Cyclizine

Cyclizine may have additive effects with alcohol and other central nervous system depressants e.g. hypnotics, tranquillisers, anaesthetics, antipsychotics, barbiturates.

Cyclizine should be used with caution in patients with severe heart failure or acute myocardial infarction. In such patients, cyclizine may cause a fall in cardiac output associated with increases in heart rate, mean arterial pressure and pulmonary wedge pressure.

Cyclizine may mask the warning signs of damage caused by ototoxic drugs such as aminoglycoside antibacterials.

Cyclizine may counteract the haemodynamic benefits of opioid analgesics.

Because of its anticholinergic activity cyclizine may enhance the side-effects of other anticholinergic drugs, and have an additive antimuscarinic action with other antimuscarinic drugs, such as atropine and some antidepressants (both tricyclics and MAOIs).

Cyclizine enhances the soporific effect of pethidine.

As with other anticholinergic agents, cyclizine may precipitate incipient glaucoma and it should be used with caution and appropriate monitoring in patients with glaucoma, urinary retention, obstructive disease of the gastrointestinal tract, hepatic disease, phaeochromocytoma, hypertension, epilepsy and in males with possible prostatic hypertrophy.

Cyclizine should be avoided in porphyria.

In the absence of any definitive human data, the use of cyclizine in pregnancy is not advised.

Cyclizine is excreted in human milk, however, the amount has not been quantified.

Fertility

In a study involving prolonged administration of cyclizine to male and female rats, there was no evidence of impaired fertility after continuous treatment for 90-100 days at dose levels of approximately 15 and 25 mg/kg/day. There is no experience of the effect of cyclizine on human fertility.

Studies designed to detect drowsiness did not reveal sedation in healthy adults who took a single oral therapeutic dose (50 mg) of cyclizine. Patients should not drive or operate machinery until they have determined their own response. Although there are no data available, patients should be cautioned that cyclizine may have additive effects with alcohol and other central nervous system depressants, e.g. hypnotics and tranquillisers.

Adverse reactions are ranked under heading of frequency, the most frequent first, using the following convention: Very common: (≥1/10); Common (≥1/100 to <1/10); Uncommon (≥1/1,000 to <1/100); Rare (≥1/10,000 to <1/1,000); Very rare (<1/10,000); Not known: cannot be estimated from the available data.

Blood and lymphatic system disorders

Not known: Agranulocytosis, leucopenia, haemolytic anaemia, thrombocytopenia

Cardiac disorders

Not known: Tachycardia, palpitations, arrhythmias

Ear and labyrinth disorder

Not known: Tinnitus

Eye disorders

Not known: Blurred vision, oculogyric crisis

Gastrointestinal disorders

Not known: Dryness of the mouth, nose and throat, constipation increased gastric reflux. Nausea, vomiting, diarrhoea stomach pain. Loss of appetite

General disorders and administration site conditions

Not known: Asthenia

Hepatobiliary disorders

Not known: Hepatic dysfunction including hepatitis due to hypersensitivity.
Cholestatic jaundice and cholestatic hepatitis have occurred in association with cyclizine.

Immune system disorders

Not known: Hypersensitivity reactions, including anaphylaxis have occurred

Musculoskeletal and connective tissue disorders

Not known: Twitching, muscle spasms

Nervous system disorders

Not known: Effects on the central nervous system have been reported with cyclizine these include somnolence, drowsiness, incoordination headache, dystonia, dyskinesia, extrapyramidal motor disturbances, tremor, convulsions, dizziness, decreased consciousness, transient speech disorders, paraesthesia and generalised chorea*

Psychiatric disorders

Not known: Disorientation, restlessness, nervousness, euphoria, insomnia and auditory and visual hallucinations have been reported, particularly when dosage recommendations have been exceeded

Renal and urinary disorders

Not known: Urinary retention

Respiratory, thoracic and mediastinal disorders

Not known: Bronchospasm, apnoea

Skin and subcutaneous tissue disorders

Not known: Urticaria, drug rash, angioedema, allergic skin reactions, fixed drug eruption photosensitivity

Vascular disorders

Not known: Hypertension, hypotension

^* There have been rare case reports of patients experiencing depressed levels of consciousness/loss of consciousness. The use of cyclizine has been associated with cases of paralysis following administration of the intravenous formulation of the medicine. The onset of paralysis is usually within minutes of administration, affects the limbs, and fully resolves within hours of discontinuation of the medicine.

IV formulation only:

Blisters at the site of injection and pruritus, as well as sensation of heaviness, chills, agitation, flushing and hypotension have been reported.

Rapid IV administration can lead to symptoms similar to overdose.