(British Approved Name, US Adopted Name, rINN)
(British Approved Name Modified, rINNM)
INNs in main languages (French, Latin, and Spanish):
(BANM, US Adopted Name, rINNM)
International Nonproprietary Names (INNs) in main languages (French, Latin, and Spanish):
Pharmacopoeias. In US.
The United States Pharmacopeia 31, 2008 (Loxapine Succinate). A white to yellowish, odourless, crystalline powder. Store in airtight containers.
Adverse Effects, Treatment, and Precautions
As for Chlorpromazine.
Other adverse effects reported include nausea and vomiting, seborrhoea, dyspnoea, ptosis, headache, paraesthesia, facial flush, weight gain or loss, and polydipsia.
Abuse. There has been a report of 3 cases of loxapine succinate abuse.
Effects on carbohydrate metabolism. Reversible nonketotic hyperglycaemia, coma, and delirium developed in a patient receiving loxapine 150 mg daily in addition to lithium therapy. Symptoms improved on stopping loxapine, but subsequently recurred when the patient was given amoxapine. The causative agent may have been 7-hydroxyamoxapine, a common metabolite of both amoxapine and loxapine.
Mania. A patient, initially diagnosed as having schizophrenia, developed manic symptoms after receiving loxapine. The diagnosis was revised to schizoaffective disorder but it was suspected that loxapine had a role in the emergence of the affective symptoms. As loxapine shares common metabolites with the antidepressant amoxapine it was suggested that an antidepressant effect might have precipitated the manic symptoms.
Overdosage. An 8-year-old child was treated with activated charcoal within 30 minutes of being given 375 mg of loxapine by accident. The child became drowsy and was asleep but arousable 1 hour after ingestion. The degree of sedation appeared to peak after 3.75 hours and the child was discharged about 20 hours after ingestion.
As for Chlorpromazine.
Loxapine is readily absorbed from the gastrointestinal tract peak plasma concentrations occur within 1 to 2 hours. It is very rapidly and extensively metabolised and there is evidence for a first-pass effect. It is mainly excreted in the urine, in the form of its conjugated metabolites, with smaller amounts appearing in the faeces as unconjugated metabolites a substantial proportion of a dose is excreted in the first 24 hours. The major metabolites of loxapine are the active 7- and 8-hydroxyloxapine, which are conjugated to the glucuronide or sulfate other metabolites include hydroxyloxapine-N-oxide, loxapine-N-oxide, and hydroxydesmethyl-loxapine (hydroxyamoxapine). Loxapine is widely distributed and is thought, on the basis of animal studies, to cross the placenta and be distributed into breast milk.
Uses and Administration
Loxapine is a dibenzoxazepine with general properties similar to those of the phenothiazine, chlorpromazine. It is given orally as the succinate and by intramuscular injection as the base in the treatment of psychoses including schizophrenia. Doses are expressed in terms of the base loxapine succinate 34 mg is equivalent to about 25 mg of loxapine.
The usual oral dose is 20 to 50 mg daily initially, in 2 divided doses, increased according to response over the next 7 to 10 days to 60 to 100 mg daily or more, in 2 to 4 divided doses the maximum recommended dose is 250 mg daily. Maintenance doses are usually in the range of 20 to 60 mg daily, in divided doses. For the control of acute conditions it is given by intramuscular injection in daily doses of up to 300 mg in 2 or 3 divided doses. Reduced dosage may be required in elderly patients. Loxapine has also been given orally and by intramuscular injection as the hydrochloride.
Disturbed behaviour. For a discussion of the use and limitations of antipsychotics such as loxapine in patients with disturbed behaviour.
Schizophrenia. A brief review of loxapine found no conclusive evidence that it was particularly effective in patients with paranoid schizophrenia. A subsequent systematic review considered that the limited evidence did not indicate a clear difference in its effects from other antipsychotics.
The United States Pharmacopeia 31, 2008: Loxapine Capsules