pramipexole dihydrochloride

Action

Unknown. May directly stimulate post-synaptic dopamine receptors in corpus striatum (unlike levodopa, which may increase brain's dopamine concentration).

Availability

Tablets: 0.125 mg, 0.25 mg, 0.5 mg, 0.75 mg, 1 mg, 1.5 mg

Tablets (extended-release): 0.375 mg, 0.75 mg, 1.5 mg, 2.25 mg, 3 mg, 3.75 mg, 4.5 mg

Indications and dosages

➣ Idiopathic Parkinson's disease

Adults: Initially, 0.125 mg P.O. t.i.d.; may increase by 0.125 mg q 5 to 7 days over 6 to 7 weeks. Maintenance dosage ranges from 1.5 to 4.5 mg/day in three divided doses. Or, 0.375 mg (extended-release) P.O. daily; may increase no more frequently than every 5 to 7 days, first to 0.75 mg/day and then by 0.75-mg increments up to a maximum recommended dosage of 4.5 mg/day. Assess therapeutic response and tolerability at a minimal interval of 5 days or longer after each dose increment.

➣ Moderate to severe primary restless leg syndrome

Adults: Initially, 0.125 mg P.O. once daily 2 to 3 hours before bedtime. For patients requiring additional symptomatic relief, increase dosage as needed every 4 to 7 days, up to dosage of 0.5 mg once daily.

Dosage adjustment

• Renal impairment

Contraindications

• Hypersensitivity to drug or its components

Precautions

Use cautiously in:

• renal impairment

• elderly patients

• pregnant or breastfeeding patients

• children (safety not established).

Administration

• Administer extended-release tablets whole.

• Know that patients may be switched overnight from immediate-release tablets to extended-release tablets at the same daily dose; however, dosage adjustment may be needed in some patients.

• Don't give at same time as other CNS depressants.

• Don't stop therapy abruptly. Taper dosage over 1 week.

Adverse reactions

CNS: headache, dizziness, drowsiness, hallucinations, asthenia, confusion, dyskinesia, insomnia, hypertonia, unsteadiness, sleep attacks, abnormal dreams, amnesia

CV: orthostatic hypotension

EENT: retinal deterioration

GI: nausea, constipation, dyspepsia, dry mouth

GU: urinary frequency, erectile dysfunction

Musculoskeletal: leg cramps

Respiratory: fibrotic complications (such as retroperitoneal fibrosis, pulmonary infiltrates, pleural effusion or thickening)

Skin: rhabdomyolysis (immediate release tablets)

Other: accidental injury, edema

Interactions

Drug-drug. Cimetidine: increased pramipexole blood level

Dopamine antagonists (such as butyro-phenones, metoclopramide, phenothia-zines, thioxanthenes): decreased pramipexole efficacy

Levodopa: increased risk of hallucinations and dyskinesia

Patient monitoring

• Evaluate patient for therapeutic and adverse effects.

• Assess blood pressure; watch for orthostatic hypotension.

• Monitor neurologic status, especially for sleep attacks and extrapyramidal symptoms.

• Watch closely for pulmonary complications.

Patient teaching

• Instruct patient to take drug with food if it causes nausea. Tell him not to take at same time as other CNS depressants.

• Instruct patient to swallow extended-release tablets whole and not to chew, crush, or divide them.

• Advise patient to report respiratory problems, dyskinesia, hallucinations, and sleep attacks.

• Tell patient drug may cause erectile dysfunction. Encourage him to discuss this effect with prescriber.

• Inform patient and family that drug's neurologic and motor effects increase risk of sudden onset of sleep without warning and accidental injury. Teach them ways to prevent injury.

See Advise patient and family to contact prescriber if vision changes or unexplained muscle pain, tenderness, or weakness occurs.

• Tell patient to move slowly when sitting up or standing, to avoid dizziness from sudden blood pressure decrease.

• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs mentioned above.