Bupivacaine Research Paper

Pharmacokinetics
The pKa of Bupivacaine is 8.1. It possesses a great degree of lipid solubility and is highly protein bound. It is 14 times more potent than lignocaine.
Absorption and distribution
The site of injection, dose administered, addition of vasoconstrictor agent and volume of drug influences the systemic absorption of local anaesthetic. A local anaesthetic solution distributed to an area of greater vascularity leads to greater rate and degree of absorption. The final plasma concentration of a local anaesthetic is determined by the rate of tissue distribution and the rate of clearance of the drug69. Amide local anaesthetics are widely distributed in the tissues following systemic absorption.
Metabolism and clearance:
Metabolism occurs
It is also dependent on the duration of anaesthesia, individual tolerance and physical condition of the patient.
The major advantage of bupivacaine appears to be in its ability to cause differential blockade of sensory and motor fibres. This property is used when bupivacaine is administered in extradural space in obstetrics when adequate analgesia is achieved without significant motor blockade, so that the patient in labour is able to move her legs71.
0.25% bupivacaine should be used for postoperative analgesia and operation in which muscle relaxation is not required or when other means of providing muscle relaxation is used concurrently. Onset of action may be slower than with 0.5% or
0.75% produces complete motor block, most useful for epidural block in abdominal operations requiring complete muscle relaxation and retro bulbar anaesthesia.
Maximum dosage limit should be individualized in each case after evaluating the size and physical status of the patient as well as usual rate of absorption from particular site. The total dose should not cross 2 mg/kg.
Duration of action:
The average duration of surgical anaesthesia of bupivacaine varies approximately from 3 to 10 hours72. Its longest duration of action occurs when major peripheral nerve blocks such as brachial plexus blockade are performed. In these situations, average duration of effective surgical anaesthesia of 10-12 hours has been reported. When administered in the subarachnoid space, onset of spinal anaesthesia occurs within 5 minutes while the duration of surgical anaesthesia persists for 3-4 hours.
Side effects:
I. Cardiovascular system reactions:
Unintentional intravascular injection of bupivacaine during regional anaesthesia or peripheral nerve blocks causes severe cardio toxic effects including hypotension, ventricular fibrillation and atrio-ventricular