Dose reduction for the management of indinavir-related toxicity in human immunodeficiency virus type 1-infected patients in Taiwan: clinical and pharmacokinetic assessment

Sung-Ching Pan¹, Szu-Min Hsieh¹, Chien-Ching Hung^1,2, Pei-Fong Huang¹, Mao-Yuan Chen¹, Shan-Chwen Chang^1
1Department of Internal Medicine, National Taiwan University Hospital, Taipei; and ²Department of Parasitology, National Taiwan University, Taipei, Taiwan

Received: May 17, 2004 Revised: June 21, 2004 Accepted: July 30, 2004

Corresponding author: Dr. Szu-Min Hsieh, Division of Infectious Diseases, Department of Internal Medicine, National Taiwan University Hospital, No. 7 Chung-Shan South Road, , Taiwan. E-mail:

This study evaluated the feasibility of reducing the indinavir (IDV) dosage in Taiwanese patients receiving the standard IDV/ritonavir (RTV) dosage of 800/100 mg twice a day who had undetectable plasma human immunodeficiency virus type 1 (HIV-1) RNA but had developed IDV-related toxicities. After dosage reduction to IDV/RTV 600/100 mg twice a day, the dose-related toxicity decreased and plasma HIV RNA remained undetectable at 24 weeks post-switch in all patients. The maximal plasma concentration (Cmax) and area under the plasma concentration-time curve of IDV decreased significantly (median, 6.3 vs 4.3 g/mL and 1892 vs 1292 g?min/mL, p=0.01 and 0.001, respectively) but the minimal plasma concentration remained at a similar level (median, 1.0 vs 0.8 g/mL, p=0.12). This study found that the reduction in the dosage of IDV in HIV-1 infected patients receiving the standard IDV/RTV regimen guided by therapeutic drug monitoring decreased the Cmax, dose-related toxicity and medical cost without compromising viral control.

Key words: Drug toxicity, human immunodeficiency virus (HIV), indinavir, pharmacokinetics, ritonavir

J Microbiol Immunol Infect 2005;38:31-34.