The letter of Spray et al.1 about dosage adjustments for hepatic dysfunction provides useful recommendations. The information presented, however, was exclusively from package inserts from medications that received marketing approval from FDA through November 2005. We believe that this kind of information should be obtained using a more comprehensive search and should at least include recommendations available in important guidelines, such as those for treating HIV infection,2 and other prescribing information.3,4 These sources provide more accurate information on dosage adjustments according to the hepatic dysfunction classification. Using such sources, we found some information that differs or is missing from that presented by Spray et al. on dosage recommendations for abacavir, amprenavir, fosamprenavir, and vardenafil. We also believe that the information of Spray et al. on voriconazole is confusing and should be clarified. In addition, we identified some drugs that were not included by Spray et al.: tipranavir, parecoxib, lumiracoxib, and eplerenone.