Monograph: |
Alimemazine Tartrate
A white or slightly cream, odourless or almost odourless powder. It darkens on exposure to light. Freely soluble in water and in chloroform; sparingly soluble in alcohol; very slightly soluble in ether. A 2% solution in water has a pH of 5.0 to 6.5. Protect from light.
Adverse Effects and Precautions
As for the sedating antihistamines in general.
Children.
There have been reports of adverse effects in children given alimemazine tartrate by mouth. Fatal malignant hyperthermia and severe cardiovascular depression have occurred after its use for premedication, and severe respiratory and CNS depression after use as a postoperative sedative. Doses in these 3 reports ranged from 2.4 to 4.4 mg/kg. Although unconfirmed, a possible association between phenothiazine sedatives and sudden infant death syndrome has also been suggested (see Promethazine Hydrochloride. Alimemazine tartrate is no longer licensed in the UK for short-term sedation in children and it is recommended that it should not be used in infants less than 2 years of age (but see below). The maximum recommended dose for premedication of children aged 2 to 7 years is 2 mg/kg by mouth; the BNFC suggests a maximum of 60 mg. There has been a warning that the use of alimemazine for deep sedation in diagnostic and therapeutic procedures in children is associated with prolonged drowsiness and that standards of monitoring, starvation, and postprocedural care should be similar to those with general anaesthesia.
Pregnancy.
For a discussion of the use of antihistamines in pregnancy, including studies involving phenothiazines, see.
Interactions
As for the sedating antihistamines in general.
Uses and Administration
Alimemazine, a phenothiazine derivative, is a sedating antihistamine with antiemetic activity and pronounced sedative effects. It also has some antimuscarinic actions. It is used mainly for the relief of urticaria and pruritus, and, in the UK, for pre-operative medication in children. Alimemazine may also be used in compound preparations for the symptomatic treatment of coughs.
Alimemazine tartrate is given by mouth; doses in the UK are given as the amount of alimemazine tartrate; those in the USA are expressed in terms of the equivalent amount of alimemazine. Alimemazine tartrate 25 mg is equivalent to about 20 mg of alimemazine. Even allowing for this, lower doses are used in the USA.
The adult dose of alimemazine tartrate used for the relief of urticaria and pruritus in the UK is 10 mg two or three times daily; up to 100 mg daily has been given in refractory cases. Elderly patients are given 10 mg once or twice daily and children over 2 years of age 2.5 to 5 mg three or four times daily. Despite the view that alimemazine should not be given to younger children, and although not licensed in the UK, the BNFC suggests that 250 micrograms/kg (maximum of 2.5 mg) three or four times daily by mouth may be given to those aged 6 months to 2 years for the relief of urticaria and pruritus, but only under specialist care.
In the USA the adult dose is the equivalent of alimemazine 2.5 mg four times daily. Children in the USA 3 years of age and over may be given 2.5 mg at night or three times daily.
The usual recommended dose in the UK for premedication in children aged 2 to 7 years is up to 2 mg/kg given by mouth about one to two hours before the operation. The BNFC recommends a maximum total dose of 60 mg.
Anaesthesia.
Alimemazine tartrate may be used for anaesthetic premedication in children if the oral route is preferred to the more usual parenteral route of other phenothiazine antihistamines. Adverse effects have, however, been reported in children (see under Adverse Effects and Precautions, and in the UK alimemazine tartrate is not licensed for use in infants less than 2 years of age.
Insomnia.
Antihistamines such as alimemazine tartrate have been used as alternatives to benzodiazepines for the short-term treatment of insomnia, particularly for children. However, their antimuscarinic side-effects may prove troublesome.
Regimens involving a short course of alimemazine tartrate in high dosage were tried in order to alter the sleep pattern of children with sleeping difficulties. Adverse effects have, however, been reported in children (see under Adverse Effects and Precautions. The UK product is no longer indicated for short-term sedation in children and should not be used in infants less than 2 years of age.
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