Amantadine Hydrochloride

Indications

Amantadine Hydrochloride is used for: Parkinson's disease, Influenza, herpes zoster, drug-induced extrapyramidal reactions

Adult Dose

Adult: PO Influenza A 100 mg/day for 5 days. Prophylaxis of influenza A 100 mg/day for up to 6 wk. W/ influenza vaccination: up to 3 wk after vaccination. Elderly: >65 yr: Daily dose of <100 mg or 100 mg given at intervals >1 day. Herpes zoster 100 mg twice daily for 14 days, may continue for another 14 days if pain persists. Parkinson's disease100 mg/day, up to 100 mg twice daily 1 wk or more. Max: 400 mg/day.

Child Dose

Oral Influenza A treatment Child: 1-9 years or <40 kg (any age): 5 mg/kg/day PO in single dose or divided q12 hr; not to exceed 150 mg/day >10 years and <40 kg: 5 mg/kg/day PO divided q12hr >10 years and >40 kg: 100 mg PO q12hr NOTE: Because of resistance, amantadine is no longer recommended for prophylaxis or treatment of influenza A

Renal Dose

Renal impairment: CrCl (ml/min) >35 100 mg daily. 15-35 100 mg every 2-3 days. <15 Not recommended.

Administration

Should be taken with food.

Contra Indications

Hypersensitivity. Pregnancy and lactation. Epilepsy or other seizure disorders, severe renal impairment and gastric ulceration.

Precautions

Patients with CV or liver disease, impaired renal function, recurrent eczema. Elderly. Withdrawal of the drug should be gradual. Lactation: Drug enters breast milk; not recommended

Pregnancy-Lactation

Pregnancy No adequate data on developmental risk associated with amantadine use in pregnant women; animal studies suggest a potential risk for fetal harm with amantadine; in mice and rats, adverse developmental effects (embryo lethality, increased incidence of malformations, and reduced fetal body weight) were observed when amantadine was administered to pregnant animals at clinically relevant doses In mice, oral administration of amantadine (0, 10, or 40 mg/kg/day) to pregnant animals during organogenesis (gestation days 7-12) resulted in embryo lethality and reduced fetal body weight at highest dose tested, which was associated with maternal toxicity; the no-effect dose for developmental toxicity in mice (10 mg/kg/day) is less than the recommended human dose (RHD) of 274 mg/day, based on body surface area (mg/m²) Lactation Amantadine is excreted into human milk, but amounts have not been quantified; there is no information on the risk to a breastfed infant; amantadine may alter breast milk production or excretion In published studies, amantadine reduced serum prolactin levels and symptoms of galactorrhea in patients taking neuroleptic drugs; the effect of amantadine on milk supply has not been evaluated in nursing mothers

Interactions

Enhances the adverse effects of antimuscarinics and levodopa. CNS stimulants, drugs that raise urinary pH. The concurrent use of Amantadine hydrochloride with live attenuated influenza vaccine (LAIV) intranasal has not been evaluated.

Adverse Effects

Side effects of Amantadine Hydrochloride : 1-10% Agitation, Anorexia, Anxiety, Ataxia, Confusion, Constipation, Depression, Diarrhea, Dizziness, Dream abnormality, Dry nose, Fatigue, Hallucinations, Headache, Insomnia, Irritability, Livedo reticularis, Nausea, Nervousness, Orthostatic hypotension, Peripheral edema, Somnolence, Xerostomia <1% Amnesia, CHF, Decreased libido, Dyspnea, Eczematoid dermatitis, Euphoria, Hyperkinesis, Hypertension, Instances of convulsions, Leukopenia, Neutropenia, Oculogyric episodes, Psychosis, Rash, Slurred speech, Urinary retention, Visual disturbances, Vomiting, Weakness Potentially Fatal: Congestive heart failure, convulsions.

Mechanism of Action

Amantadine is a weak dopamine agonist possessing antimuscarinic properties. It alters dopamine release and re-uptake. It also noncompetitively antagonises N-methyl-D-aspartate. As an antiviral drug, it inhibits replication of influenza type A virus.