Osmolex Er

  • Parkinsonism

Osmolex Er Generic Name & Formulations

General Description

Amantadine HCl 129mg, 193mg; ext-rel tabs.

Pharmacological Class

Dopamine agonist.

How Supplied

Ext-rel tabs—30

Generic Availability


Mechanism of Action

The mechanism by which amantadine exerts efficacy in the treatment of Parkinson’s disease and drug-induced extrapyramidal reactions is unknown. Amantadine is a weak uncompetitive antagonist of the NMDA receptor; however, it exhibits anticholinergic-like side effects such as dry mouth, urinary retention, and constipation in humans. Amantadine may have direct and indirect effects on dopamine neurons.

Osmolex Er Indications


Treatment of Parkinson's disease and drug-induced extrapyramidal reactions.

Osmolex Er Dosage and Administration


Swallow whole. Initially 129mg once daily in the AM; may increase in weekly intervals to max 322mg once daily in the AM. Renal impairment (CrCl 30–59mL/min/1.73m2): initially 129mg once every 48hrs; increase every 3 weeks to max 322mg; (CrCl 15–29mL/min/1.73m2): initially 129mg once every 96hrs; increase every 4 weeks to max 322mg. Taper gradually from high doses to 129mg daily for 1–2 weeks before discontinuing.


Not established.

Osmolex Er Contraindications


End-stage renal disease (CrCl <15mL/min/1.73m2).

Osmolex Er Boxed Warnings

Not Applicable

Osmolex Er Warnings/Precautions


Not interchangeable with other amantadine products. Sleep disorders. Discontinue if daytime sleepiness or episodes of falling asleep during activities that require full attention develops. Monitor for depression, suicidal ideation or behavior. Psychotic disorders: not recommended. Monitor for hallucinations, dizziness, orthostatic hypotension (esp. at initiation and after dose increases). Monitor for new or increased urges or compulsive behaviors; consider reducing dose or discontinuing if develops. Avoid abrupt cessation. Monitor conditions (eg, renal tubular acidosis, severe UTIs) that can alter the urine pH (acidic or alkaline). Renal impairment. Elderly: monitor renal function. Pregnancy. Nursing mothers.

Osmolex Er Pharmacokinetics


Renal (~85%). Half-life: ~16 hours.

Osmolex Er Interactions


Concomitant alcohol, live attenuated vaccines: not recommended. Increased somnolence with concomitant sedatives. Potentiated by anticholinergics; reduce dose. Concomitant drugs affecting urinary pH (eg, carbonic anhydrase inhibitors, sodium bicarbonate); monitor.

Osmolex Er Adverse Reactions

Adverse Reactions

Nausea, dizziness/lightheadedness, insomnia; drowsiness, suicidality, depression, psychosis, withdrawal-emergent hyperpyrexia/confusion, impulse control/compulsive behavior.

Osmolex Er Clinical Trials

See Literature

Osmolex Er Note

Not Applicable

Osmolex Er Patient Counseling

See Literature