*Research Department, Infectious Diseases Institute, Makerere University College of Health Sciences, Kampala, Uganda
†Department of Pharmacology and Therapeutics, Trinity College Dublin, Dublin, Ireland
‡Infectious Diseases Network for Treatment and Research in Africa, Kampala, Uganda
§St Stephens Centre, Chelsea and Westminster Hospital, London, United Kingdom
‖Department of Pharmacology and Therapeutics, Makerere University College of Health Sciences, Kampala, Uganda
¶Department of Molecular and Clinical Pharmacology, University of Liverpool, Liverpool, United Kingdom
#Department of GenitoUrinary Medicine, St James's Hospital, Dublin, Ireland.
Correspondence to: Mohammed Lamorde, MBBS, MRCP, Infectious Diseases Institute, PO Box 22418, Kampala, Uganda (e-mail: firstname.lastname@example.org).
This study was funded by the Health Research Board of Ireland.
Presented at the 6th International AIDS Society Conference on HIV Pathogenesis, Treatment and Prevention, July 17–20, 2011, Rome, Italy (MOPE173); and at the 13th European AIDS Conference 2011, Oct 12–14, 2011, Belgrade, Serbia (PE6.6/1).
D. Back and S. Khoo had received travel and research grants from and have been advisers for Janssen, Bristol-Myers Squibb, Merck, Viiv, Gilead, Vertex, and Boehringer Ingelheim.
All other authors have no conflicts of interest to disclose.
Received November 28, 2011
Accepted March 19, 2012
HIV infection disproportionately affects the poorest parts of the world.1 Food insufficiency affects up to one-third of the population in sub-Saharan Africa, where nearly 70% of all HIV infections occur.2,3 Life-long treatment with a combination of antiretroviral drugs is the only therapeutic intervention with proven efficacy against HIV infection.4 Standard management of HIV in adults involves daily administration of a combination of orally administered drugs. However, food intake around the time of drug dosing may alter the bioavailability of orally administered drugs.5 With limited access to food, patients may consume meals less frequently than the prescribed dosing schedule for their medication. Consequently, antiretroviral drugs that can be administered without food are preferred.6
Lopinavir coformulated with ritonavir (LPV/r) is the most widely used HIV protease inhibitor in resource-limited settings. Initially, LPV/r was developed as a soft elastic capsule formulation, which required refrigeration for storage and food intake for optimal absorption.7 The capsule formulation was subsequently replaced by a film-coated tablet, which does not require refrigeration. In manufacturer-initiated studies with single doses of LPV/r, a trend to a reduced food effect was seen with the tablets compared with the capsules. Consequently, the manufacturer recommends that LPV/r tablets can be administered without regard to meals.8,9
However, the effect of food on steady-state pharmacokinetics of lopinavir and ritonavir has not been studied. Furthermore, no formal evaluations have been conducted in African settings using local meals. The present study compared the steady-state pharmacokinetics of lopinavir and ritonavir in Ugandan HIV-infected patients when administered as LPV/r tablets in the fasted state versus administration with a Ugandan moderate fat meal or a Western high fat meal.
Ethics and Regulatory Approval
Ethics committee approval was obtained from the National AIDS Research Committee (ARC 100). The study was approved by the Uganda National Council for Science and Technology (HS 730) and registered on www.pactr.org (PACTR2010030001953121).
This was an open-label, 3-phase, crossover pharmacokinetic study. Enrolled patients were scheduled for intensive pharmacokinetic sampling on 3 occasions 7 days apart (day 1, day 8, and day 15). Assuming a t-distribution of the data, a coefficient of variation of 5% and at an alpha level of ≤0.05, 12 patients were calculated to have 80% probability to detect a 20% difference in the mean area under the concentration–time curve (AUC) of lopinavir between the fasted and either the moderate fat or the high fat meal.
Patients were enrolled if they provided written informed consent, were aged between 18 and 65 years, were stable on a LPV/r-containing antiretroviral regimen for at least 12 months before enrollment (most recent HIV-1 RNA performed over preceding 12 months measuring below 400 copies/mL) and had no recent use of medications (including traditional medicines) known to interfere with cytochrome P450 (CYP) metabolism. Patients were excluded if they were anemic or if they had evidence of derangement in renal function (serum creatinine above 300 μmol/L) or hepatic function (alanine transaminase elevations greater than 5 times the upper limit of normal). Patients were excluded if they had severe intercurrent illnesses, vomiting or diarrhoea, or if they were unable to adhere to the meal sequence prescribed in the study. Pregnant women were excluded from the study.
Patients received LPV/r tablets (Aluvia, Abbott GmbH & Co, KG, Knollstrasse, Germany) twice daily as part of their antiretroviral regimen throughout the study.
On day 1, patients received a moderate fat Ugandan meal (665 Kcal, 20 g fat) comprising local banana (matooke) cooked with onions, tomatoes, and oil and tea without milk. Two adult strength tablets of LPV/r were administered less than 30 minutes after the starting and completing of the meal.
On day 8, LPV/r was administered with a standardized high fat Western breakfast (840 Kcal, 36 g fat) comprising bread, margarine, sausages and tea with milk. On day 15, LPV/r tablets were administered to patients in the fasted state. Patients were advised to withhold food intake for 8 hours before LPV/r dosing and food intake was permitted 4 hours after administration of LPV/r. On each sampling occasion, venous samples were collected predose and 1, 2, 4, 6, 8, 10, and 12 hours post-LPV/r. Plasma samples were obtained by centrifugation at the Makerere University–Johns Hopkins University Laboratory and stored at −70°C until shipment.
Determination of Lopinavir and Ritonavir
Lopinavir and ritonavir concentrations in plasma were determined at the University of Liverpool by a validated high-performance liquid chromatography with tandem mass spectrometry method.10 The lower limit of quantification for lopinavir and ritonavir were 8.3 and 2.5 ng/mL, respectively. For lopinavir and ritonavir, assay accuracy ranged 91.1%–106.7% and 89.5–104.9%, respectively. Coefficient of variation was ≤7.1% for lopinavir and ≤7.6% for ritonavir at all quality control levels.
Adverse events were evaluated using patient questionnaires
Pharmacokinetic parameters including maximal concentrations (Cmax), time to maximal concentration (Tmax), and concentrations 12 hours postdosing (C12) were obtained from the data. Half-life (t1/2) and area under the concentration-time curve (AUC0–12) were calculated by noncompartmental methods (WinNonlin Version 5.2, Pharsight, MountainView, CA). Fasted data (day 15) was used as the reference to facilitate comparison of food effects with results of the manufacturer-initiated single-dose study.8 Geometric means (GM), geometric mean ratios (GMRs) and confidence intervals (CIs) were calculated for the pharmacokinetic parameters of lopinavir and ritonavir. A food effect was assumed if the 90% CI for GMRs between fed and fasted treatments was not contained in the equivalence limits of 80%–125% for either AUC0–12 or Cmax. Statistical comparisons of the derived pharmacokinetic parameters (moderate fat or high fat versus fasted) were performed using the Wilcoxon signed-rank. The P values ≤0.05 were considered statistically significant. Lopinavir C12 was interpreted using a minimum effective concentration of 1000 ng/mL.11
Thirteen patients were enrolled into the study. One patient was discontinued on the first sampling visit due to cannulation difficulties, and no pharmacokinetic data are available. The remaining 12 patients (6 female) completed all phases of the study. The median (interquartile range) age and weight of patients was 48 (44–49) years and 62 (59–68) kg. Eleven patients received zidovudine plus didanosine, whereas 1 patient received tenofovir plus lamivudine. For opportunistic infection prophylaxis, 11 patients used cotrimoxazole and 1 patient was on dapsone.
Lopinavir and ritonavir pharmacokinetic parameters are summarized in Table 1. Lopinavir Tmax (median, interquartile range) was 3 (3–4) hours in the fasted state and 4 (4–6) hours and 4 (4–6) hours with moderate and high fat meals, respectively. Similarly, ritonavir Tmax was 3 (2–4) hours in the fasted state and 4 (4–6) hours and 4 (4–6) hours with moderate and high fat meals, respectively.
Lopinavir AUC0–12 and Cmax were lower by 14% (GMR, 90% CI: 0.86, 0.77–0.95) and 14% (0.86, 0.81–0.92), respectively during administration with a high fat meal compared with the fasted state. Similarly, a 29% significant decrease in ritonavir parameters was observed for AUC0–12 (GMR, 90% CI: 0.71, 0.61–0.84) and Cmax (0.71, 0.60–0.84) with a high fat meal compared to the fasted state. However, compared with the fasted state, administration with a moderate fat meal yielded identical lopinavir and ritonavir AUC0–12 and Cmax results. Figure 1 shows individual curves for Cmax, C12 and AUC0–12 for lopinavir and ritonavir under fasted and high fat meal conditions. Under all meal conditions, lopinavir C12 measured above 1000 ng/mL in all patients.
No adverse events were reported.
Ritonavir exposure parameters (AUC0–12 and Cmax) were 29% lower during administration with a high fat meal. This contrasts with a previously conducted single-dose study in which Klein et al8 found no difference in the pharmacokinetics of ritonavir under fasting, moderate fat, or high fat meal conditions. Similarly, in the present study, lopinavir exposure was significantly reduced by a high fat meal, albeit to a milder degree than ritonavir. In comparison, the single-dose study reported increases of 26% and 19% in lopinavir AUC0–12 with a moderate fat and high fat meal, respectively compared with fasted state.12 The reasons for the contradictory findings between single-dose and steady-state studies are unclear but may relate to the physicochemical characteristics of the tablet formulation and time-dependent metabolism of the study drugs.
In this study, lopinavir and ritonavir peak concentrations were observed to be delayed during LPV/r dosing with food. Slower absorption during coadministration with the moderate fat and high fat meals may have contributed to reduced lopinavir peak/trough deviation and longer lopinavir half-life (as a result of ongoing absorption during the elimination phase). Lopinavir and ritonavir are hydrophobic compounds, which are practically insoluble in water. However, some excipients of the film-coated tablets are hydrophilic and fat could interfere with tablet dissolution and impair the release of the active pharmaceutical ingredients.8 A high fat meal could therefore impair liberation of lopinavir and ritonavir and reduce the bioavailability of these compounds. However, although this explains how fat may reduce drug exposure, it does not explain the absence of a food effect in the prior single-dose study. The fat content of meals used in our study differed from the single-dose study. The moderate fat meal had approximately 30% more fat although the high fat meal had approximately 50% less fat than the corresponding meals used in that study. It is not clear if this could have contributed to the conflicting findings in the 2 studies with regard to LPV/r dosing with a high fat meal.
Lopinavir and ritonavir are metabolized by CYP3A, an enzyme that exhibits time-dependent changes in its activity. Among adults treated with LPV/r, Wyen et al13 reported greater intestinal CYP3A activity at steady state compared with CYP3A activity measured at a single dose of LPV/r. It is therefore possible that enhanced metabolism of lopinavir and/or ritonavir by CYP3A in the intestine at steady state could reveal food effects that were unapparent with a single dose. However, LPV/r induces other drug-metabolizing pathways at steady state, which could also contribute to the study findings.14 Further studies are therefore needed to elucidate the mechanism for the food effect at steady state.
Given that LPV/r is often the only protease inhibitor available in developing countries, it is important that this drug is used optimally. Under all meal conditions studied, lopinavir trough concentrations exceeded the recommended minimum effective concentration for lopinavir and the mild differences under different meal conditions are unlikely to be clinically significant. Extensive evaluations of different meals were impractical so one commonly consumed staple (matooke) was selected, whereas a Western high fat breakfast was used to reflect increasing adoption of Western diets in urban parts of Uganda. Thus, the study meals differed in food type and fat content, and it is possible that food components in 1 meal could have influenced the results independent of the effect of fat.
In conclusion, high fat food intake led to modest reductions in ritonavir and lopinavir exposure compared with the fasted state, but this is not considered to be clinically significant given that lopinavir concentrations at the end of the dosing intervals remained above the target concentration. Consequently, LPV/r tablets can be taken without regard to meals in this population. However, given that lopinavir and ritonavir pharmacokinetic parameters (AUC and Cmax) were reduced by a high fat meal, a finding not seen in the previously conducted single-dose study, consideration should be given to the optimal design of food effect studies.
The authors thank the study patients and members of the clinical study team (D. Ekusai, J. Nakku, H. Tibakabikoba and J. Magoola). We acknowledge staffing and logistics support from the Infectious Diseases Network for Treatment and Research in Africa (INTERACT), the European and Developing Countries Clinical Trials Partnership, the Haughton Institute, Dublin Ireland, and the Sewankambo Scholarship Program funded by Gilead Foundation at IDI.
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