Chirocaine

Uses

For the production of local or regional anesthesia for surgery and obstetrics, and for post-operative pain management

Chirocaine is also used to associated treatment for these conditions: Pain, Local anesthesia therapy, Lumbar epidural anesthesia therapy

How Chirocaine works

Local anesthetics such as Chirocaine block the generation and the conduction of nerve impulses, presumably by increasing the threshold for electrical excitation in the nerve, by slowing the propagation of the nerve impulse, and by reducing the rate of rise of the action potential. In general, the progression of anesthesia is related to the diameter, myelination and conduction velocity of affected nerve fibers. Specifically, the drug binds to the intracellular portion of sodium channels and blocks sodium influx into nerve cells, which prevents depolarization.

Dosage

Chirocaine dosage

Acute pain: Pain relief during labour: 15-50 mg (6-20 ml) of a 0.25% solution, to be given as a bolus dose; alternatively, dose may be given via continuous infusion at 5-12.5 mg (4-10 ml) per hr using 0.125% solution or 5-12.5 mg (8-20 ml) per hr using 0.0625% solution.

Postoperative pain: 10-25 mg (4-10 ml) per hr of a 0.25% solution, 12.5-18.75 mg (10-15 ml) per hr of a 0.125% solution or 12.5-18.75 mg (20-30 ml) per hr of a 0.0625% solution; dose may be given as an epidural infusion. Max: 150 mg/dose; 400 mg/day.

Peripheral nerve block: 2.5-150 mg or 1-2 mg/kg (0.4 ml/kg) of a 0.25 or 0.5% solution. Not to exceed 40 ml. Max: 150 mg/dose; 400 mg/day.

Surgical anaesthesia: Epidural block: 50-100 mg (10-20 ml) of a 0.5% solution or 75-150 mg (10-20 ml) of a 0.75% solution. Caesarean section: 75-150 mg (15-30 ml) of a 0.5% solution. Spinal block: 15 mg (3 ml) of a 0.5% solution. Max: 150 mg/dose; 400 mg/day.

Infiltration anaesthesia:

• Adult: Up to 150 mg (60 ml) of a 0.25% solution. For peribulbar block in ophth procedures: 37.5-112.5 mg (5-15 ml) of a 0.75% solution. Max: 150 mg/dose; 400 mg/day.
• Child: For ilioinguinal or iliohypogastric blocks in children <12 yr: 0.625-2.5 mg/kg (0.25-0.5 ml/kg) of a 0.25 or 0.5% solution.

When needed, dilutions should be made with normal saline.Not to be used in IV regional anesth (Bier's block) and paracervical block in obstetrics. Do not use 0.75% solution for epidural block in obstetrics. Hypovolaemia, complete heart block.

Side Effects

CNS effects such as restlessness, anxiety, dizziness, confusion, respiratory depression and convulsions. Neuromuscular and skeletal weakness, blurred vision, pupillary constriction, tinnitus. Hypotension, bradycardia and CV collapse which may lead to cardiac arrest. Rarely, hypersensitivity reactions.

Toxicity

LD50: 5.1mg/kg in rabbit, intravenous; 18mg/kg in rabbit, oral; 207mg/kg in rabbit, parenteral; 63mg/kg in rat, subcutaneous (Archives Internationales de Pharmacodynamie et de Therapie. Vol. 200, Pg. 359, 1972.) Chirocaine appears to cause less myocardial depression than both bupivacaine and ropivacaine, despite being in higher concentrations.

Precaution

Epilepsy, respiratory impairment, impaired cardiac conduction, bradycardia, severe shock, acute porphyria, myasthenia gravis, renal or hepatic impairment. Pregnancy, lactation. Reduce dose in elderly or debilitated patients. Resuscitative equipment should be available. Do not use solutions containing adrenaline for anesth in appendages. Do not use solutions containing preservatives for caudal or epidural block.

Interaction

Plasma levels may be reduced when used with enzyme-inducing drugs such as rifampicin. Substrates for or inhibitors of CYP3A4 and CYP1A2 may affect the plasma levels of levobupivacaine.

Food Interaction

Chirocaine Drug Interaction

Major: lidocaine / prilocaine topical, phenytoinModerate: lidocaine topicalUnknown: tropicamide ophthalmic, nimodipine, ceftriaxone

Volume of Distribution

66.91 ±18.23 L [after intravenous administration of 40 mg in healthy volunteers]

Elimination Route

The plasma concentration of levobupivacaine following therapeutic administration depends on dose and also on route of administration, because absorption from the site of administration is affected by the vascularity of the tissue. Peak levels in blood were reached approximately 30 minutes after epidural administration, and doses up to 150 mg resulted in mean C_max levels of up to 1.2 µg/mL.

Half Life

3.3 hours

Clearance

39.06 ±13.29 L/h [after intravenous administration of 40 mg in healthy volunteers]

Elimination Route

Following intravenous administration, recovery of the radiolabelled dose of levobupivacaine was essentially quantitative with a mean total of about 95% being recovered in urine and feces in 48 hours. Of this 95%, about 71% was in urine while 24% was in feces.

Pregnancy & Breastfeeding use

Pregnancy Category B. Either animal-reproduction studies have not demonstrated a foetal risk but there are no controlled studies in pregnant women or animal-reproduction studies have shown an adverse effect (other than a decrease in fertility) that was not confirmed in controlled studies in women in the 1st trimester (and there is no evidence of a risk in later trimesters).

Contraindication

Not to be used in IV regional anesth (Bier's block) and paracervical block in obstetrics. Do not use 0.75% solution for epidural block in obstetrics. Hypovolaemia, complete heart block.

Storage Condition

To be used immediately after opening. After dilution in normal saline: Chemical and physical in-use stability at 20-22°C for 7 days.

Innovators Monograph

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