Monograph: |
Moracizine Hydrochloride
A white to off-white crystalline powder. Soluble in water and
in alcohol. Store in airtight containers.
Adverse Effects
The most common adverse effects associated with
moracizine therapy affect the central nervous sys-
tem and the gastro-intestinal tract and include dizzi-
ness, headache, fatigue, nausea, and abdominal
pain. Other adverse effects include dyspnoea, dry
mouth, blurred vision, impotence, and urinary-tract
disorders. There have been occasional reports of fe-
ver. thrombocytopenia, hepatic dysfunction, hypo-
thermia, and skin rash.
Like other antiarrhythmics moracizine can provoke
or worsen arrhythmias. This may range from an in-
crease in the frequency of premature ventricular
contractions to induction or worsening of ventricu-
lar tachycardia.
An increased mortality rate occurred when mora-
cizine was tested in the control of asymptomatic
ventricular arrhythmias in post-infarction patients
(see Cardiac Arrhythmias under Uses and Adminis-
tration, below).
Fever with elevated creatine phosphokinase and hepatic
transaminase concentrations was associated with moracizine
administration in 2 patients.' The fever abated within 48
hours of withdrawing moracizine and recurred within 24
hours of rechallenge in both patients. Results suggested a
similarity to the neuroleptic malignant syndrome which has
been attributed to other phenothiazine derivatives.
1. Milira DS. el at. Ethmozine toxicity: fever of unknown origin.
J Clin Pharmacol 1986: 26: 153-5.
Precautions
Pharmacokinetics
Moracizine is readily and almost completely ab-
sorbed from the gastro-intestinal tract. It undergoes
significant first-pass hepatic metabolism so that the
bioavailability following oral administration is
about 38%. Moracizine is extensively metabolised
and some of the numerous metabolites may be ac-
tive. It induces its own metabolism; the plasma elim-
ination half-life is about 2 hours following multiple
doses. Although plasma concentrations are reduced
with multiple dosing, clinical response is not affect-
ed. It is about 95% bound to plasma proteins. Mora-
cizine is distributed into breast milk. Approximately
56% of a dose is excreted in the faeces and approx-
imately 39% in the urine.
Uses and Administration
Moracizine is a phenothiazine compound with class
I antiarrhythmic activity but which does not
readily fall into the subclasses a, b, ore. It is used as
the hydrochloride in the treatment of serious symp-
tomatic ventricular airhythmias. Moracizine hy-
drochloride is given in a usual dose of 600 to 900 mg
daily by mouth in 2 or 3 divided doses. Doses, which
should be given initially in hospital, should be ad-
justed at intervals of not less than 3 days. If rapid
control of life-threatening arrhythmias is essential a
suggested initial dose is 400 to 500 mg followed by
200 mg every 8 hours.
Patients with hepatic or renal impairment should be
started on a dosage of 600 mg or less daily and mon-
itored closely.
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