Monograph: |
Promazine Hydrochloride
A white or slightly yellow, almost odourless, slightly hygro-
scopic, crystalline powder. It oxidises upon prolonged expo-
sure to air and acquires a pink or blue colour.
Very soluble or soluble I in 3 of water; very soluble in alcohol
and in dichloromethane: freely soluble in chloroform. A 5%
solution in water has a pH of 4.2 to 5.2. Store in airtight con-
tainers. Protect from light.
Incompatibility has been reported between promazine hy-
drochloride and several other compounds: these include ami-
nophylline. some barbiturates, benzylpenicillin potassium.
chloramphenicol sodium succinate, chlortetracycline, chloro-
thiazide sodium, dimenhydrinate. heparin, hydrocortisone so-
dium succinate. nafcillin sodium, phenytoin sodium,
prednisolone sodium phosphate, and sodium bicarbonate.
The UK manufacturers of promazine hydrochloride injection
recommend that it should not be mixed with other injections
with the exception of pethidine hydrochloride injection.
Absorption. A study of drug loss from intravenous delivery
systems. There was an 11% loss of promazine hydrochloride
from solution when infused for 7 hours via a plastic infusion
set, and a 59% loss after infusion for one hour from a glass
syringe through silastic tubing. Loss was negligible after in-
fusion for one hour from a system comprising a glass syringe
with polyethylene tubing.
Stability. A study of the stability of promazine diluted to a
0.1 % infusion in sodium chloride solution (0.9%) or glucose
(5%) found that solutions in glucose (5%) remained stable for
up to 6 days at 4Β°, and at room temperature, provided they
were stored in the dark. However with saline as the diluent
deterioration of the promazine was observed 24 hours after
preparation, even when stored in the dark. and after 8 hours
when exposed to light. Temperature had no effect on degrada-
tion rate.
Adverse Effects, Treatment, and Precautions
As for Chlorpromazine.
Pregnancy and the neonates. An increased incidence of
neonatal jaundice coincided with the increased use of pro-
mazine. A decrease in the incidence of jaundice was noted 3
months after the total withdrawal of the drug from the hospi-
tal although restriction of its use during labour had no impact.
Interactions
As for Chlorpromazine.
Pharmacokinetics
For an account of the pharmacokinetics of a pheno-
thiazine, see Chlorpromazine.
Uses and Administration
Promazine is a phenothiazine with general proper-
ties similar to those of chlorpromazine . It
has relatively weak antipsychotic activity and is not
generally used for the management of psychoses. Its
main indications are for the short-term management
of agitated or disturbed behaviour , allevia-
tion of nausea and vomiting particularly in
labour or post-operatively, and relief of intractable
hiccup . Promazine is given by mouth or in-
tramuscularly as the hydrochloride. It is also given
as the embonate by mouth, in doses equivalent to
those of the hydrochloride. Promazine hydrochlo-
ride has also been given by slow intravenous injec-
tion. in concentrations not exceeding 25 mg per mL.
For the treatment of agitated behaviour, promazine
is given in doses of 100 to 200 mg of the hydrochlo-
ride four times daily by mouth or 50 mg by intra-
muscular injection repeated if necessary after 6 to 8
hours. It has also been given by slow intravenous in-
jection for severely agitated hospitalised patients in
doses similar to those given by the intramuscular
route. A dose of 50 mg by intramuscular injection
has been given for the control of nausea and vomit-
ing; it has also been given by mouth for this indica-
tion. For intractable hiccup 50 mg is given by
intramuscular injection repeated if necessary with
doses up to 100 mg every 4 hours.
Promazine should be given in reduced dosage to eld-
erly or debilitated subjects; 25 mg by mouth of the
hydrochloride initially, increasing, if necessary, to
50 mg four times daily has been suggested for the
control of agitation and restlessness: for intramuscu-
lar injection a dose of 25 mg may be sufficient.
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