Source: Medicines & Healthcare Products Regulatory Agency (GB) Revision Year: 2018 Publisher: Focus Pharmaceuticals Limited, Capital House, 85 King William Street, London, EC4N 7BL, United Kingdom
Pharmacotherapeutic group: Psycholeptics
ATC code: N05AB06
Trifluoperazine is one of the phenothiazine class of compounds and as such has many pharmacodynamic effects which relate to its therapeutic actions and side effects. The most notable action of phenothiazines is antagonism at dopamine receptors in the CNS. It is hypothesised that this action in the limbic system and associated areas of cerebral cortex is the basis of the antipsychotic action of phenothiazines, whilst in the medullary chemoreceptor trigger zone it appears to be responsible for the antiemetic effect of these agents. In addition, dopamine antagonism in the basal ganglia appears to be involved in some of the extrapyramidal side-effects of phenothiazines, whilst blockage of the dopaminergic inhibition of prolactin release from the anterior pituitary gland is thought to lead to hyperprolactinaemia.
Other central actions of phenothiazines include sedation and inhibition of the function of the hypothalmic heat regulatory centre. Phenothiazines also lower the seizure threshold. Central actions of phenothiazines also affect the cardiovascular system, as does their antagonism of peripheral α-adrenergic receptors, which can cause hypotension.
Phenothiazines also have anti-muscarinic activity which causes certain side effects.
Trifluoperazine is one of the piperazine sub-class of phenothiazine drugs whose members have fewer sedative, antimuscarinic and hypotensive side-effects but more extrapyramidal side effects than other types of phenothiazines.
The pharmacokinetics for trifluoperazine are typical of phenothiazines such as chlorpromazine.
It is readily absorbed from the gastrointestinal tract with peak plasma levels being reached from 1.5 to 6.0 hours after ingestion. A high interindividual variation in bioavailability has been consistently reported.
In the blood, trifluoperazine is highly bound to plasma proteins. It probably penetrates the placental barrier and enters breast milk like chlorpromazine.
Several metabolites of trifluoperazine have been identified, including an N-oxide, a sulphoxide and a 7-hydroxy derivative. The N-oxide is thought to be the main metabolite and possibly active. This and the sulphoxide metabolite are thought to be extensively metabolised pre-systemically (i.e. in the gut and/or liver), whilst the 7-hydroxy derivative appears to undergo no such metabolism.
The elimination of trifluoperazine from the blood is multiphasic with an alpha phase elimination half-life of about 3.6 hours and a terminal elimination half-life of about 22 hours. Elimination occurs via bile and urine.
Not applicable.
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