Comparison of Oral and Aerosol Ribavirin Regimens in the High Risk Elderly

A comparison of different regimens of ribavirin (R), administered either orally or by aerosol, was performed in 16 elderly subjects (13 men, 3 women, mean age 63 ± 8 years) considered to be in the “high‐risk” category for complications from influenza as defined by the Centers for Disease Control. The subjects were divided into four groups. Group O‐600 received 600 mg orally R every 8 hours for 48 hours followed by 200 mg every 8 hours for 72 hours for a total dose of 5.4 g (22.1 mmol). Group O‐800 received 800 mg oral R every 8 hours for 24 hours followed by 400 mg every 12 hours for 96 hours for a total dose of 4.1 g (22.9 mMoles). Group A‐40 received R (40 mg/ml) aerosolized through a small particle aerosol generator for 6 hours every 12 hours for 96 hours, yielding an average delivered dose of 6.2 g (25.4 mMoles) R. Group A‐60 received aerosolized R (60 mg/mL) for 2 hours every 8 hours for 96 hours, yielding an average delivered dose of 4.6 g (18.8 mMoles) R. No hematologic or other laboratory abnormalities were associated with any of the regimens. Group O‐800 and O‐600 reached mean peak plasma R levels of 11.8 μM and 5.3 μM, respectively, after 18 hours of therapy. Subsequent administration of 20 mg R every 8 hours was sufficient to maintain a plasma R level greater than 7 μM. Among the aerosol groups, group A‐40 approached steady state plasma R levels (8–10 μM) more quickly than group A‐60. Steady state levels could be maintained by administering 60 mg/ml aerosol R for 2 hours, every 8 hours. No adverse pulmonary effects were noted in any patient. Further trials evaluating the clinical efficacy of oral and aerosol ribavirin in the elderly should be carried out.