What role could TAMIFLU play in a pandemic?
TAMIFLU to play dual role: prevention and treatment
The antiviral TAMIFLU could play two principal roles in the management of seasonal flu: prophylaxis, aimed at decreasing the likelihood of developing flu, and treatment, aimed at reducing the duration of flu by 1.3 days. Research has demonstrated the effectiveness of antivirals when used for both purposes. When used for treatment purposes, these drugs need to be administered within 48 hours after the onset of symptoms.
Experts recommend TAMIFLU for pandemic flu management
- The Centers for Disease Control and Prevention (CDC) provides interim guidelines that identify TAMIFLU, in the absence of sensitivity testing, as the “first choice” for antiviral protection of workers involved in activities to control and eradicate outbreaks of influenza among poultry in the United States. For more information, visit http://www.cdc.gov/flu/avian/index.htm
- The World Health Organization recommends TAMIFLU for the prevention of pandemic influenza disease in household contacts. This recommendation is based on the effectiveness of TAMIFLU in preventing ordinary influenza in healthy and elderly patients and children ages 1 year and older.
- Recent studies, based on mathematical modeling, suggest that antivirals like TAMIFLU could be used prophylactically near the start of a pandemic to reduce the risk that a fully transmissible virus will emerge—or at least to delay its spread internationally—thus gaining time to augment vaccine supplies. The success of this strategy, which has never been tested, depends on several assumptions about the early behavior of a pandemic virus, which cannot be known in advance. Success also depends on excellent surveillance and logistics capacity in the initially affected areas, combined with an ability to enforce movement restrictions in and out of the affected area. To increase the likelihood that early intervention using the WHO rapid-intervention stockpile of antiviral drugs will be successful, surveillance in affected countries needs to improve, particularly concerning the capacity to detect clusters of cases closely related in time and place.
TAMIFLU: one of two antivirals for pandemic flu
Both TAMIFLU and Relenza (zanamivir) are currently being stockpiled as part of the federal government’s pandemic preparedness plan.22 TAMIFLU is available in capsule and suspension form, while Relenza is available in dry powder form via an inhaled delivery system. Both drugs are indicated for the prevention and treatment of influenza in adults and children (Tamiflu ³1 year; Relenza ³7 years for treatment, ³5 years for prevention).
It should be noted that TAMIFLU, based on number of prescriptions, is the flu antiviral most frequently prescribed by physicians. Of both neuraminidase inhibitors, TAMIFLU currently holds 99% of the market share.
Experts look to neuraminidase inhibitors for pandemic flu
- TAMIFLU and Relenza are antivirals that belong to a drug class known as neuraminidase inhibitors. In laboratory studies, the neuraminidase inhibitors have been shown to reduce the duration of illness caused by seasonal influenza. The efficacy of the neuraminidase inhibitors depends on their administration within 48 hours after symptom onset. Studies are currently underway to examine the efficacy of TAMIFLU against potential pandemic strains of influenza.
- Another class of antiviral drugs, the M2 inhibitors amantadine and rimantadine, could potentially be used against pandemic influenza, but resistance to these drugs may develop.
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