Antiemetic;Dopamine antagonist
Used as an Antiemetic, Antipsychotic
Chlorpromazine hydrochloride is used in the treatment of schizophrenia; anti-emetic; as an antipsychotic in pills, injections, and suppositories; to relieve nausea and
vomiting associated with malignant diseases. In veterinary medicine, it is used as an anti-emetic, tranquilizer and sedative. It has slight
antihistaminic and anti adrenaline actions. It is a peripheral vasodilator and adepressant that blocks dopamine receptors in the central
nervous system.
ChEBI: The hydrochloride salt of chlorpromazine.
To a boiling suspension of 11.6 g of chlorophenothiazine (consisting of a
mixture of two isomers melting at 196° to 198°C and 116° to 117°C,
respectively, the latter in minor proportion) and 2.4 g of sodium amide (80%)
in 60 cc of xylene, there are added over a period of one hour 7.5 g of 3-
dimethylamino-1-chloropropane in solution in its own weight of xylene. At the
end of the addition, heating is continued for one hour under reflux. After
cooling, the contents are taken up in acidified water and the xylene separated.
The aqueous layer is made strongly alkaline by means of sodium hydroxide in
order to liberate the base and this is extracted with ether. On distillation of
the ethereal extract there is obtained 10-(3'-dimethylamino-propyl)-
chlorophenothiazine which distills at 200° to 205°C under a pressure of 0.8
mm Hg. Its hydrochloride, recrystallized from chlorobenzene, melts at 177° to
178°C. The chlorophenothiazine may be prepared by reacting mchlorodiphenylamine with sulfur in the presence of an iodine catalyst.
Thorazine (GlaxoSmithKline).
Chlorpromazinehydrochloride, 2-chloro-10-[3-(dimethylamino)propyl]phenothiazine monohydrochloride (Thorazine), was the first phenothiazinecompound introduced into therapy. It is still usefulas an antipsychotic. Other uses are in nausea, vomiting, andhiccough. Oral doses of chlorpromazine and thioridazinehave systemic availability of 25% to 35% because of significantfirst-pass metabolism. Chlorpromazine and other phenothiazinesare metabolized extensively by CYP2D6. In contrast, bioavailability of chlorpromazine may beincreased up to 10-fold with injections, but the clinical doseusually is decreased by only threefold to fourfold.Chlorpromazine may weakly induce its own hepatic metabolism,because its concentration in blood is lower after severalweeks of treatment at the same dosage. Alterations of GImotility also may contribute. The drug has significant sedativeand hypotensive properties, possibly reflecting centralhistaminergic and peripheral α1-noradrenergic blockingactivity, respectively. Effects of peripheral anticholinergic activityare common. As with the other phenothiazines, the effectsof other CNS-depressant drugs, such as sedatives andanesthetics, can be potentiated.
White or creamy-white odorless crystalline powder with very bitter taste. pH (5% aqueous solution) 4.0-5.5. pH (10% aqueous solution) 4-5.
Decomposes on exposure to air and light. becoming yellow, pink and, finally, violet. Water soluble.
Chlorpromazine hydrochloride is incompatible in aqueous solution with sodium salts of barbiturates and other alkaline solutions. Solutions may be stabilized by addition of antioxidants and storing under nitrogen.
Flash point data for Chlorpromazine hydrochloride are not available; however, Chlorpromazine hydrochloride is probably combustible.
dopamine receptors are a class of g protein-coupled receptors that are prominent in the central nervous system. dopamine receptors are implicated in many neurological processes. thus, dopamine receptors are common neurologic drug targets. antipsychotics are often dopamine receptor antagonists while typically psychostimulants are indirect agonists of dopamine receptors. chlorpromazine is a dopamine antagonist.
Chlorpromazine demonstrates cytotoxic and antiproliferative activity against leukemic cells, but does not affect the viability of normal lymphocytes.
Poison by ingestion,
intraperitoneal, intravenous, and
subcutaneous routes. An experimentalteratogen. Experimental reproductive
effects. An anti-emetic and antipsychotic
drug. Human systemic effects: anorexia
(human), excitement, gastrointestinal
changes, irritability, pulse rate increase,
respiratory stimulation, rigidity, somnolence,
sweating. Mutation data reported. When
heated to decomposition it emits very toxic
fumes of Cl-, NOx, and SOx.
Veterinary Drugs and Treatments
The clinical use of chlorpromazine as a neuroleptic agent has diminished,
but the drug is still used for its antiemetic effects in small
animals and occasionally as a preoperative medication
and tranquilizer.
As an antiemetic, chlorpromazine will inhibit apomorphineinduced
emesis in the dog but not the cat. It will also inhibit the
emetic effects of morphine in the dog. It does not inhibit emesis
caused by copper sulfate, or digitalis glycosides.
Once the principle phenothiazine used in veterinary medicine,
chlorpromazine has been largely supplanted by acepromazine. It
has similar pharmacologic activities as acepromazine, but is less potent
and has a longer duration of action. For further information,
refer to the acepromazine
monograph.
the antipsychotic activity of chlorpromazine has been associated with its ability to act as a dopamine-receptor antagonist. the manner in which chlorpromazine, with its phenothiazine ring structure, interacted with a receptor for dopamine. furthermore, chlorpromazine inhibited the binding of [3h]spiperone, and the inhibition curve was consistent with a single class of binding sites [1].
daily administration of chlorpromazine to rats for 21 days induced catalepsy, tolerance to catalepsy and locomotor sensitization following pcp challenge. results suggest that daily chlorpromazine treatment induced da/nmda-receptor sensitization to total locomotor activity following pcp challenge [2].
Potentially hazardous interactions with other drugs
Anaesthetics: enhanced hypotensive effect.
Analgesics: increased risk of convulsions with
tramadol; enhanced hypotensive and sedative
effects with opioids; increased risk of ventricular
arrhythmias with methadone.
Anti-arrhythmics: increased risk of ventricular
arrhythmias with anti-arrhythmics that prolong
the QT interval and disopyramide; avoid with
amiodarone and dronedarone.
Antibacterials: increased risk of ventricular
arrhythmias with delamanid, moxifloxacin and
telithromycin - avoid with moxifloxacin.
Antidepressants: increased level of tricyclics,
possibly increased risk of ventricular arrhythmias
and antimuscarinic side effects; increased risk
of ventricular arrhythmias with citalopram and
escitalopram - avoid; increased risk of convulsions
with vortioxetine.
Anticonvulsants: antagonises anticonvulsant effect;
concentration of fosphenytoin and phenytoin
possibly increased or decreased; concentration of
both drugs reduced with phenobarbital.
Antimalarials: avoid with artemether/lumefantrine
and piperaquine with artenimol.
Antipsychotics: increased risk of ventricular
arrhythmias with droperidol and pimozide - avoid;
concentration of haloperidol possibly increased;
possible increased risk of ventricular arrhythmias
with risperidone.
Antivirals: concentration possibly increased with
ritonavir; increased risk of ventricular arrhythmias
with saquinavir - avoid.
Anxiolytics and hypnotics: increased sedative effects.
Atomoxetine: increased risk of ventricular
arrhythmias.Beta-blockers: enhanced hypotensive effect;
concentration of both drugs may increase
with propranolol; increased risk of ventricular
arrhythmias with sotalol.
Cytotoxics: increased risk of ventricular arrhythmias
with vandetanib - avoid; increased risk of ventricular
arrhythmias with arsenic trioxide.
Diuretics: enhanced hypotensive effect.
Lithium: increased risk of extrapyramidal side effects
and possibly neurotoxicity.
Pentamidine: increased risk of ventricular
arrhythmias.
Ulcer-healing drugs: effects enhanced by cimetidine.
Chlorpromazine is subject to considerable first-pass
metabolism in the gut wall and is also extensively
metabolised in the liver. Paths of metabolism of
chlorpromazine include hydroxylation and conjugation
with glucuronic acid, N-oxidation, oxidation of a sulfur
atom, and dealkylation.
Chlorpromazine is excreted in the urine and bile in the
form of both active and inactive metabolites; there is some
evidence of enterohepatic recycling.
[1] harrold mw, chang ya, wallace ra, farooqui t, wallace lj, uretsky n, miller dd. charged analogues of chlorpromazine as dopamine antagonists. j med chem. 1987 sep;30(9):1631-5.
[2] nsimba se. effects of daily chlorpromazine administration on behavioural and physiological parameters in the rat. indian j physiol pharmacol. 2009 jul-sep;53(3):209-18.
