Apomorphine

• This is a dopamine agonist used for the management of motor symptoms of Parkinson's disease (PD).¹
• It has several different characteristics which mark it out from the rest of the dopamine agonist group used in the management of PD.
• It is given subcutaneously.
• It is structurally similar to dopamine and its use results in a rapid improvement in motor symptoms of PD by stimulation of dopaminergic receptors in substantia nigra.

• It is suitable for patients with advanced disease which is difficult to manage with levodopa. Age and disease duration does not affect efficacy.
• As a rescue agent to provide rapid but short-lived benefit for sudden, severe 'Off' episodes, to establish whether further benefit can be obtained by increasing the dose of oral agents.
• In patients unable to take oral medication due to acute illness or chronic dysphagia.
• In cases of diagnostic difficulty.

• The population in whom apomorphine can to most good is ironically the same in whom it can potentially do most harm i.e. elderly patients, who often have multisystem disease. However, a multicentre trial of 82 patients with a mean age of 67 years found a significant reduction in 'off' periods and severity of dyskinesia.⁵
• It is specifically contraindicated in neuropsychiatric conditions, dementia, or if 'On' response to levodopa is marred by severe dyskinesia, hypotonia or psychiatric effects.
• Monitoring for hepatic, renal, cardiovascular complications and haemolytic anaemia is required.

See Summary of Product Characteristics for full list.¹

Mainly nausea, vomiting and postural hypotension.

Apomorphine is antagonised by antipsychotics and methyldopa; it is enhanced by entacapone and memantine. See drug monograph for full list.

• Intermittent Subcutaneous Injections
  • These are used as rescue therapy for disabling 'Off' periods in patients taking oral therapy.¹¹
  • The 'Off' period can be averted or reversed within 10-15 minutes and can last for up to one hour.
  • They are suitable for patients who have short 'Off' periods less than six times a day. For more frequent episodes, continuous infusion should be considered.
  • Injections need to be given no later than the beginning of the 'Off' period.
  • Most patients can be taught to self-administer. Injection should be to lower abdominal wall below umbilicus, upper outer aspect thighs or outer aspect top of arms.
  • Patients should be advised to rotate the injection site and gently massage after administration, to avoid nodule formation.
  There are two ways to administer apomorphine. Choice governed by patient preference, condition and cost.
  • Pre-filled penject device (APO-go Pen®) - 30 mg in 3 ml, needs to be discarded every 48 hours but needle needs changing after each injection
  • Insulin-type syringe - patient prepares syringe using 2 ml (10 mg/ml) amp apomorphine, prepared on daily basis, discard unused syringe after 24 hours.
• Continuous Infusion
  • Indicated for patients with advanced disease who experience frequent unpredictable and disabling motor fluctuations and dyskinesias despite maximal oral therapy
  • Can be given as adjunct or monotherapy
  • Benefits comparable to deep brain stimulation of subthalamic nucleus
  • Most patients only need infusion during waking hours, a few need 24 hour therapy
  • Mean daily dosage range 50-100 mg per day
  • Initiation requires hospital admission to educate patient and monitor for side effects
  • Titration in community required, may take several months to obtain optimal dose and response
  • Used to be administered only by Sims-Graseby syringe driver
  • APO-go pump now available
  • Choice depends on patient preference and cost