What Makes OSMOLEX® ER (amantadine) Unique?

OSMOLEX ER has a consistent pharmacokinetic profile with the Osmodex® delivery system that delivers amantadine1,2

When taken in the morning, amantadine plasma levels are higher during the day,
without any mid-day trough effect.2

Comparison of OSMOLEX ER to immediate-release amantadine2

Hourglass Icon The Osmodex delivery system can provide a controlled and steady increase in amantadine after administration.2

  • There are no head-to-head studies in patients with PD comparing the safety and efficacy of OSMOLEX to that of amantadine IR.
  • PK data do not provide evidence of clinical safety or efficacy.

These data come from a single-center, laboratory-blinded, randomized, 2-treatment, 2-period, 2-sequence, multiple oral dose crossover study was conducted in 24 healthy volunteers to compare 258-mg OSMOLEX ER tablets to 258-mg amantadine oral syrup.2

The efficacy of OSMOLEX ER has been established based on bioavailability studies that compared OSMOLEX ER to immediate-release amantadine.1,2

The pharmacokinetics of OSMOLEX ER across 3 different dosage strengths were shown to be dose proportional.1,2


Multiple dosing options

Every patient is unique, so multiple dosing options allow you to tailor treatment to each individual patient’s needs.

Chart comparing the size and dosing options available for OSMOLEX® ER (amantadine) Chart comparing the size and dosing options available for OSMOLEX® ER (amantadine)

Actual tablet size relative to a penny.

The recommended initial dose of OSMOLEX ER is 129 mg taken orally once-a-day in the morning.1

The dosage may be increased in weekly intervals to a maximum daily dose of 322 mg (administered as a 129-mg and a 193-mg tablet).1

Warning icon

OSMOLEX ER is not interchangeable
with other amantadine immediate-
or extended-release products1

Kidney icon

There are no modifications for the recommended initial
and maximum dosage in patients with renal impairment;
however, modifications are recommended for the
titration interval and frequency of dosing in patients
with moderate and severe renal impairment1

Food and drink icon

OSMOLEX ER can be taken with or
without food. OSMOLEX ER should be
swallowed whole. Do not crush, chew,
or divide the tablet1

Quick Reference Dosing: OSMOLEX ER Amantadine HCl Equivalence1

OSMOLEX® ER (amantadine) logo Amantadine HCI Equivalent
129 mg 160 mg
193 mg 240 mg
258 mg 320 mg
322 mg
(taken as 2 tablets: 129 mg + 193 mg)
400 mg

NOTE: The USP Salt Policy (May 2013) requires the name and strength of the active ingredient in a drug product to be expressed in terms of the active moiety rather than the salt strength equivalent.3

Incidence of Adverse Reactions From Pooled Studies of Immediate-Release Amantadine1

Incidence Rate Adverse Reaction
5% to 10% Nausea, dizziness/lightheadedness, insomnia
1% to 5% Depression, anxiety and irritability, hallucinations, confusion, anorexia, dry mouth, constipation, ataxia, livedo reticularis, peripheral edema, orthostatic hypotension, headache, somnolence, nervousness, dream abnormality, agitation, dry nose, diarrhea, fatigue
0.1% to 1% Congestive heart failure, psychosis, urinary retention, dyspnea, skin rash, vomiting, weakness, slurred speech, euphoria, thinking abnormality, amnesia, hyperkinesia, hypertension, decreased libido, visual disturbance, punctate subepithelial or other corneal opacity, corneal edema, decreased visual acuity, sensitivity to light, optic nerve palsy
Less than 0.1% Convulsion, leukopenia, neutropenia, eczematoid dermatitis, oculogyric episodes, suicidal attempt, suicide, suicidal ideation


  1. OSMOLEX ER. Prescribing information. Vertical Pharmaceuticals, LLC; 2020.
  2. DeVries T, Dentiste A, Handiwala L, Jacobs D. Bioavailability and pharmacokinetics of once-daily amantadine extended-release tablets in healthy volunteers: results from three randomized, crossover, open-label phase 1 studies. Neurol Ther. 2019. DOI: 10.1007/s40120-019-0144-1.
  3. Center for Drug Evaluation and Research. Naming of drug products containing salt drug substances: guidance for industry. US Food and Drug Administration website. https://www.fda.gov/downloads/drugs/guidancecomplianceregulatoryinformation/guidances/ucm379753.pdf. Published June 2015. Accessed March 23, 2018.