Marcain Dosage/Direction for Use

As with all local anaesthetics, the dosage varies and depends upon the area to be anaesthetised, the vascularity of the tissues, the number of neuronal segments to be blocked, the depth of anaesthesia and degree of muscle relaxation required, individual tolerance, the technique of anaesthesia and the physical condition of the patient.
The lowest dosage that results in effective anaesthesia should be used. In general, surgical anaesthesia requires the use of higher concentrations and doses than those required for analgesia. The volume of the drug used will affect the extent of spread of anaesthesia.
Marcain is intended for single use only. Any solution remaining from an opened container should be discarded.
The following table is a guide to dosage. The clinician's experience and knowledge of the patient's physical status are of importance in deciding the dose. Experience to date indicates that 400 mg administered over 24 hrs is well tolerated in average adults (see table).

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Recommended Doses: Tolerability varies widely between patients and toxic effects may occur after any local anaesthetic procedure. Careful observation of the patient must therefore be maintained. It is recommended that the dose of bupivacaine at any time should not exceed 2 mg/kg. However, the dose administered must be tailored to the individual patient and procedure, and the maximum dose quoted here should be used as a guide only.
Injection: Injection of repeated doses of bupivacaine may cause significant increase in blood levels with each repeated dose, due to accumulation of the drug or its metabolites or due to slow metabolic degradation. The rapid injection of a large volume of local anaesthetic solution should be avoided and fractional doses should be used when feasible. For most indications, the duration of Marcain is such that a single dose is sufficient.
Hypotension: During thoracic, lumbar and caudal epidural anaesthesia/analgesia, a marked fall in blood pressure and/or intercostal paralysis may be seen, possibly due to the use of excessive doses, improper positioning of the patient or accidental disposition of the anaesthetic within the subarachnoid space. Hypotension and bradycardia may occur as a result of sympathetic blockade.
Test Dose: For epidural anaesthesia, a test dose of 3-5 mL of a local anaesthetic solution, preferably containing up to 15 mcg of adrenaline, should be administered. Verbal contact and repeated monitoring of heart rate and blood pressure should be maintained for 5 min following the test dose after which, in the absence of signs of subarachnoid or intravascular injection, the main dose may be given.
Use of a test dose containing adrenaline may have further advantages in that an intravascular injection of adrenaline will be quickly recognised by an increase in heart rate, usually within about 40 sec. To detect this, the heart rate and rhythm should be monitored with an electrocardiogram (ECG).
An accidental intrathecal injection may be recognised by signs of a spinal block.
Prior to administration of the total dose, aspiration should be repeated. The main dose should be injected slowly at a rate of 25-50 mg/min, while closely observing the patient's vital functions and maintaining verbal contact. If toxic symptoms or signs occur, the injection should be stopped immediately.
Prolonged Blocks: When prolonged blocks are used, either by continuous infusion or by repeated bolus administration, the risks of reaching a toxic plasma concentration or inducing a local neural injury must be considered.
Pregnancy: It should be noted that the dose should be reduced in patients in the late stages of pregnancy.
Debilitated or Elderly Patients: Debilitated or elderly patients, including those with partial or complete heart block, advanced liver disease or severe renal dysfunction should be given a reduced dosage commensurate with their physical condition (see Precautions).
Children: Experience with bupivacaine in children <12 years is limited. The dosage in children should be calculated on a weight basis up to 2 mg/kg.