Fluothane is an inhalation anesthetic. Induction and recovery are rapid, and depth of anesthesia can be rapidly altered. Fluothane progressively depresses respiration. There may be tachypnea with reduced tidal volume and alveolar ventilation. Fluothane is not an irritant to the respiratory tract, and no increase in salivary or bronchial secretions ordinarily occurs. Pharyngeal and laryngeal reflexes are rapidly obtunded. It causes bronchodilation. Hypoxia, acidosis, or apnea may develop during deep anesthesia.

Fluothane reduces the blood pressure and frequently decreases the pulse rate. The greater the concentration of the drug, the more evident these changes become. Atropine may reverse the bradycardia. Fluothane does not cause the release of catecholamines from adrenergic stores. Fluothane also causes dilation of the vessels of the skin and skeletal muscles.

Cardiac arrhythmias may occur during Fluothane anesthesia. These include nodal rhythm, AV dissociation, ventricular extrasystoles, and asystole. Fluothane sensitizes the myocardial conduction system to the action of epinephrine and norepinephrine, and the combination may cause serious cardiac arrhythmias. Fluothane increases cerebrospinal-fluid pressure. Fluothane produces moderate muscular relaxation. Muscle relaxants are used as adjuncts in order to maintain lighter levels of anesthesia. Fluothane augments the action of nondepolarizing relaxants and ganglionic-blocking agents. Fluothane is a potent uterine relaxant.

The mechanism(s) whereby Fluothane and other substances induce general anesthesia is unknown. Fluothane is a very potent anesthetic in humans, with a minimum alveolar concentration (MAC) determined to be 0.64%. The MAC has been found to decrease with age (see MAC table in "Dosage and Administration").

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