilion border. If the depth exceeds 2mm, the solution may affect the subject’s functions of pronunciation, blowing, or using a straw.

Immediate Post-op Care

The initial 4 hours after the Botulax injection is the physiological window period for the solution to be positioned within the target muscle. After leaving the clinic, the subject must keep the head upright, and is strictly forbidden to lie flat, lie on the side, or bend forward significantly (such as tying shoelaces or reading with the head down). The physiological basis for this posture limitation is that Botulax is a Type A botulinum toxin with a molecular weight of approximately 900kDa, which needs a certain amount of time to bind with the receptors of nerve endings after entering the muscle tissue. If a significant posture change occurs during this period, gravity may induce physical displacement of the solution that has not yet fully bound. Once the solution crosses the anatomical boundary and diffuses into non-target muscles, such as the levator palpebrae superioris, it will trigger adverse reactions such as ptosis. Clinical observations show that maintaining an upright posture for 240 minutes can reduce the probability of unintended diffusion by more than 80%.

• Injection points are strictly forbidden to be squeezed, rubbed, or massaged within 6 hours after surgery. Physical pressure will significantly increase the fluid pressure in the subcutaneous tissue, causing the diffusion radius of the solution between muscle fibers to expand from the normal 5mm-10mm to more than 20mm.
• High-intensity aerobic and anaerobic exercises such as jogging, swimming, or strength training should be avoided within 24 hours after surgery. The increased heart rate and accelerated blood flow brought by strenuous exercise will shorten the residence time of the solution in local tissues, causing some active ingredients to be metabolized by systemic circulation before they take effect.
• It is recommended to use a higher pillow and take a supine position when falling asleep to prevent the face from being compressed during sleep. If the injection area is compressed due to sleeping on the side during the first night after surgery, local asymmetrical edema may appear the next morning.

The integrity of the skin surface is usually initially repaired through platelet aggregation within 15 to 30 minutes after the is removed. However, within 24 hours after surgery, the injection area should avoid contact with untreated tap water or skin care products containing complex chemical components as much as possible. It is suggested that the subject clean the face 4 to 6 hours after the injection is completed, and must use room-temperature water of 20°C to 25°C with a mild amino acid cleanser. Irritating chemical components such as alcohol, fruit acid, salicylic acid, or high-concentration vitamin C should not be applied around the entry points within 3 days to prevent inducing contact dermatitis or chemical irritation. For subjects who are used to using cosmetics, it is recommended to apply base makeup 24 hours after surgery and ensure that makeup tools are strictly disinfected.

• Avoid smoking and alcohol for at least 3 to 5 days. Ethanol and its metabolite acetaldehyde have the effect of dilating peripheral blood vessels, which will increase the risk of ecchymosis at the injection site and may interfere with the repair process of nerve endings.
• Stop taking medications or dietary supplements with blood-activating functions, such as Aspirin, Warfarin, Vitamin E, or Ginkgo biloba extract. These substances will prolong coagulation time and expand tiny bleeding points under the injection points into visible purple spots.
• Washing movements should be gentle. When cleaning the injection area, take the method of dot-painting and pressing rather than circular rubbing to ensure the stability of the solution at the receptor binding points.

Within 7 days after the injection, subjects should avoid going to saunas, steam baths, or taking hot baths exceeding 38°C. Botulinum toxin is essentially a temperature-sensitive protein. Elevated environmental temperature will cause accelerated local tissue metabolism, which will not only weaken the protein activity of Botulax but may also shorten its clinical maintenance cycle. For subjects receiving jawline (masseter) injections, they should reduce the consumption of hard and tough foods, such as nuts or hard meat, within 2 weeks. Since the disuse atrophy of the masseter muscle takes time, premature heavy-load chewing exercise will offset the muscle relaxation effect brought by the drug, leading to a discount on the final shaping effect.

• Within 1 hour after the injection, it is recommended to consciously perform contraction movements of the target muscles. For example, subjects for glabellar lines can repeat frowning several times every 5 minutes. This active contraction can increase the uptake rate of the solution by nerve endings.
• Observe local reactions. A slight redness, swelling, or itching of 1mm-2mm at the injection point is normal and usually subsides on its own within 2 to 3 hours. It is strictly forbidden to apply any anti-itch ointment yourself, especially steroid medications containing corticosteroids.
• Avoid receiving photoelectric beauty treatments such as facial laser, radiofrequency, or intense pulsed light. The thermal effect generated by photoelectric treatment will penetrate deep into the muscle layer and directly destroy the molecular chain structure of Botulax. It is recommended that there be at least a 14-day interval between the two types of treatments.

The evaluation of the final effect should be set at the 14th day after surgery. After Botulax enters the tissue, it takes about 3 to 7 days to start showing a decline in muscle tension, and the peak of efficacy usually appears at about two weeks. Subjects should not rush for a second touch-up during this period because the early effect is not obvious. Too frequent injections will increase the risk of neutralizing antibodies in the serum, leading to immune drug resistance in subsequent treatments. If there is still obvious facial asymmetry after two weeks, you should return to the clinic for precise dose correction. Establishing a complete post-op log, recording the daily expression recovery and whether there are symptoms such as headache and double vision, is of high reference value for long-term tracking of treatment effects.

• If severe headache, blurred vision, or difficulty swallowing occurs, the subject must contact the medical institution immediately. Although the incidence of these side effects at standard doses is lower than 1%, they need to be monitored as a safety red line.
• Formulation of follow-up plans. Usually, online or offline follow-up visits are conducted on the 14th day to record photos for comparison with the pre-op (Before) baseline data.
• Management of psychological expectations. Clearly inform the subject that the effect of botulinum toxin is temporary, usually lasting for 4 to 6 months. In the 3rd month when the efficacy gradually weakens, you can start to book the next injection plan to maintain the smooth state of the face.

Injection Sites

The clinical injection points of Botulax are precisely distributed in more than 15 anatomical regions of the face and neck. For the Glabellar Complex, the standard operation is to distribute 5 injection points in the corrugator and procerus muscles, with a total dose of 20U; For crow’s feet around the eyes, 3-4 points are set on each side, with a point distance of 1cm and a distance from the orbital margin of at least 1.5cm to prevent diffusion. Masseter injection usually adopts an equidistant distribution of 3-4 points on each side, with a vertical insertion depth controlled at 10-15mm, ensuring the solution covers the lower 1/3 of the muscle where the motor endplates are most concentrated.

Upper Face

When operating Botulax injections on the upper face, it mainly involves four muscle groups: the frontalis muscle, the corrugator muscle, the procerus muscle, and the orbicularis oculi muscle. The total injection amount in this part is usually controlled between 30 to 60 Units, depending on the thickness and activity intensity of the muscles. The clinically common dilution standard is to dissolve 100 units of lyophilized powder with 2.5 ml of 0.9% sodium chloride solution, so that each 0.1 ml of liquid contains 4 units of solution. Using 30G or 31G 8mm fine can reduce the resistance during insertion and improve the precision of solution distribution.

Forehead Area

For horizontal lines in the forehead area, the target muscle is the frontalis muscle. The frontalis is a thin and wide muscle responsible for lifting the eyebrows. When injecting in the forehead, the points must be maintained at least 2 centimeters (about two fingers wide) above the upper margin of the eyebrow. If the injection point is too low, the solution will diffuse into the lower part of the frontalis muscle through tissue gaps, leading to eyebrow drooping or a heavy eyelid sensation. Usually, 4 to 8 injection points are set in the forehead, staggered in two rows, with a horizontal distance between points of 1.5 to 2 centimeters. The injection dose for each point is usually 1 to 2 units, with the insertion depth controlled at 2 to 3 millimeters, that is, the tip enters the subcutaneous tissue to reach the muscle surface. The fibers of the frontalis muscle are vertically oriented, so the horizontal diffusion range of the solution in the muscle is a circular area with a radius of about 1 centimeter.

Glabellar Area

This involves 1 procerus point and 4 corrugator points. The procerus is located directly above the nasal bridge. The injection point is set at the center point of the connection between the inner sides of the two eyebrows, and the insertion depth is relatively deep, usually requiring vertical entry of 5 to 6 millimeters. The corrugator muscle is divided into medial and lateral points. The medial point is located about 0.5 centimeters above the medial corner of the supraorbital margin, where the muscle is thick and requires deep vertical injection of 4 to 6 units. The lateral point is located vertically above the pupillary midline, close to the middle of the eyebrow. Here the muscle becomes shallower, the insertion depth should be halved, and the dose should also be reduced to 2 to 3 units to avoid the levator palpebrae superioris muscle and prevent the side effect of ptosis.

Around the Eyes

The skin here is very thin, with an average thickness of only about 0.5 millimeters, and it is closely attached to the bones and blood vessels below. When injecting around the eyes, it must be ensured that all points are at least 1 centimeter outside the orbital bone margin. The standard operation is to distribute 3 points in a fan shape outside the corner of the eye. The first point is on the horizontal line of the eye corner, and the other two points are respectively about 1 centimeter above and below it.

• Injection Angle: The is at an angle of 15 to 30 degrees to the skin, pointing obliquely outward to avoid pointing toward the eyeball.
• Injection Depth: Only enter 1 to 2 millimeters subcutaneously, forming a tiny papule.
• Diffusion Control: The dose for each point should not exceed 4 units. Too large a dose will increase the risk of the solution penetrating into the eye socket and hindering the activity of extraocular muscles.
• Vessel Avoidance: There is a dense capillary network around the eyes. Before insertion, observe the skin surface under strong light to avoid visible blue-purple blood vessels.

The layers of the upper face skin from outside to inside are the epidermis, dermis, subcutaneous fat, muscle, and periosteum. In the middle of the forehead, the total thickness is usually between 4 to 6 millimeters. When injecting with a 31G , the push pressure should be kept constant to ensure the precise output of 0.025 ml (i.e., 1 unit). After Botulax enters the tissue, it will rapidly bind to receptors on nerve endings, and its diffusion radius is greatly affected by the dilution concentration. If there is too much diluent, the diffusion diameter of the solution will exceed 2 centimeters, which is easy to cause accidental injury to non-target muscles in the dense glabellar area.

Middle and Lower Face

The total injection volume of the middle and lower face usually fluctuates between 40 to 100 Units depending on the target area. The muscles in this region are mostly expression muscles and are closely related to chewing function, swallowing, and speech expression. Therefore, the injection depth error cannot exceed 1 to 2 millimeters. The standard dilution configuration is still maintained at a concentration of 4 units per 0.1 ml to limit the diffusion radius of the solution in fine muscle groups.

Triangle Zone

The boundary of this triangle zone consists of the connection between the earlobe and the mouth corner, the lower margin of the mandible, and the posterior margin of the mandibular ramus. Injection points are usually distributed in the lower 1/3 region of the masseter muscle because this is where muscle hypertrophy is most obvious and it is far from the parotid duct. Usually, 3 to 5 injection points are set on each side, arranged in a triangle or plum blossom shape, with the distance between points maintained at 1 centimeter. Inject with a 13 millimeter (0.5 inch) using a 90-degree vertical entry directly into the deep layer of the muscle. For a single-sided masseter muscle, the suggested dose is 25 to 50 units, with a total dose of around 50 to 100 units. The solution will start to block the release of acetylcholine from the neuromuscular junction within 7 to 14 days after injection, leading to disuse atrophy of the muscle volume.

Perioral Area

For smoking lines or perioral fine lines, the injection points should be positioned 1 to 2 millimeters above the Vermilion Border, and the dose for each point is strictly controlled at 1 to 2 units. The total dose usually does not exceed 4 to 6 units to prevent situations where water leaks when drinking or there is no power when blowing. The insertion angle adopts a 30-degree oblique puncture, entering only the shallow subcutaneous layer. In improving the “gummy smile,” the target is the levator labii superioris alaeque nasi (LLSAN). The injection point is located about 1 centimeter lateral to the nasal wing, and injecting 2 units per side can effectively inhibit the excessive lifting of the upper lip. The insertion depth needs to reach 4 to 5 millimeters to touch the muscle belly.

DAO and Mentalis

The injection point for the depressor anguli oris (DAO) is located about 1 centimeter below and outside the mouth corner, usually above the mandibular margin. Inject 2 to 4 units per side, aiming to weaken the downward pulling force and make the mouth corner slightly upward in the static state. If the insertion position is too medial, the solution may diffuse into the depressor labii inferioris muscle, leading to a crooked lower lip when speaking. Mentalis injection in the chin area is used to eliminate “orange peel” wrinkles. The injection points are usually selected at 0.5 centimeters on both sides of the chin midline, close to the mandibular tip. Since the mentalis is a deep muscle, the needs to enter vertically for 6 to 8 millimeters, injecting 4 to 5 units per point. For the Nefertiti Lift and neck bands, the focus of injection is on the posterior fibers of the platysma muscle. On the jawline, set an injection point every 1 centimeter, inject 2 units per point, for a total of about 10 to 15 points. For obvious vertical bands in the neck, you need to pinch the muscle with your fingers and insert the every 1.5 to 2 centimeters along the band, with a dose of 2 to 3 units per point. Since the neck skin is extremely thin and the anterior and external jugular veins are distributed below, the injection depth must be limited to within 2 millimeters of the subcutaneous tissue to avoid entering deep throat structures or large vessels.

Injection Safety Red Line

For example, in masseter injection, it is strictly forbidden to cross the lower margin of the zygomatic arch to prevent the solution from affecting the buccinator muscle and leading to chewing weakness. In perioral injection, the solution distribution on the left and right sides must maintain an absolute symmetry of 1:1. Any error exceeding 0.5 units may show obvious asymmetry in dynamic expressions. The diffusion radius of Botulax in these areas is greatly affected by the frequency of muscle contraction, so strenuous chewing or facial massage should be avoided within 24 hours after surgery.

Insertion Angle and Dose Distribution

For subjects receiving injections for the first time, it is usually recommended to adopt the “low dose start” principle, which means operating at the lower limit of the standard suggested value and supplementing after 14 days according to the degree of muscle relaxation. By using a 32G ultra-fine , the pressure during injection can be controlled within the minimum range, thereby effectively reducing the unintended leakage of the solution to surrounding non-target muscle tissues.

Muscle Movement Alignment

Studies show that in facial expression muscles, motor endplates are not uniformly distributed but are concentrated in specific areas of the muscle belly, commonly referred to as “motor points.” For flat muscles like the frontalis, the motor point is usually located in the middle segment of the muscle, while in thick muscles such as the masseter, the motor point is hidden in the middle and lower 1/3 region of the muscle belly.

Experimental data indicate that when the injection site deviates from the motor point by more than 1 centimeter, the blocking efficiency of the drug on the motor unit will drop by 30% to 50%. This is because Type A botulinum toxin searches for nerve endings through diffusion, and its concentration in the tissue decays exponentially with distance.

Taking 100 units of Botulax diluted with 2.5 ml of physiological saline as an example, the ideal diffusion radius of each 0.1 ml of liquid in the muscle tissue is about 10 mm. To achieve complete coverage of motor units, the horizontal distance between injection points should be maintained between 1.5 cm to 2 cm. There are differences in the alignment plans of insertion angle and depth for motor units at different depths. In the upper face, the motor units of the frontalis muscle are distributed in a layer 2 to 4 millimeters from the skin surface. Using a 30G at a 45-degree angle, when the resistance is felt to decrease slightly, the tip has usually penetrated the superficial fascia and reached the muscle layer. For the masseter muscle, because its thickness is usually between 10 to 15 millimeters and it contains multiple muscle bundles, a vertical 90-degree entry must be used to distribute the solution evenly in the superficial, middle, and deep layers.

Clinical anatomical studies show that the nerve entry points of the masseter muscle are mainly distributed in a rectangular area 2 cm posterior to the anterior margin of the mandibular ramus and 2 to 5 cm above the lower margin of the mandible. Performing 3 to 5 equidistant injections in this area can maximize the coverage of the motor endplate density area of the masseter muscle.

Before injection, the subject is asked to perform maximum muscle contraction (such as frowning hard or clenching teeth), and the “point” where the muscle contraction is strongest and the volume is largest is determined through palpation. This point is the most active area of that motor unit. If it is observed that the movement range of the muscle on one side is significantly greater than that on the other side, it indicates that the number of motor units in that area is larger or the nerve conduction is more active. At this time, the dose at that site needs to be correspondingly increased by 15% to 20% to achieve a balance of motor tension on both sides.

When dealing with the glabellar complex, the motor units of the corrugator muscle present an oblique course. The injection depth of the medial point needs to reach 7 to 8 millimeters, while when moving laterally, because the muscle gradually becomes shallower and merges with the skin dermis, the injection depth needs to be gradually adjusted to 3 to 5 millimeters.

Too large a single-point injection volume (for example, exceeding 0.1 ml) will increase the hydrostatic pressure in the tissue, causing the solution to undergo unintended longitudinal flow along the fascia gaps, thereby accidentally injuring non-target motor units. Using micro-injection technology to control the single-point dose between 0.025 ml (i.e., 1 unit) to 0.05 ml (i.e., 2 units) can use the natural physical barrier of the tissue to lock the toxin in a specific muscle movement plane. For very thin muscles such as the orbicularis oculi, motor units are almost closely attached to the subcutaneous tissue. At this time, the alignment focus is to avoid the diffusion of the solution into the deep extraocular muscles. The injection should only enter for 1 to 2 millimeters, producing a visible tiny protrusion (Wheal).

For the platysma bands of the lower and middle face, motor units are distributed along the long axis of the muscle. During injection, the muscle band needs to be pinched, and the is inserted parallel to the muscle fibers, injecting once every 2 cm. This linear arrangement along the chain of motor units is more effective in relaxing the vertical bands of the neck than random point injections.

In the process of operation, avoiding blood vessel branches is also an element to ensure the alignment effect of motor units. The formation of a hematoma will dilute the local drug concentration and physically block the contact between the toxin and nerve endings. Avoiding visible veins with a diameter of more than 0.5 mm under strong lighting and using cold compresses to constrict small blood vessels can ensure that the solution enters directly into the dry muscle tissue gaps, thereby producing the most direct biochemical reaction with the target motor unit.

Techniques

Botulax injection involves 100U/200U specification agents. The operation is paired with 30G-32G ultra-fine, and 0.9% sodium chloride is routinely used for dilution, with a ratio of 2.5ml/100U to achieve a unit concentration of 4U/0.1ml. Insertion depth is adjusted according to the part: 2mm intradermal for the forehead, and up to 8-10mm for the deep layer of the masseter muscle. The diffusion radius of each injection point needs to be controlled within 1-1.5cm. The amount of medicine pushed at a single point of 0.05ml is precisely controlled through a 1ml to reduce the impact on non-target muscles.

Injection Tools

When performing clinical operations with Botulax, choosing a 1ml capacity low dead volume (LDV) is the basis for ensuring dose precision. Standard 1ml usually have 0.01ml scale units, which allow the operator to perform incremental injections in micro-units of 0.025ml or 0.05ml. Common may leave about 0.07ml to 0.09ml of solution at the seat position. If calculated according to the standard of 2.5ml saline diluting 100U powder, this “dead space” will result in a waste of about 2.8U to 3.6U of medicine. In contrast, LDV reduce the residual amount to below 0.01ml by extending the column at the top of the plunger, significantly improving the utilization rate of high-cost agents. barrels are mostly made of medical-grade polypropylene, and an extremely thin layer of silicone oil is coated inside to ensure that the sliding friction of the plunger during injection is maintained at a constant level between 2N to 5N, avoiding solution gushing due to resistance fluctuations. The selection of specifications is directly related to the puncture resistance and the patient’s pain score. Currently, 30G, 31G, or 32G ultra-fine are the first choice of international standards.

The bevel design of the tip usually adopts Tri-beveled technology, with the inclination angle set between 11 degrees to 13 degrees, aimed at penetrating the stratum corneum with minimum mechanical shear force. lengths are usually divided into four specifications: 4mm, 6mm, 8mm, and 13mm. In the forehead or crow’s feet area, 4mm or 6mm short can prevent the tip from accidentally touching the periosteum and causing severe pain; In the treatment of the thick mandibular masseter muscle, a 13mm is required to penetrate soft tissues that are usually more than 10mm thick. To maintain tip sharpness, if more than 10 injection points are involved in a single treatment, it is recommended to change the because after the tip penetrates the skin 5 times, its metal blade edge deformation will cause the puncture force to rise from the initial 0.5N to more than 1.2N. When drawing 0.9% bacteriostatic saline, 18G or 21G large-bore medicine-drawing are usually used to reduce negative pressure when drawing liquid. The diluent needs to be injected slowly along the inner wall of the Botulax to avoid bubble generation that causes physical denaturation of the protein structure in the 2.5ml liquid environment. The interior of the usually maintains a negative pressure vacuum state of about 2mmHg to 5mmHg. If no vacuum suction is felt during injection, it may indicate that the ‘s sealing is damaged, and the protein activity may have been affected by environmental humidity.

• Digital calipers: Used to measure the thickness difference of bilateral masseter muscles or the precise spacing between forehead injection points, ensuring the error of bilateral symmetry is controlled within 0.5mm.
• Surgical grade marker: Using gentian violet or sterile ink to mark points before injection, preventing missing or overlapping points during multi-point injection. The diameter of each marking point should not exceed 1mm.
• Vibration analgesic: Uses high-frequency vibration of 100Hz to 120Hz to interfere with the transmission of pain signals from nerve endings (gate control theory), providing physical anesthesia at the instant the enters the skin.

Temperature control hardware is the physical boundary to guarantee the activity of Botulax protein. Medical refrigerators need to have dual-way temperature sensors to keep the internal environment constant within the range of 2°C to 8°C, and the temperature fluctuation amplitude shall not exceed ±1.5°C. For diluted solution, the clinical operating table should be equipped with small refrigeration modules or ice-lined devices to ensure that the solution always remains in a low-temperature state within 30 minutes to 60 minutes after being drawn into the. If the environmental temperature exceeds 25°C, the solution that is not injected in time may face about 2% to 5% biological activity attenuation per hour. The choice of anesthesia tools is quantified according to the patient’s tolerance. Topical lidocaine cream (concentration usually 5%) needs to be covered with occlusive tape for 20 to 30 minutes to allow the anesthetic components to penetrate into the subcutaneous depth of 2mm to 3mm. For areas that do not require chemical anesthesia, a -10°C cold compress cycler can be used for 15-second pre-cooling of local skin to constrict capillaries, which can reduce the incidence of post-injection bruising by about 70%.

Level Control and Insertion Angle

The thickness of human face skin in each area differs significantly. For example, the skin thickness at the eyelid is only about 0.5mm, while the total thickness of the skin and subcutaneous tissue in the submandibular area can reach 10mm to 15mm. Standardized injection operations divide facial layers into Dermis, Subcutaneous tissue, Muscle, and the deep Periosteum. For the treatment of most dynamic wrinkles, the solution must be accurately delivered to the neuromuscular junctions between muscle fibers, namely the Motor endplate zones, which are usually distributed in the middle of the muscle belly. When dealing with large functional muscles such as the masseter or gastrocnemius, a 90-degree vertical insertion method is usually adopted. For adult males, the thickness of the masseter muscle in the resting state is usually between 12mm to 15mm, and the operator needs to use a 13mm 30G . The insertion depth needs to be controlled at about 10mm to ensure the tip passes through the superficial fascia and enters the deep part of the muscle belly. If the insertion depth is less than 5mm, the solution will remain in the superficial layer, which may lead to the drug entering the parotid gland parenchyma through diffusion and triggering side effects such as dry mouth. In the gastrocnemius injection of the foot, the vertical insertion depth can reach 15mm to 20mm to adapt to thicker muscle bundles and ensure that 100U to 200U of solution can evenly cover the motor endplate distribution area.

For the Frontalis in the forehead area, the insertion angle is usually set at 30 degrees to 45 degrees. The forehead skin thickness is about 2.5mm, with a thin layer of frontalis muscle closely attached below. During injection, the tip bevel should face down, and the insertion depth is about 3mm to 4mm. Since the frontalis is a large flat muscle, the coverage radius of a single-point injection is about 1.5cm, so the operator needs to establish 4 to 8 injection points in the forehead. If the insertion depth exceeds 6mm, the tip may touch the periosteum, causing the patient to feel a physical pain similar to scratching. In the glabellar area, the structure of the corrugator supercilii has a high sense of three-dimensionality. Its starting point is deep in the nasal root and extends outward and upward to the middle of the eyebrow. During operation, the medial point is suggested to adopt 90-degree deep injection, with a depth of about 8mm; the lateral point is changed to 45-degree superficial injection, with the depth reduced to 3mm. This gradient control from deep to shallow is to conform to the physiological course of the muscle on the surface of the frontal bone. The Micro-droplet technique completely abandons deep muscle drug delivery and strictly limits the angle to 10 degrees to 15 degrees. This method usually uses 32G or 33G ultra-fine , with an entry depth of only 1mm to 1.5mm. The target layer is the junction between the deep dermis and the superficial muscle layer. The amount of Botulax solution released at each injection point is extremely small, usually 0.0125ml (equivalent to 0.5U to 1U). Since the solution is located in the superficial layer, its lateral diffusion is limited by connective tissue fiber bundles, and the diffusion radius will shrink to 5mm to 8mm.

• Eye area safety margin control: When dealing with crow’s feet, the insertion point must be located 1cm to 1.5cm from the outer orbital edge. Use a 15-degree oblique entry, with the tip pointing outward. The depth is controlled within 2mm, and vertical entry toward the eyeball is strictly forbidden to prevent the solution from seeping into the eye socket and causing double vision.
• Neck platysma injection parameters: Neck skin is extremely thin and has little subcutaneous fat. When injecting the platysma, the operator needs to pinch the skin with the left hand to form a skin fold, and the enters the center of the skin fold at a 30-degree angle. The insertion depth is about 2mm to 3mm, ensuring the solution acts on the platysma band.
• Resistance feedback identification: During the insertion process, the operator judges the level through the physical resistance transmitted by the. The resistance is greatest when penetrating the stratum corneum, decreases sharply when entering the fat layer, and a slight “breakthrough” sensation occurs when touching the muscle fascia. Once this physical feedback is sensed, the advancement should be stopped immediately and drug pushing should begin.

In 90-degree vertical injection, the solution diffuses in a spherical shape and may leak along the track to the superficial layer under the influence of gravity. Therefore, after the deep injection is completed, it is suggested to keep the tip still for 2 seconds before withdrawing the, and cooperate with vertical pressure. While in 15-degree superficial injection, the solution mainly spreads in a flat shape in the tissue gaps. For patients with high skin laxity, the tissue gap pressure is lower, and the diffusion range of the solution will increase by about 20% compared with tight skin. This means when treating elderly patients, the spacing of injection points should be expanded from the standard 1.5cm to 1.8cm to prevent excessive inhibition of local muscle function due to efficacy overlap. When performing the Nefertiti Lift, the insertion angle needs to be inclined 45 degrees downward along the lower margin of the mandible. The injection depth here needs to be around 3mm, aiming to block the downward pulling force of the platysma muscle on the mandible. Since this area is distributed with important marginal nerves, the precision error of level control must be limited to within 1mm.

Environment and Storage Requirements

In the undiluted lyophilized powder state, Botulax must be stored throughout the process in a constant-temperature refrigerated environment of 2°C to 8°C, or maintained in a frozen state below -5°C under specific long-distance transportation needs. This 900kDa protein complex is extremely sensitive to thermal energy. Once the environmental temperature exceeds 25°C for more than 48 hours, the stability of its molecular chain will undergo irreversible physical changes, leading to a decline in clinical efficacy of about 15% to 20%. In the storage facilities of the clinic, it is recommended to be equipped with a medical-grade refrigerator with dual independent temperature control sensors to ensure that the temperature fluctuation radius in the internal space is controlled within ±1.5°C.

In actual operation, a vacuum state of 2mmHg to 5mmHg is maintained inside the Botulax. This is a physical indicator for judging product integrity. When injecting physiological saline, if the plunger is not guided by automatic suction, it indicates that the ‘s sealing is damaged. At this time, oxygen and humidity in the environment may have penetrated, leading to pre-oxidation and denaturation of protein molecules.

The dilution process of the medicine solution has almost demanding requirements for the physical environment. The operating table should be maintained in a sterile, windless environment of 20°C to 22°C and avoid direct strong ultraviolet radiation. When adding 0.9% preservative-free sodium chloride solution, the operator needs to maintain an extremely slow speed, allowing the saline to slide down along the wall. It is strictly forbidden to spray the liquid directly on the white powder block at the bottom, because the instantaneous hydraulic impact will generate a large number of microbubbles. When diluting 100U specification Botulax, a 2.5ml saline volume is usually used to achieve a standardized concentration of 4 active units per 0.1ml. The diluted is strictly prohibited from any form of shock or shaking, and the solution can only be made uniform through a smooth and slow rotation movement.

Research data show that the activity of Botulax is most stable in the first 24 hours after dilution. Although storing it in a 2°C to 8°C dark environment for up to 4 weeks can still retain most of the efficacy, in order to avoid the risk of microbial contamination and protein degradation clinically, standard operating procedures usually require that the injection be completed within 4 to 6 hours.

For humidity control of the clinical environment, it is recommended to keep it between 40% to 60%. Excessive humidity may increase the generation of condensation on the outside of the, thereby interfering with the operator’s visual judgment of the 0.01ml scale on the 1ml . During the process of drawing the solution into the 30G, if the solution is exposed to room temperature for more than 15 minutes, the efficacy will start to undergo a slight attenuation due to thermodynamic effects. Therefore, in the continuous operation of large clinics, it is recommended to temporarily place the that have completed suction in a tray containing ice lining. The extension of this cold chain can ensure that from the to the subcutaneous tissue, Botulax always remains in the ideal temperature zone below 10°C throughout the physical path.

The impact of environmental light on Botulax cannot be ignored. This toxin has absorption characteristics for specific wavelengths of ultraviolet rays. Long-term exposure to strong surgical lights will lead to protein cross-linking. In the process of preparing the solution, the exposure time of the to strong light should be as short as possible, or a brown light-shielding cover should be used for physical covering to maintain the integrity of its molecular structure.

In cold chain logistics, the Botulax packaging box should be filled with high-density polyurethane buffering materials to absorb high-frequency vibrations of 50Hz to 500Hz generated by transportation vehicles. Violent physical displacement will cause friction between the lyophilized powder and the wall to generate static electricity, which in turn affects the dissolution rate of the powder during dilution. For Botulax that has already been diluted into a liquid state, long-distance secondary transportation is strictly prohibited. The denaturation speed of liquid molecules in a shaking environment is more than 10 times that in the powder state. If it must be moved between different treatment rooms, a hand-held stable refrigeration box should be used and kept horizontal. All,, and empty that have been in contact with Botulax solution must be treated at high temperature in a 121°C autoclave for no less than 20 minutes. This treatment can completely destroy the biological activity of botulinum toxin and convert it into harmless amino acid fragments. In cases where heat treatment cannot be carried out immediately, a 0.5% sodium hypochlorite solution can be used for immersion disinfection. The immersion time must exceed 30 minutes to ensure that the biological safety of the laboratory environment conforms to international prevailing standards.

Regarding the cold chain log recording of the Botulax 100U specification, it is recommended to perform manual or automatic temperature calibration once every 4 hours. When a power failure of the refrigerator is found or the temperature exceeds 10°C, the exposure time should be recorded. If the cumulative exposure time exceeds 4 hours, the clinical expected effect of the batch of medicine should be re-evaluated, or its priority for use in non-precision injection areas (such as the thigh part) should be reduced.