Dr Sharon Rees @reesprescribe
Day 1: #cyclizine is an antihistamine with its clinical niche as an antiemetic. It bears chemical similarity to the ‘piperine’ structure found in the black pepper plant. Developed in 1947, its popularity increased after NASA selected it to treat space sickness for the Apollo missions
Dr Sharon Rees @reesprescribe
Day 2: UK indications for #cyclizine include nausea, vomiting, vertigo, motion sickness, labyrinthine disorders and nausea and vomiting in palliative care. Oral, i.v., i.m, s.c (palliative); Adults 50–150 mg/day, children > 1month (dose variable, injection unlicensed + tablets < 6yr). Unlicensed use for morning sickness (if persistent symptoms)
Dr Sharon Rees @reesprescribe
Day 3: Mode of action; emetic stimuli, such as labyrinthine disturbance and triggers to vomiting centre/chemoreceptor trigger zone, evokes histamine 1(H1) + muscarinic M1 receptors. #cyclizine is an antagonist at both H1 and muscarinic receptors. Also CNS depressant but precise antiemetic mechanism unknown
Dr Sharon Rees @reesprescribe
Day 4: Kinetics #cyclizine; good oral absorption, effects within 30 mins lasting 4–6 hrs. Oral t½ 20 hours, i.v 13 hours. Elimination poorly understood; clearance believed to be extra-renal. Absence of detail in drug literature possibly because of age and/or quality of supporting data
Dr Sharon Rees @reesprescribe
Day 5: Low incidence of drowsiness, but unknown frequency for most #cyclizine ADRs, including insomnia, reduced appetite, nausea/vomiting, movement disorders, hallucinations (not exhaustive). Anti-cholinergic effects include urinary retention, constipation, dry mouth, blurred vision. CAUTIONS for #cyclizine include severe heart failure and epilepsy; NOTE #cyclizine can enhance opioid action re CNS depression
Dr Sharon Rees @reesprescribe
Day 6: #cyclizine drug–drug interactions; multiple moderate; severe (increased risks of antimuscarinic effects) with isocarboxazid, phenelzine, tranylcypromine. Additive effects with other CNS depressants including alcohol and may also enhance toxicity of alcohol. Care re anti-cholinergic burden
Dr Sharon Rees @reesprescribe
Day 7: i.v formulation of #cyclizine can cause euphoria and addiction. ‘Recreational’ use to induce psychoactive effects such as hallucinations, which are also promoted in combination with agents such as methadone. Has been associated with addictive behaviour