Overview
11 DESCRIPTION Isoflurane USP, a nonflammable liquid administered by vaporizing, is a general inhalation anesthetic drug. It is 1-chloro-2,2,2-trifluoroethyl difluoromethyl ether, and its structural formula is: iso structure Some physical constants are: Molecular weight 184.5 Boiling point at 760 mm Hg 48.5°C Refractive index n 20/D 1.2990-1.3005 Specific gravity 25°/25°C 1.
Mechanism of Action
12 CLINICAL PHARMACOLOGY 12.2 Pharmacodynamics Induction of and recovery from isoflurane anesthesia are rapid. Isoflurane has a mild pungency which limits the rate of induction, although excessive salivation or tracheobronchial secretions do not appear to be stimulated. Pharyngeal and laryngeal reflexes are readily obtunded. The level of anesthesia may be changed rapidly with isoflurane. Isoflurane is a profound respiratory depressant. As anesthetic dose is increased, tidal volume decreases and respiratory rate is unchanged. This depression is partially reversed by surgical stimulation, even at deeper levels of anesthesia. Isoflurane evokes a sigh response reminiscent of that seen with diethyl ether and enflurane, although the frequency is less than with enflurane.
Indications
- 1 INDICATIONS AND USAGE Isoflurane USP may be used for induction and maintenance of general anesthesia. Adequate data have not been developed to establish its application in obstetrical anesthesia. Isoflurane USP, a general anesthetic, is an inhalation agent indicated for induction and maintenance of general anesthesia. ( 1 )
Common Doses
- Refer to label
Dosage
2 DOSAGE AND ADMINISTRATION • Isoflurane USP should be administered only by persons trained in the administration of general anesthesia. Isoflurane USP should only be delivered using a vaporizer specifically designed and designated for use with isoflurane. ( 2 ) • The administration of general anesthesia must be individualized and titrated based on the patient’s age and clinical status. ( 2 ) 2.1 Important Dosage and Administration Information Isoflurane should be administered only by persons trained in the administration of general anesthesia.
Contraindications
- 4 CONTRAINDICATIONS Isoflurane USP is contraindicated in patients: • in whom general anesthesia is contraindicated. • with known sensitivity to Isoflurane USP or to other halogenated agents [see Warnings and Precautions ( 5.3 )]. • with known or suspected genetic susceptibility to malignant hyperthermia [see Warnings and Precautions ( 5.1 ), Clinical Pharmacology ( 12.5 )]. • with a history of confirmed hepatitis due to a halogenated inhalational anesthetic or a history of unexplained moderate to severe hepatic dysfunction (e.g.
Side Effects
- 6 ADVERSE REACTIONS Most common adverse reactions (incidence > 5%) are agitation, cough, breath holding, nausea, chills/shivering, vomiting, laryngospasm, delirium. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Piramal Critical Care, Inc. at 1-888-822-8431 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience The following adverse reactions were identified from controlled clinical trials of adult and pediatric subjects exposed to Isoflurane USP.
Interactions
- 7 DRUG INTERACTIONS • Concomitant use of N 2 O and/or opioids reduces the MAC of Isoflurane USP. Adjust dose accordingly. ( 7.1 , 7.2 ) • Isoflurane USP decreases the doses of neuromuscular blocking agents required. Adjust dose accordingly. ( 7.3 ) 7.1 Opioids Opioids decrease the Minimum Alveolar Concentration (MAC) of isoflurane. Opioids such as fentanyl and its analogues, when combined with isoflurane, may lead to a synergistic fall in blood pressure and respiratory rate. 7.2 Nitrous Oxide Nitrous oxide decreases the MAC of isoflurane [see Dosage and Administration (2.1) ]. 7.