Isoflurane

Indications

Isoflurane is used for: General anaesthesia

Adult Dose

Anesthesia Induction & Maintenance Use calibrated vaporizer Induction: 1.5-3% can produce surgical anesthesia in 7-10 minutes Maintenance: 1-2.5% with nitrous oxide Additional 0.5-1% may be needed if given with oxygen alone

Child Dose

Safety & efficacy not established

Renal Dose

Administration

Contra Indications

Known or suspected susceptibility to malignant hyperthermia. Porphyria.

Precautions

Perioperative hyperkalaemia; raised intracranial pressure. May impair ability to drive or operate machinery. Pregnancy and lactation. Do not allow carbon dioxide absorbents in anaesthetic apparatus to dry out when delivering isoflurane to minimise the risk of developing elevated carboxyhaemoglobin levels. Lactation: use caution

Pregnancy-Lactation

Pregnancy There are no adequate and well-controlled studies in pregnant women; in animal reproduction studies, embryofetal toxicity was noted in pregnant mice exposed to 0.075% (increased post implantation losses) and 0.3% isoflurane (increased post implantation losses and decreased live- birth index) during organogenesis Lactation Use caution

Interactions

Enhances effects of neuromuscular blockers. May sensitise the myocardium to adrenaline and other sympathomimetics. Enhances hypotensive effects of ACE inhibitors, TCAs, MAOIs, antihypertensives, antipsychotics or beta-blockers. May have synergistic effects with CNS depressants.

Adverse Effects

Side effects of Isoflurane : 1-10% Nausea, Vomiting, Shivering <1% Dose-dependent hypotension, Arrhythmias, Malignant hyperthermia (rare), Elevations in white blood count, May decrease creatinine and increase BUN, Ileus, severe (fatal), Hepatic dysfunction (postoperative period) (rare), Respiratory depression may occur (rare)

Mechanism of Action

Isoflurane, a volatile halogenated anaesthetic, causes a reversible loss of consciousness and pain sensations, suppression of voluntary motor activity, modification of autonomic reflexes, and depression of the respiratory and the CV system.