Chemocain-A is a local anaesthetic for use in infiltration anaesthesia and nerve blocks.
This is a sterile, aqueous solution that contains a local anaesthetic agent- lidocaine HCl with epinephrine (adrenaline). Lidocaine is a local anaesthetic of the amide type. It stabilizes the neuronal membrane by inhibiting the ionic fluxes required for the initiation and conduction of impulses, thereby effecting local anaesthetic action. Lidocaine has a rapid onset of action and intermediate duration of action. The speed of onset and duration of action are increased by the addition of vasoconstrictor-epinephrine (adrenaline) and absorption into circulation from the site of injection is reduced. The duration of action is approximately one and-a-half to two hours with epinephrine (adrenaline).
In estimating the safe dosage of this drug, it is important to take account of the rate at which it is absorbed and excreted as well as its potency. The patient's age, weight, physique and clinical condition, the degree of vascularity of the area to which the drug is to be applied, and the duration of administration are other factors which must be taken into account. The dosage is adjusted according to the response of the patient and site of administration. The lowest concentration and smallest dose producing the required effect should be given. Adults : For healthy adults, the individual maximum recommended dose should not exceed 7 mg/kg of body weight and in general it is recommended that the maximum total dose not exceed 500 mg. Children and elderly or debilitated patients : require smaller doses, commensurate with age and physical condition. Dosages in children should be reduced, commensurate with age, body-weight and physical condition. The following doses have been recommended for individual local anaesthetic procedures in the USA: For percutaneous infiltration anaesthesia: 5 to 300 mg (1 to 60 mL of a 0.5% solution or 0.5 to 30 mL of a 1% solution). The dosage in peripheral nerve block depends on the route of administration. For brachial plexus block 225 to 300 mg (15 to 20 mL) as a 1.5% solution is used; for intercostal nerve block 30 mg (3 mL) is given as a 1% solution; for paracervical block a 1% solution is used in a dose of 100 mg (10 mL) on each side, repeated not more frequently than every 90 minutes; for paravertebral block a 1% solution may be used in doses of 30 to 50 mg (3 to 5 mL); a 1% solution is recommended for pudendal block in doses of 100 mg (10 mL) on each side; for retrobulbar block a 4% solution may be used in doses of 120 to 200 mg (3 to 5 mL) For sympathetic nerve block a 1% solution is recommended; doses are 50 mg (5 mL) for cervical block and 50 to 100 mg (5 to 10 mL) for lumbar block. For epidural anaesthesia 2 to 3 mL of solution is needed for each dermatome to be anaesthetised but usual total doses and recommended concentrations are: lumbar epidural 250 to 300 mg (25 to 30 mL) as a 1% solution for analgesia and 225 to 300 mg (15 to 20 mL) as a 1.5% solution or 200 to 300 mg (10 to 15 mL) as a 2% solution for anaesthesia, and for thoracic epidural a 1% solution may be used at doses of 200 to 300 mg (20 to 30 mL). In obstetric caudal analgesia 200 to 300 mg (20 to 30 mL) is used as a 1% solution and in surgical caudal anaesthesia a 1.5% solution may be used in doses of 225 to 300 mg (15 to 20 mL). For continuous epidural anaesthesia, the maximum doses should not be repeated more frequently than every 90 minutes. A hyperbaric solution of 1.5% or 5% lidocaine hydrochloride in glucose 7.5% solution is available for spinal anaesthesia; then epinephrine (adrenaline) should not be used. Doses of up to 50 mg (1 mL) as a 5% solution and 9 to 15 mg (0.6 to 1 mL) as a 1.5% solution have been used during labour for a normal vaginal delivery. Up to 75 mg (1.5 mL) as the 5% solution has been used for caesarean section and 75 to 100 mg (1.5 to 2 mL) for other surgical procedures.
Always consult a registered doctor before taking any medicine. This information is for general knowledge only.
In common with other local anaesthetics, adverse reactions are rare and are usually the result of excessively high blood concentrations due to inadvertent intravascular injection, excessive dosage, rapid absorption or occasionally to hypersensitivity, idiosyncracy or diminished tolerance on the part of the patient. In such circumstances systemic effects occur involving the CNS and/or the cardiovascular system. CNS reactions are excitatory and/or depressant, and may be characterized by nervousness, dizziness, blurred vision and tremors, followed by drowsiness, convulsions, unconsciousness and possibly respiratory arrest. The excitatory reactions may be very brief or may not occur at all, in which case the first manifestations of toxicity may be drowsiness, merging into unconsciousness and respiratory arrest. Cardiovascular reactions are hypotension, myocardial depression, bradycardia and possibly cardiac arrest. Allergic reactions are extremely rare. They may be characterized by cutaneous lesions, urticaria, oedema or anaphylactoid reactions.
Known hypersensitivity to anesthetics of the amide type. It should not be injected into tissues supplied by end arteries, for example, fingers and toes, ears, the nose, and the penis. The intense vasoconstriction produced by epinephrine (adrenaline) may result in gangrene. For the same reason, it should be avoided in solutions injected intracutaneously. Since epinephrine (adrenaline) also is absorbed into the circulation, its use should be avoided in those for whom adrenergic stimulation is undesirable.
It exhibits interaction with monoamine oxidase inhibitors, tricyclic antidepressants, phenothiazines, butyrophenones, vasopressor drugs (for the treatment of hypotension related to obstetric blocks) and ergot-type oxytocic drugs.
This injection for infiltration and nerve block should be employed only by clinicians who are well versed in diagnosis and management of dose-related toxicity. The safety and effectiveness of lidocaine depend on proper dosage, correct technique, adequate precautions, and readiness for emergencies. Standard text books should be consulted for specific techniques and precautions for various regional anaesthetic procedures. Resuscitative equipment, oxygen, and other resuscitative drugs should be available for immediate use. It should be used cautiously in patients with epilepsy, impaired cardiac conduction, impaired respiratory function and in patients with impaired hepatic function, if the dose or site of administration is likely to result in high blood levels. The lowest dosage that results in effective anaesthesia should be used to avoid high plasma levels and serious adverse effects. The effect of local anaesthetics may be reduced if an injection is made into an inflamed or infected area. It should be used with caution in patients with hypertension, cardiac disease, cerebrovascular insufficiency, thyrotoxicosis, in patients taking tricyclic antidepressants, MAOI's or receiving potent general anaesthetic agents. Careful and constant monitoring of cardiovascular and respiratory vital signs and the patient's state of consciousness should be accomplished after each local anaesthetic injection.