Antiviral drugs: ribavirin |
Ribavirin has a broad antiviral spectrum, inhibiting the replication of a wide range of RNA and DNA viruses. It is a nucleoside analogue used in the treatment of chronic hepatitis C in combination with peginterferon alfa or interferon alfa. It has also been used to treat certain haemorrhagic fevers and severe measles infection in immunocompromised patients, and serious lower respiratory tract infection with respiratory syncytial virus (RSV) in hospitalised children.
Haemolytic anaemia is a common adverse effect. Frequent monitoring and dose reduction may be required (particularly in the first 6 weeks). It is contraindicated in patients with haemoglobinopathies or those requiring dialysis. Caution is required in patients with, or suspected of having, ischaemic heart disease. Blood counts must be monitored on a regular basis along with serum electrolytes and creatinine. Skin rashes are occasionally seen early in treatment (10% to 15% of cases), but are usually mild and may not require cessation of therapy.
Ribavirin is embryotoxic or teratogenic, or both, at doses well below the recommended human dose in all animal species studied. It is also genotoxic (mutagenic) and reversibly impairs spermatogenesis. It accumulates intracellularly and its half-life in humans is approximately 12 days. Therefore:
Ribavirin is contraindicated in women who are pregnant or who may become pregnant during exposure.
It is contraindicated in men whose partner is fertile unless both are using effective contraception.
Pregnancy should be avoided until 6 months after completion of therapy.
A man whose partner is already pregnant should use condoms, as it is not known if the concentration in sperm may affect the fetus.
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