| Amantadine Pharmacology |
| Amantadine |
| About Amantadine |
| Dopamine Agonist, Anti-Parkinson`s Agent, Antiviral Agent. |
| Mechanism of Action of Amantadine |
| Antiviral action: Amantadine inhibits entry and uncoating of Influenza A virus. Amantadine prevents penetration and it binds to the membrane protein (M 2 protein) of Influenza A virus which allows influx of hydrogen ion in to the endosome of virus and cause pH dependent activation of haemagglutinin fusion and this fusion is essential for virus uncoating.. Antiparkinsonian action: Amantadine releases Dopamine from the substantia nigra and it cause increased concentration of Dopamine. This will produces antiparkinsonian effect. |
| Pharmacokinets of Amantadine |
| Absorption: Amantadine is well absorbed after oral administration. Distribution: It is widely distributed in the body. Metabolism: It undergoes insignificant metabolism. Excretion: The drug is excreted primarily through urine. Small amount of drug is excreted through breast milk. |
| Onset of Action for Amantadine |
| 4 hours |
| Duration of Action for Amantadine |
| 12-18 hours |
| Half Life of Amantadine |
| 20 hours |
| Side Effects of Amantadine |
| 1. Insomnia 2.Light headedness 3.Dizziness 4.Nausea 5.Anorexia 6.Vomiting 7.Nervousness |
| Contra-indications of Amantadine |
| 1.Hypersensitivity 2.Closed angle glaucoma |
| Special Precautions while taking Amantadine |
| 1. Renal impairment 2.Hepatic impairment 3.Heart failure 4.Convulsive patients 5.Mental illness 6. Hypotension 7.Allergy |
| Pregnancy Related Information |
| Use with caution |
| Old Age Related Information |
| Use with caution |
| Breast Feeding Related Information |
| Use with caution. |
| Children Related Information |
| Use with caution Children <1 year: contraindicated |
| Indications for Amantadine |
| 1.Prophylaxis and treatment of influenza A virus 2.Idiopathic Parkinsonism 3.Drugs induced extra pyramidal reactions |
| Interactions for Amantadine |
| Antihypertensives: methyldopa, reserpine: Extrapyramidal side effects. Anticholinergic drugs: Enhances the adverse effects of anti-cholinergics. Hydrochlorothiazide plus Triamterene: Urniary excretion of amantadine decreased. Antipsychotics, Metoclopropamide, Tetrabenazine & Domperidone: All have extrapyramidal side effects. |
| Typical Dosage for Amantadine |
| Adult: 200 mg / day Prophylaxis and treatment of influenza A virus: 200 mg / day in single dose or 2 divided doses. Idiopathic Parkinsonism: 100 – 200 mg / day Drugs induced extra pyramidal reactions: 100 mg 1 – 3 times daily depending on the severity of infection. Children above 10years: same as adult dose Children: 1 – 9 years: 4.4 mg/kg body weight given once or twice daily |
| Schedule of Amantadine |
| H |
| Storage Requirements for Amantadine |
| Store at 15 – 30 degree C in a tightly closed container. Keep out of the reach of children |
| Effects of Missed Dosage of Amantadine |
| Take the missed dose as soon as noticed and if it is the time for next dose then skip the missed dose.Continue the regular dose. |
| Effects of Overdose of Amantadine |
| Give supportive measures and symptomatic treatment. Drug can be removed from the body by inducing emesis or by gastric lavage |