A retrospective, cohort-based survey of patients using twice-daily indinavir + ritonavir combinations: pharmacokinetics, safety, and efficacy.
OBJECTIVE
To describe the pharmacokinetics, safety, and efficacy of twice-daily indinavir + ritonavir regimens


METHODS
A cohort-based survey of HIV-infected patients who either used indinavir 800 mg + ritonavir 100 mg twice daily or indinavir 400 mg + ritonavir 400 mg twice daily.


METHODS
Data were extracted from a database of samples sent to our laboratory for measurement of indinavir + ritonavir plasma concentrations. Patient characteristics, safety, and efficacy measurements were collected by retrospective chart review.


RESULTS
100 Patients using 800-mg indinavir + 100-mg ritonavir twice daily and 32 patients using 400-mg indinavir + 400-mg ritonavir twice daily were eligible. Median peak and trough concentrations of indinavir were 6.8 and 0.77 mg/L in the 800/100 group and 2.6 and 0.45 mg/L in the 400/400 group. The most frequently found side effects were nausea and vomiting, which occurred in 22.1% and 34.9% of the patients in the 800/100 and the 400/400 groups, respectively. Viral load data were analyzed for patients who switched from 800-mg indinavir three times daily to one of the indinavir + ritonavir twice daily regimens. At the time of switch 63% (800/100 group) and 60% (400/400 group) had an undetectable viral load and this increased to 77% and 70%, respectively, during follow-up. Patients who switched to the 400/400 group discontinued treatment more frequently than patients who switched to the 800/100 group (70% vs. 26%, p =.008).


CONCLUSIONS
Indinavir + ritonavir regimens show improved pharmacokinetic properties, allowing twice-daily dosing with food. Clinical data suggest that safety and efficacy is at least as good as with indinavir three-times-daily regimens without ritonavir. Prospective, comparative trials are needed to properly assess the role in HIV therapy of these twice-daily indinavir + ritonavir regimens.
Department of Clinical Pharmacy, University Medical Centre Nijmegen, The Netherlands. D.Burger@klinfarm.azn.nl
D M
DM
Burger
P W
PW
Hugen
R E
RE
Aarnoutse
J P
JP
Dieleman
J M
JM
Prins
T
T
van der Poll
J H
JH
ten Veen
J W
JW
Mulder
P L
PL
Meenhorst
W L
WL
Blok
J T
JT
van der Meer
P
P
Reiss
J M
JM
Lange
D015331:Cohort Studies; D004359:Drug Therapy, Combination; D015658:HIV Infections / Q000188:drug therapy* / Q000821:virology; D017320:HIV Protease Inhibitors / Q000493:pharmacokinetics / Q000627:therapeutic use*; D015497:HIV-1 / Q000502:physiology; D006801:Humans; D019469:Indinavir / Q000493:pharmacokinetics / Q000627:therapeutic use*; D012189:Retrospective Studies; D019438:Ritonavir / Q000493:pharmacokinetics / Q000627:therapeutic use*; D016896:Treatment Outcome; D019562:Viral Load
D017320:HIV Protease Inhibitors; D019469:Indinavir; D019438:Ritonavir