Overview
DESCRIPTION Loxapine, a dibenzoxazepine compound, represents a subclass of tricyclic antipsychotic agents, chemically distinct from the thioxanthenes, butyrophenones, and phenothiazines. Chemically, it is 2-Chloro-11-(4-methyl-1-piperazinyl)dibenz[ b,f ][1,4]oxazepine. It is present as the succinate salt. Each capsule for oral administration, contains loxapine succinate, USP 6.8, 13.6, 34.0 or 68.
Mechanism of Action
CLINICAL PHARMACOLOGY Pharmacodynamics Pharmacologically, loxapine is an antipsychotic for which the exact mode of action has not been established. However, changes in the level of excitability of subcortical inhibitory areas have been observed in several animal species in association with such manifestations of tranquilization as calming effects and suppression of aggressive behavior. In normal human volunteers, signs of sedation were seen within 20 to 30 minutes after administration, were most pronounced within one and one-half to three hours, and lasted through 12 hours. Similar timing of primary pharmacologic effects was seen in animals. Absorption, Distribution, Metabolism, and Excretion Absorption of loxapine following oral or parenteral administration is virtually complete.
Indications
- INDICATIONS AND USAGE Loxapine Capsules, USP are indicated for the treatment of schizophrenia. The efficacy of loxapine in schizophrenia was established in clinical studies which enrolled newly hospitalized and chronically hospitalized acutely ill schizophrenic patients as subjects.
Common Doses
- 10 mg
- 50 mg
- 60 mg
- 100 mg
Dosage
DOSAGE AND ADMINISTRATION Loxapine Capsules, USP are administered, usually in divided doses, two to four times a day. Daily dosage (in terms of base equivalents) should be adjusted to the individual patient's needs as assessed by the severity of symptoms and previous history of response to antipsychotic drugs. Oral Administration Initial dosage of 10 mg twice daily is recommended, although in severely disturbed patients initial dosage up to a total of 50 mg daily may be desirable.
Black Box Warning
WARNING Increased Mortality in Elderly Patients with Dementia-Related Psychosis Elderly patients with dementia-related psychosis treated with antipsychotic drugs are at an increased risk of death. Analyses of seventeen placebo-controlled trials (modal duration of 10 weeks), largely in patients taking atypical antipsychotic drugs, revealed a risk of death in drug-treated patients of between 1.6 to 1.7 times the risk of death in placebo-treated patients. Over the course of a typical 10-week controlled trial, the rate of death in drug-treated patients was about 4.
Contraindications
- CONTRAINDICATIONS Loxapine is contraindicated in comatose or severe drug-induced depressed states (alcohol, barbiturates, narcotics, etc.). Loxapine is contraindicated in individuals with known hypersensitivity to dibenzoxazepines.
Side Effects
- ADVERSE REACTIONS CNS Effects: Manifestations of adverse effects on the central nervous system, other than extrapyramidal effects, have been seen infrequently. Drowsiness, usually mild, may occur at the beginning of therapy or when dosage is increased. It usually subsides with continued loxapine therapy. The incidence of sedation has been less than that of certain aliphatic phenothiazines and slightly more than the piperazine phenothiazines.
Interactions
- Drug Interactions There have been rare reports of significant respiratory depression, stupor and/or hypotension with the concomitant use of loxapine and lorazepam. The risk of using loxapine in combination with CNS-active drugs has not been systematically evaluated. Therefore, caution is advised if the concomitant administration of loxapine and CNS-active drugs is required.