• Ensure that any requested changes to repeat medication have been made since the last specialist visit, and check that doses and timings are correct.
• Check that any relevant drug monitoring has been undertaken if there is a local agreement for monitoring to take place in primary care.
• Ask about and monitor adherence to treatment and explore any barriers to taking medication.
• If the person is over-using dopaminergic medication, consider whether they may have dopamine dysregulation syndrome (compulsive overuse of dopaminergic drugs) — see Impulse control and related disorders.
• The National Institute for Health and Clinical Excellence has issued guidance on Medicines adherence: involving patients in decisions about prescribed medicines and supporting adherence that can be found at www.nice.org.uk.
• Ask about possible adverse effects of anti-parkinsonian medication.
• Ensure that no other medication is exacerbating the Parkinson's disease — see Drugs to avoid.
• Do not stop anti-parkinsonian medication abruptly because of the risk of causing neuroleptic malignant syndrome (which can be serious).
• Respond to any concerns about motor and non-motor symptoms of Parkinson's disease.
• Check that the person has appropriate access to support services — see Role of primary care.

In depth

Contact the person's Parkinson's disease specialist team if the following adverse effects of anti-parkinsonian medication occur, as alterations to the medication may be needed:

• Fibrotic reactions (such as cardiac valvulopathy and retroperitoneal fibrosis) related to ergot-derived dopamine agonists (bromocriptine, cabergoline, or pergolide).
• Nausea and vomiting related to anti-parkinsonian medication.
• Motor complications, including motor fluctuations and dyskinesias.
• Dystonic or akathisia-related pain.
• Neuropsychiatric symptoms, including:
• Cognitive impairment.
• Daytime hypersomnolence or excessive drowsiness.
• Impulse control and related disorders, such as hypersexuality, pathological gambling, or compulsive buying.
• Psychotic symptoms, confusion, and vivid dreaming.
• Sleep disturbance.
• Autonomic disturbances.
• Diarrhoea:
• May be caused by entacapone and tolcapone (catechol-O-methyltransferase inhibitors).
• Dose reduction or, if severe, discontinuation may be considered.
• Excessive saliva (sialorrhoea).
• Excessive sweating (hyperhidrosis).
• Hypotension and Postural (orthostatic) hypotension.
• Peripheral oedema:
• May occur with amantadine and dopamine agonists, but is not dose dependent.
• Diuretics or discontinuation of the offending medication may be considered.
• Weight loss.

The following adverse effects can initially be managed in primary care, but liaison with or referral to the person's Parkinson's disease specialist team may be needed if initial measures fail:

• Constipation.
• Nausea and vomiting unrelated to anti-parkinsonian medication.

In depth

• If possible, avoid the following drugs because they can worsen parkinsonism:
• The anti-emetics, metoclopramide and prochlorperazine.
• Anti-psychotics:
• On specialist advice only, clozapine may be used to treat psychosis in people with Parkinson's disease. Quetiapine appears to be well-tolerated with a good safety profile, but may not be effective for psychosis in people with Parkinson's disease.
• Some other drugs can also, less commonly, cause parkinsonism — see Differential diagnosis.
• If possible, also avoid the following drug combinations:
• Erythromycin and clarithromycin significantly increase the bioavailability of bromocriptine and cabergoline. Azithromycin would not be expected to interact.
• Ciprofloxacin significantly increases the bioavailability of ropinirole. Use an alternative antibiotic, or seek specialist advice about dose adjustment.
• Cough and cold preparations containing sympathomimetics (pseudoephedrine, ephedrine) should not be used with rasagiline or selegiline (risk of hypertension). Preparations containing dextromethorphan (a cough suppressant) should also not be used (risk of serotonin syndrome). People taking bromocriptine should also avoid sympathomimetics (increased risk of hypertension).
• Advise people to check with the pharmacist before purchasing over-the-counter cough and cold remedies.
• Pethidine should not be given with selegiline or rasagiline, or for 2 weeks after stopping these drugs.
• Some antidepressant drugs should not be used with some drugs for Parkinson's disease:
• People taking rasagiline or selegiline should not use selective serotonin reuptake inhibitors, venlafaxine, duloxetine, sor tricyclic antidepressants. Trazodone or mirtazapine may be cautiously used (off-label use for selegiline).
• See Drug treatment of depression for details.

In depth