Zanamivir

Indications

Zanamivir is used for: Prophylaxis & treatment of Influenza A and B virus infection

Adult Dose

Inhalation Influenza A and B Adult: 10 mg (2 inhalations) bid for 5 days, admin as soon as possible (within 48 hr) after the onset of symptoms. 2 doses should be taken on 1st day of treatment provided there is at least an interval of at least 2 hr between doses, subsequent doses to be given every 12 hr. Prophylaxis of influenza A and B Adult: For community outbreak: 10 mg (2 inhalations) once daily for 28 days, to be started within 5 days of outbreak. For prophylaxis in household setting: 10 mg (2 inhalations) once daily for 10 days, to be started within 36 hr of exposure.

Child Dose

Inhalation Influenza A and B Child: >7 yr: 10 mg (2 inhalations) bid for 5 days, admin as soon as possible (within 48 hr) after the onset of symptoms. 2 doses should be taken on 1st day of treatment, if possible, provided there is at least an interval of at least 2 hr between doses, subsequent doses to be given every 12 hr. Inhalation Prophylaxis of influenza A and B Child: For community outbreak: >12 yr: 10 mg (2 inhalations) once daily for 28 days, started within 5 days of outbreak. For prophylaxis in household setting: ?5 yr: 10 mg (2 inhalations) once daily for 10 days, to be started within 36 hr of exposure.

Renal Dose

Administration

Contra Indications

Hypersensitivity.

Precautions

Pregnancy, lactation. High risk of bronchospasm in chronic respiratory diseases. Fast-acting bronchodilator should be readily available for asthma/COPD patients; avoid in severe asthma. Bronchodilators to be inhaled before zanamivir admin. Discontinue if bronchospasm develops or there is decrease in respiratory function.

Pregnancy-Lactation

Pregnancy Available data from published studies suggest that use during pregnancy is not associated with an increased risk of birth defects or adverse maternal or fetal outcomes; however, these studies are limited by their small sample sizes, which preclude a definitive assessment of the risk; there are risks to mother and fetus associated with influenza infection in pregnancy; in animal reproduction studies, no adverse developmental effects were observed with intravenous or subcutaneous administration of zanamivir at exposures 300 and 150 times, respectively, the systemic exposure at the maximum recommended human inhalation dose (MRHID) of 10 mg twice daily Pregnant women are at higher risk of severe complications from influenza, which may lead to adverse pregnancy and/or fetal outcomes, including maternal death, stillbirths, birth defects, preterm delivery, low birth weight,and small for gestational age Lactation There are no data on presence of zanamivir in human milk or effects on milk production; there are data from adults that have shown low oral bioavailability of zanamivir; limited data from postmarketing case reports have not suggested a safety concern in infants exposed to breast milk of mothers receiving therapy; drug was present in milk of lactating rats without effect on nursing pups; developmental and health benefits of breastfeeding should be considered along with mother’s clinical need for therapy and any potential adverse effects on breastfed child from drug or underlying maternal condition

Interactions

Do not admin live attenuated influenza vaccine intranasal within 2 wk before or 48 hr after zanamivir admin to improve response to vaccine.

Side Effects

Side effects of Zanamivir : >10% Headache (13-24%), Throat/tonsil pain (8-19%), Cough ( 7-17%), Viral infection (3-13%) >1% Dizziness (2%), Nausea (3%), Diarrhea (3% adults, 2% children), Vomiting (1% adults, 2% children), Sinusitis (3%), Bronchitis (2%), Infection (ear, nose, & throat; 2% adults, 5% children) <1% Malaise, Fatigue, Fever, Abdominal pain, Myalgia, Arthralgia, Urticaria

Mode of Action

Zanamivir, a sialic acid derivative, potentially inhibits viral neuraminidase of influenza virus, thus altering virus particle aggregation and release. It is active against influenza A and B virus replication.