Subcutaneous Refractory motor fluctuations in Parkinson's disease
Adult: Initially, 1 mg at the 1st sign of an "off" episode, then a further 2 mg if inadequate or no response after 30 min. Subsequent increments can be made at intervals of at least 40 min until satisfactory response obtained. Usual dose range: 3-30 mg daily in divided doses. Patient requiring >10 inj/day: Initially, 1 mg/hr via continuous SC infusion increased not more often than 4 hrly in max increments of 500 mcg/hr, to usual rate of 1-4 mg/hr (15-60 mcg/kg/hr). Should only be given during waking hr and change infusion site 12 hrly. Intermittent bolus inj may be required to supplement the infusion. Max: 100 mg/day and 10 mg/dose.
Renal Impairment
Mild to moderate: Reduce initial dose.
Contraindications
Patient w/ resp or CNS depression, neuropsychiatric problems, or dementia. Patient who has "on" response to levodopa marred by severe dyskinesia or dystonia.
Special Precautions
Patient prone to nausea and vomiting or when vomiting is likely to pose a risk. Patient w/ pulmonary, CV, or endocrine disease, history of orthostatic hypotension. Renal and hepatic impairment. Elderly or debilitated patients. Pregnancy and lactation.
Adverse Reactions
Yawning, dyskinesias, nausea and/or vomiting, somnolence, transient sedation, dizziness, oedema, chest pain, orthostatic hypotension, postural instability and falls, increased salivation and perspiration, neuropsychiatric disturbances. Signs of CNS stimulation (e.g. euphoria, lightheadedness, restlessness, tremor, tachycardia and tachypnoea). Induration, nodule formation, and panniculitis, sometimes leading to ulceration, often develops at the site of inj. Rarely, eosinophilia.
This drug may cause somnolence and/or an episode of sudden sleep onset, if affected do not drive or operate machinery.
Monitoring Parameters
Periodic monitoring of hepatic, renal, haematopoietic, and CV function.
Overdosage
Symptoms: Persistent vomiting, resp depression, bradycardia, hypotension, and coma; death may occur. Management: Excessive emesis may be treated w/ domperidone. An opioid antagonist (e.g. naloxone) has been given to treat CNS and resp depression. Appropriate measures must be taken (e.g. raising the foot of the bed) in case of hypotension. May use atropine in bradycardia.
Drug Interactions
May potentiate hypotensive effects of antihypertensives or organic nitrates. Antipsychotics and other drugs that act as CNS dopamine inhibitors may antagonise therapeutic effects of apomorphine. Additive effect on QT interval prolongation w/ drugs known to prolong the QT interval (e.g. TCAs, antipsychotic agents). May enhance effect w/ memantine and entacapone.
Food Interaction
Enhanced hypotensive effects w/ alcohol.
Action
Description: Mechanism of Action: Apomorphine is a nonergot-derivative potent dopamine D1- and D2-receptor agonist. It stimulates postsynaptic dopamine D2 receptors w/in the caudate-putamen in the brain. Onset: Rapid. Pharmacokinetics: Absorption: Well absorbed. Distribution: Volume of distribution: 218 L. Plasma protein binding: Approx 90% (mainly albumin). Metabolism: Undergoes conjugation w/ glucuronic acid or sulfate to its major metabolite apomorphine sulfate and demethylation to form norapomorphine. Excretion: Via urine (93%) as metabolites and faeces (16%). Terminal elimination half-life: 40 min.
Chemical Structure
Apomorphine Source: National Center for Biotechnology Information. PubChem Database. Apomorphine, CID=6005, https://pubchem.ncbi.nlm.nih.gov/compound/Apomorphine (accessed on Jan. 21, 2020)
Anon. Apomorphine. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 20/05/2014.Buckingham R (ed). Apomorphine Hydrochloride. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 20/05/2014.Joint Formulary Committee. Apomorphine Hydrochloride. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 20/05/2014.McEvoy GK, Snow EK, Miller J et al (eds). Apomorphine Hydrochloride. AHFS Drug Information (AHFS DI) [online]. American Society of Health-System Pharmacists (ASHP). https://www.medicinescomplete.com. Accessed 20/05/2014.
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