Osmolex Er (amantadine HCl)
Last reviewed · Source: First Databank (FDB) drug data
Overview
Amantadine hydrochloride is a synthetic adamantane derivative that has pharmacologic activity as an anti-Parkinson and antiviral agent.
The exact mechanism of action of amantadine hydrochloride in the treatment of parkinsonian syndrome and drug-induced extrapyramidal reactions is not known. Amantadine does not appear to have direct anticholinergic activity; however, the drug causes anticholinergic-like effects such as dry mouth, urinary retention, and constipation. Amantadine is a weak uncompetitive antagonist of the NMDA receptor and may have direct and indirect effects on the dopaminergic system.
Amantadine hydrochloride is well absorbed from the GI tract. While peak plasma concentrations are directly related to amantadine hydrochloride dosages up to 200 mg daily, dosages exceeding 200 mg daily may result in a greater than proportional increase in peak plasma concentration. While amantadine principally is excreted unchanged in urine by glomerular filtration and tubular secretion, at least 8 metabolites have been identified in urine.
The elimination half-life of amantadine has been variously reported as 9-37 hours, with an average of 24 hours or less. Amantadine is only minimally removed by hemodialysis; in patients with renal failure who received a single 300-mg oral dose of amantadine hydrochloride, only 5% or less of the dose was removed into the dialysate following a 4-hour period of hemodialysis.
Following oral administration of amantadine as the extended-release capsules, dose-proportional pharmacokinetics were observed over the dose range of 68.5-274 mg. Time to peak plasma concentration after a single dose is approximately 12 hours and steady-state concentrations are achieved in 4 days. Food does not affect amantadine pharmacokinetics when given as the extended-release capsules; administration of capsule contents with applesauce also did not affect pharmacokinetics of the drug.
USES: This medication is used to treat Parkinson's disease. It is also used to treat certain movement disorders caused by some drugs (extrapyramidal reactions). This medication is thought to work by restoring the balance of certain natural substances (neurotransmitters) in the brain.
Different brands of this medication may have different uses. Do not change brands of this medication unless directed by your doctor.
Generic name: amantadine HCl
Pronunciation: (a-MAN-ta-deen)
Reference product & biosimilars
No reference, biosimilar or interchangeable associated with this drug.
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Indications
The following indications are listed for Osmolex Er:
- Drug-Induced Extrapyramidal Reaction
- Idiopathic Parkinsonism
Also known as: Drug-Induced Extrapyramidal Symptom, Paralysis Agitans, Primary Parkinson's Disease.
Dosing
Dosage of amantadine hydrochloride conventional tablets, capsules, and oral solution is expressed in terms of amantadine hydrochloride; dosage of amantadine hydrochloride extended-release capsules is expressed in terms of amantadine.
Amantadine hydrochloride is administered orally as conventional (i.e., immediate-release) tablets, conventional capsules, extended-release capsules,or a conventional oral solution.
No dosing information is available for this tab.
No dosing information is available for this tab.
Drug interactions
In vitro studies indicate that amantadine does not significantly inhibit the enzyme activity of drug metabolizing cytochrome P-450 (CYP) isoenzymes 1A2, 2B6, 2C19, 2C8, 2C9, 2D6, 2E1, 3A4, and 3A5.
Amantadine has negligible or no inhibitory activity against cellular transporters (P-gp, BCRP, MATE2-K, OAT1, OAT3, OATP1B1, and OATP1B3) at clinically relevant plasma concentrations.
There are no contraindication interactions for this drug.
There are no severe interactions for this drug.
There are no moderate interactions for this drug.
Contraindications
*Patients with known hypersensitivity to amantadine hydrochloride or any ingredients in the formulations.
There are no contraindication contraindications for this drug.
There are no severe contraindications for this drug.
There are no moderate contraindications for this drug.
Adverse reactions
The most common adverse effects (5-10%) of amantadine administered as conventional (immediate-release) preparations include nausea, dizziness, and insomnia.
The most common adverse effects (>10%) with extended-release amantadine capsules include hallucination, dizziness, dry mouth, peripheral edema, constipation, fall, and orthostatic hypotension.
There are no severe adverse reactions for this drug.
There are no less severe adverse reactions for this drug.
Precautions
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Safety and efficacy of amantadine for the treatment of parkinson disease have not been established in pediatric patients; the majority of individuals with parkinson disease are 65 years of age or older. When used in children, amantadine has caused CNS symptoms, which resolved when the drug was discontinued. An increased incidence of seizures has been reported in children with an underlying seizure disorder receiving amantadine.
Amantadine has been reported to be embryotoxic/teratogenic in rats when administered in dosages of 50 and 100 mg/kg daily (1.5 and 3 times, respectively, the maximum recommended human dosage on a mg/m2 basis), but not when administered in a dosage of 37 mg/kg daily (the maximum recommended human dosage on a mg/m2. One woman with a movement disorder similar to parkinsonian syndrome who may have been treated with amantadine hydrochloride (100 mg daily) during the first trimester of pregnancy delivered a child with a complex cardiovascular lesion (single ventricle and pulmonary atresia) that may have been caused by the drug. There are no adequate and well-controlled studies using amantadine in pregnant women, and the drug should be used during pregnancy only when the potential benefits outweigh the possible risks to the fetus.
Because amantadine is distributed into human milk, some manufacturers state that the drug should not be used in nursing women.
Dosage of amantadine conventional preparations should be reduced in geriatric patients 65 years of age or older. The manufacturer of the extended-release capsules states that no dosage adjustment is required based on age; however, because elderly patients are more likely to have decreased renal function, care should be taken to select dosage with caution and it may be useful to monitor renal function.
The majority of individuals with parkinson disease are 65 years of age or older. Clearance of amantadine is reduced, plasma concentrations of the drug are increased, and elimination half-life may be prolonged in healthy geriatric adults compared with healthy young adults.
Reduced dosages may be needed in geriatric patients >=65 years of age because of renal decline in such patients.
ICD codes
No ICD codes are available for this drug.
Formulary status
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Last reviewed · Source: First Databank (FDB) drug data
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