Isoflurane USP Liquid for Inhalation - Product Details
PRESENTATION
A clear, colorless, volatile, non-flammable liquid for general inhalation anesthesia.
ACTIONS
ISOFLURANE is used to induces and maintain general anesthesia by depression of the central nervous system and resultant loss of consciousness.
PHARMACOKINETICSISOFLURANE shows very low solubility in blood and body tissues, much lower than for enflurane and halothane, thus its partial pressure (concentration) in alveolar gas or arterial blood rises to 50% of the inspired partial pressure (concentration) within 4-8 minutes of the start of its inhalation, and to 60% within 15 minutes. This rate of rise is slightly faster than that obtained with enflurane and considerably faster (40%) than the more soluble halothane. Age significantly affects blood-gas partition coefficients for all anaesthetics; the lower blood-gas partition coefficients in children explain in part the more rapid increase in alveolar anaesthetic partial pressures in this group. Throughout maintenance of anesthesia, a high proportion of the ISOFLURANE inspired is eliminated by the lungs. When administration is stopped and inspired concentration becomes zero, the bulk of the remaining ISOFLURANE is eliminated unchanged from the lungs. In keeping with its low solubility, recovery from ISOFLURANE anesthesia in man is rapid. Biotransformation of ISOFLURANE is significantly less than that of enflurane or halothane. Humans and animals biotransform a small fraction of ISOFLURANE administered. In man about 0.2% administered is evident as recoverable metabolites (fluoride and organic fluorine), with approximately 50% of these excreted in the urine, the principal metabolite being trifluoracetic acid. Enzyme induction associated with pre-existing drug therapy would not appear to be an important factor in the metabolism of ISOFLURANE in man, mainly because the overall metabolism of ISOFLURANE is so low.
INDICATIONSAs ISOFLURANE has a mild pungency, inhalation should usually be preceded by the choice of a short acting barbiturate, or other intravenous induction agent, to prevent coughing. Salivation and coughing may be troublesome in small children induced with Isoflurane. Alternatively, ISOFLURANE with oxygen or an oxygen/nitrous oxide mixture may be administered. It is recommended that induction with ISOFLURANE be initiated at a concentration of 0.5%. Concentrations of 1.5-3.0% usually produce surgical anesthesia in 7-10 minutes.
DOSAGE AND ADMINISTRATIONThe use of ISOFLURANE-specific vaporizers facilitates accurate control of the administered concentration of anesthetic.
PRE-MEDICATIONThe ventilator depressant effect of ISOFLURANE should be taken into account. As ISOFLURANE causes increased heart rate and only weak stimulation of secretions, the use of anticholinergic drugs is a mailer of choice.
INDUCTIONAs ISOFLURANE has a mild pungency, inhalation should usually be preceded by the choice of a short acting barbiturate, or other intravenous induction agent, to prevent coughing. Salivation and coughing may be troublesome in small children induced with Isoflurane. Alternatively, ISOFLURANE with oxygen or an oxygen/nitrous oxide mixture may be administered. It is recommended that induction with ISOFLURANE be initiated at a concentration of 0.5%. Concentrations of 1.5-3.0% usually produce surgical anesthesia in 7-10 minutes.
MAINTENANCEAdequate anesthesia for surgery may be sustained with an inspired ISOFLURANE concentration of 1.0% - 2.5% in an oxygen/ 70% nitrous oxide mixture. Additional inspired ISOFLURANE (0.5% -1 %) will be required with lower nitrous oxide levels, or when ISOFLURANE is given with oxygen alone or air/oxygen mixtures. Blood pressure decreases during maintenance anesthesia in relation to the depth of anesthesia. That is, blood pressure is inversely related to the ISOFLURANE concentration. Provided there are no other complicating factors this is probably due to peripheral vasodilation.
Cardiac rhythm remains stable. Excessive falls in blood pressure may be due to the depth of anesthesia and in such circumstances can be corrected by reducing the inspired ISOFLURANE concentration. Induced hypotension can be achieved by artificially ventilating patients with ISOFLURANE 2.5-4.0%. Pre-treatment with clonidine significantly decreases the ISOFLURANE requirement for maintaining induced hypotension.
The concentration of ISOFLURANE can be reduced to 0.5% at the start of dosing the operation wound, and then to 0% at the end of surgery, provided that the anaesthesiologlist is satisfied that the effect of any neuromuscuiar blocking drugs has been reversed and the patient is no longer paralysed. After discontinuation of all anaesthetics, the airways of the patient should be ventilated several times with oxygen 100% until complete recovery.
CONTRADICTIONSKnown sensitivity to ISOFLURANE or to other halogenated agents, especially patients with known or suspected susceptibility to malignant hyperthermia.
WARNINGS & PRECAUTIONSThe respiratory depressant effect of ISOFLURANE is accentuated by narcotic premedication.
ISOFLURANE causes an Increase in cerebral blood flow at deeper levels of anesthesia (1.5%) thereby increasing cerebral spinal fluid pressure. This can be prevented or reversed by hyperventilating the patient before or during anesthesia.
ISOFLURANE is a powerful systemic and coronary arterial dilator. The effect on systemic arterial pressure is easily controlled in the normal healthy patient and has been used specifically as a means of Indudng hypotension. However, the phenomenon of 'coronary steal' means that ISOFLURANE should be used with caution in patients with coronary artery disease. In particular, patients with subendocardial ischaemia might be anticipated to be more susceptible. Salivation and trachea-bronchial secretions may be stimulated in children but pharyngeal and laryngeal reflexes are quickly diminished.
ISOFLURANE should be used with extreme caution in patients receiving nephrotoxic drugs concomitantly.
Adverse reactions encountered are hypotension, respiratory depression and arrhythmias.
INTERACTIONSISOFLURANE is compatible with all commonly used muscle relaxants, the effects of which may be markedly potentiated by ISOFLURANE.
ADRENALINEAdministration of adrenaline cause arrhythmias during ISOFLURANE anaesthesia.
NARCOTIC ANALGESICSThe anaesthetic effect of ISOFLURANE can be potentiated by narcotic analgesics.
OVERDOSAGEOverdosing with ISOFLURANE will result in marked depression of breathing, and a marked decrease in blood pressure, the latter being predominantly due to a peripheral vasodilatation rather than direct myocardial depression. If it appears an overdose has been administered, stop drug inspiration immediately, establish a clear airway and initiate controlled ventilation with pure oxygen.
PACKAGE QUANTITIESBottles of 100 or 250 mL
