Cyclizine is an
antihistamineAn H
1 antagonist is a histamine antagonist of the H
1 receptor that serves to reduce or eliminate effects mediated by histamine, an endogenous chemical mediator released during allergic reactions...
drug used to treat
nauseaNausea is the sensation of unease and discomfort in the stomach with an urge to vomit.-Causes:...
,
vomitingVomiting is the forceful expulsion of the contents of one's stomach through the mouth and sometimes the nose. Undesired vomiting may result from many causes, ranging from gastritis or poisoning to brain tumors, or elevated intracranial pressure...
and
dizzinessDizziness refers to an impairment in spatial perception and stability. It is considered imprecise. It can be used to mean vertigo, presyncope, disequilibrium, or for a non-specific feeling such as giddiness or foolishness....
associated with
motion sicknessMotion sickness or kinetosis, also known as Travel Sickness, is a condition in which a disagreement exists between visually perceived movement and the vestibular system's sense of movement...
,
vertigoVertigo is a specific type of dizziness, a major symptom of a balance disorder. It is the sensation of spinning or swaying while the body is actually stationary with respect to the surroundings.The effects of vertigo may be slight...
and post-operative following administration of
general anaesthesiaIn modern medical practice, general anaesthesia is a state of total unconsciousness resulting from general anaesthetic drugs. A variety of drugs are given to the patient that have different effects with the overall aim of ensuring unconsciousness, amnesia and analgesia...
and
opioidAn opioid is a chemical that works by binding to opioid receptors, which are found principally in the central nervous system and the gastrointestinal tract...
s. It's also considered the gold standard of opiate/opioid-enhancing anti-histamine boosters.
Cyclizine is a
piperazinePiperazine is an organic compound that consists of a six-membered ring containing two opposing nitrogen atoms. Piperazine exists as small alkaline deliquescent crystals with a saline taste....
derivative with histamine H
1-receptor antagonist (
antihistamineAn H
1 antagonist is a histamine antagonist of the H
1 receptor that serves to reduce or eliminate effects mediated by histamine, an endogenous chemical mediator released during allergic reactions...
) activity. The precise mechanism of action in inhibiting the symptoms of motion sickness is not well understood.
Cyclizine is an
antihistamineAn H
1 antagonist is a histamine antagonist of the H
1 receptor that serves to reduce or eliminate effects mediated by histamine, an endogenous chemical mediator released during allergic reactions...
drug used to treat
nauseaNausea is the sensation of unease and discomfort in the stomach with an urge to vomit.-Causes:...
,
vomitingVomiting is the forceful expulsion of the contents of one's stomach through the mouth and sometimes the nose. Undesired vomiting may result from many causes, ranging from gastritis or poisoning to brain tumors, or elevated intracranial pressure...
and
dizzinessDizziness refers to an impairment in spatial perception and stability. It is considered imprecise. It can be used to mean vertigo, presyncope, disequilibrium, or for a non-specific feeling such as giddiness or foolishness....
associated with
motion sicknessMotion sickness or kinetosis, also known as Travel Sickness, is a condition in which a disagreement exists between visually perceived movement and the vestibular system's sense of movement...
,
vertigoVertigo is a specific type of dizziness, a major symptom of a balance disorder. It is the sensation of spinning or swaying while the body is actually stationary with respect to the surroundings.The effects of vertigo may be slight...
and post-operative following administration of
general anaesthesiaIn modern medical practice, general anaesthesia is a state of total unconsciousness resulting from general anaesthetic drugs. A variety of drugs are given to the patient that have different effects with the overall aim of ensuring unconsciousness, amnesia and analgesia...
and
opioidAn opioid is a chemical that works by binding to opioid receptors, which are found principally in the central nervous system and the gastrointestinal tract...
s. It's also considered the gold standard of opiate/opioid-enhancing anti-histamine boosters.
Pharmacology
Cyclizine is a
piperazinePiperazine is an organic compound that consists of a six-membered ring containing two opposing nitrogen atoms. Piperazine exists as small alkaline deliquescent crystals with a saline taste....
derivative with histamine H
1-receptor antagonist (
antihistamineAn H
1 antagonist is a histamine antagonist of the H
1 receptor that serves to reduce or eliminate effects mediated by histamine, an endogenous chemical mediator released during allergic reactions...
) activity. The precise mechanism of action in inhibiting the symptoms of motion sickness is not well understood. It may have effects directly on the labyrinthine apparatus and on the
chemoreceptor trigger zoneThe chemoreceptor trigger zone is an area of the medulla which receives inputs from blood-borne drugs or hormones, and communicates with the vomiting center, to initiate vomiting. The CTZ is close to the area postrema on the floor of the fourth ventricle and is outside of the blood-brain barrier...
. Cyclizine exerts a central
anticholinergicAn anticholinergic agent is a substance that blocks the neurotransmitter acetylcholine in the central and the peripheral nervous system. An example of an anticholinergic is dicyclomine....
(antimuscarinic) action.
Contraindications
Its antimuscarinic action warrants caution in patients with
prostatic hypertrophyBenign prostatic hyperplasia also known as benign prostatic hypertrophy , benign enlargement of the prostate , and adenofibromyomatous hyperplasia, refers to the increase in size of the prostate in middle-age and elderly men...
, urinary retention,
glaucomaGlaucoma is a group of diseases that affect the optic nerve and involves a loss of retinal ganglion cells in a characteristic pattern. It is a type of optic neuropathy. Raised intraocular pressure is a significant risk factor for developing glaucoma...
. Liver disease exacerbates its sedative effects.
It cannot be combined with
diclofenacDiclofenac is a non-steroidal anti-inflammatory drug taken to reduce inflammation and as an analgesic reducing pain in conditions such as arthritis or acute injury. It can also be used to reduce menstrual pain, dysmenorrhea...
, for example in the same syringe or bag of fluids, as a crystallisation reaction occurs.
It's main off-label use is as an opioid/opiate potentiator, commonly preferred highly to other anti-histamines(most commonly used as opioid boosters:
tripelennamineTripelennamine is psychoactive drug and member of the pyridine and ethylenediamine chemical classes that is used as an antipruritic and first-generation antihistamine...
,
hydroxyzineHydroxyzine is a first-generation antihistamine of the piperazine class that is an H
1 receptor antagonist. It was synthesized in the early 1950s and the medicinal formulation of this drug was announced in the 4 August 1956 issue of Chemistry Week...
,
meclizineMeclizine is an antihistamine considered to be an antiemetic. It is sold under the brand names of Bonine, Bonamine, Antivert, Postafen, and Dramamine , and is most commonly used to inhibit nausea and vomiting. Emesafene is a combination of meclizine and pyridoxine...
,
doxylamineDoxylamine succinate is one of the many sedating antihistamines used by itself as a short-term sedative, in combination with other drugs as a night-time cold and allergy relief drug, in combination with the analgesics paracetamol and codeine as an analgesic / calmative preparation, and is...
,
diphenhydramineDiphenhydramine hydrochloride is a chemical mainly used as an antihistamine, antiemetic, sedative, and hypnotic. It is produced and marketed under the trade name Benadryl by McNeil-PPC in the U.S. and Canada, and Dimedrol in other countries...
, etc.). The drug Diconal is the opioid Dipipanone and Cyclizine combined for IV use(discontinued in the U.S. for it's high abuse potential.) Dipipanone's closest relative is Methadone.
Those using Methadone recreationally combine cyclizine with their methadone dose, a combination that is known to produce strong psychoactive effects. It is also sold in combination with another opioid
dipipanoneDipipanone is an opioid analgesic. Its hydrochloride form, in combination with cyclizine hydrochloride, is marketed as Diconal, indicated for relief of moderate to severe pain....
under the brand name
Diconal. IV'd cyclizine produces the strongest effects, although it can also be taken orally to achieve a more euphoric high.
Side effects
Common (>10%) - Drowsiness,
xerostomiaXerostomia is the medical term for the subjective complaint of dry mouth due to a lack of saliva. Xerostomia is sometimes colloquially called pasties, cottonmouth, doughmouth or des . Xerostomia is also common in smokers....
(dry mouth)
Uncommon (1% to 10%) - Headache, psychomotor impairment, and antimuscarinic effects such as
urinary retentionUrinary retention also known as ischuria is a lack of ability to urinate. It is a common complication of benign prostatic hypertrophy , although anticholinergics may also play a role, and requires a catheter or prostatic stent...
, diplopia (blurred vision), dermatitis, and gastro-intestinal disturbances.
Rare - Hypersensitivity reactions (bronchospasm, angioedema, anaphylaxis, rashes and photosensitivity reactions), extrapyramidal effects, dizziness, confusion, depression, sleep disturbances, tremor, liver dysfunction and hallucinations
Formulations
As cyclizine hydrochloride 50mg tablets and cyclizine lactate solution for intramuscular or intravenous injection (Brand names: Valoid in UK and Marezine, Marzine and Emoquil in US).