Tamiflu manufactured by ROCHE

active principle Oseltamivir Phosphate

Drug Nomenclature Synonyms: GS-4104/002; Oseltamivir, fosfato de; Ro-64-0796/002 USAN: Oseltamivir Phosphate rINNM: Oseltamivir Phosphate erINNM: Fosfato de oseltamivir Chemical name: Ethyl (3R,4R,5S)-4-acetamido-5-amino-3-(1-ethylpropoxy)-1-cyclohexene-1-carboxylate phosphate (1:1) Molecular formula: C16H28N2O4,H3PO4 =410.4 CAS: 196618-13-0 (oseltamivir); 204255-11-8 (oseltamivir phosphate) WHO ATC code: J05AH02

Adverse Effects The most commonly reported adverse effects associated with oseltamivir are nausea and vomiting, abdominal pain, bronchitis, insomnia, and vertigo. Diarrhoea, dizziness, headache, cough, and fatigue may occur, but many adverse effects may be difficult to distinguish from the symptoms of influenza. Other adverse effects occurring less commonly have included unstable angina, anaemia, pseudomembranous colitis, pneumonia, pyrexia, and peritonsillar abscess. There have been occasional reports of skin rash and, rarely, elevated liver enzymes and hepatitis.

Precautions Oseltamivir is not recommended in patients with severe renal impairment and it should be given with caution and dosage should be reduced in patients with moderate renal impairment (see Administration in Renal Impairment, ).

Pharmacokinetics Oseltamivir is readily absorbed from the gastrointestinal tract following oral administration and is extensively metabolised in the liver to the active entity, oseltamivir carboxylate. At least 75% of an oral dose reaches the systemic circulation as the carboxylate. Binding to plasma proteins is about 3% for the carboxylate and 42% for the parent drug. Oseltamivir has a plasma half-life of 1 to 3 hours. The carboxylate is not metabolised further and is eliminated in the urine.

Uses and Administration Oseltamivir is an oral prodrug of oseltamivir carboxylate, an inhibitor of the enzyme neuraminidase (sialidase), which has a role in the infectivity and replication of influenza A and B viruses. It is used for the treatment and prevention of influenza A and B.

For treatment, oseltamivir is given as the phosphate, but doses are expressed in terms of the base. Oseltamivir phosphate 98.5 mg is approximately equivalent to 75 mg of oseltamivir. The usual adult dose is 75 mg twice daily for 5 days, beginning as soon as possible (within 48 hours) after the onset of symptoms.

For the prevention of influenza, the adult dose is 75 mg once daily for at least 7 days for postexposure prophylaxis and for up to 6 weeks during an epidemic; therapy should begin within 48 hours of exposure.

Doses in children over 1 year for the treatment of influenza are, according to body-weight: over 40 kg, the adult dose; 23 to 40 kg, 60 mg twice daily; 15 to 23 kg, 45 mg twice daily; less than 15 kg, 30 mg twice daily.

Dosage should be reduced in patients with moderate renal impairment (see ).

Treatment

CC 10 to 30 mL/minute: treatment of influenza: 75 mg once daily or 30 mg twice daily; prevention: 75 mg on alternate days or 30 mg daily

CC less than 10 mL/minute: not recommended

more details under www.goldpharma.com [1]