Rhabdomyolysis in an HIV-infected patient with impaired renal function concomitantly treated with rosuvastatin and lopinavir/ritonavir.

The authors describe an HIV-infected patient with moderate renal failure receiving combination antiretroviral therapy. Because of dyslipidaemia he was initially treated with pravastatin but developed rhabdomyolysis after a switch to rosuvastatin. With this case we illustrate that statins as well as antiretroviral therapy are susceptible to clinical relevant drug-drug or drug-disease interactions. Knowledge of these interactions is important to provide patients with the best possible care.

Pharmacokinetics of lopinavir in HIV type-1-infected children taking the new tablet formulation once daily.

BACKGROUND: Recently, a new tablet formulation of the widely used HIV protease inhibitor lopinavir/ritonavir was licensed. Here, we present a pilot study of the pharmacokinetics of the new adult tablet formulation taken once daily in children. METHODS: Lopinavir pharmacokinetics of the new adult tablet formulation were evaluated in 15 HIV type-1-infected children between 4 and 15 years of age. A target dose of 460/115 mg/m2 was administered once daily. Plasma concentrations of lopinavir over the course of 24 h were determined with a validated HPLC method. RESULTS: The median lopinavir dose was 498 mg/m2 (range 424-548). The mean +/- SD for lopinavir area under the 24 h curve was 217.9 +/- 44.9 mg/l x h, the maximum concentration was 14.8 +/- 2.4 mg/l and the concentration 24 h after intake was 3.1 +/- 2.6 mg/l. The half-life of lopinavir was 5.8 +/- 4.5 h and the median time to maximum concentration was 5.8 h (range 1.8-12.2). Overall, the tablet formulation resulted in greater exposure to lopinavir with less variability compared with the soft-gel capsule formulation. All children treated with the new adult tablet formulation had undetectable viral loads (< 50 copies/ml) during 24 weeks follow-up. CONCLUSIONS: The tablet formulation could probably result in improved lopinavir dosing and increases the feasibility of once-daily lopinavir/ritonavir-based regimens in children.

Pharmacokinetics and pharmacodynamics of combined use of lopinavir/ritonavir and rosuvastatin in HIV-infected patients.

BACKGROUND: Lopinavir/ritonavir-containing antiretroviral therapy can cause hyperlipidaemia. However, most statins are contraindicated due to drug-drug interactions. Rosuvastatin undergoes minimal metabolism by CYP450, so no CYP450-based interaction with lopinavir/ritonavir is expected. This study explored the lipid-lowering effect of rosuvastatin and assessed the effect of lopinavir/ritonavir on the pharmacokinetics of rosuvastatin and vice versa. METHODS: HIV-infected patients on lopinavir/ritonavir (viral load < 400 copies/ml) with total cholesterol (TC) > 6.2 mmol/l were treated with rosuvastatin for 12 weeks, starting on 10 mg once daily. If fasting target values (TC < 5.0 mmol/l, high-density lipoprotein-cholesterol > 1.0 mmol/l, low-density lipoprotein-cholesterol [LDL-c] < 2.6 mmol/l and triglycerides < 2.0 mmol/l) were not reached, rosuvastatin was escalated to 20 mg or 40 mg at week 4 and 8, respectively. Plasma lopinavir/ritonavir trough levels (C(min)) were determined at week 0, 4, 8 and 12 and rosuvastatin C(min), at week 4, 8 and 12. RESULTS: Twenty-two patients completed the study. Mean reductions in TC and LDL-c from baseline to week 4 (on rosuvastatin 10 mg once a day) were 27.6% and 31.8%, respectively. Lopinavir/ritonavir concentrations were not influenced by rosuvastatin (P = 0.44 and 0.26, repeated-measures analysis). Median (interquartile range) rosuvastatin C(min) for 10 mg, 20 mg and 40 mg once daily were 0.97 (0.70-1.5), 2.5 (1.3-3.3) and 5.5 (3.3-8.8) ng/ml, respectively. CONCLUSIONS: Rosuvastatin appeared to be an effective statin in hyperlipidaemic HIV-infected patients. Lopinavir/ritonavir levels were not affected by rosuvastatin, but rosuvastatin levels unexpectedly appeared to be increased 1.6-fold compared with data from healthy volunteers. Until safety and efficacy have been confirmed in larger studies, the combination of rosuvastatin and lopinavir/ritonavir should be used with caution.

Interaction study of the combined use of paroxetine and fosamprenavir-ritonavir in healthy subjects.

Human immunodeficiency virus-infected patients have an increased risk for depression. Despite the high potential for drug-drug interactions, limited data on the combined use of antidepressants and antiretrovirals are available. Theoretically, ritonavir-boosted protease inhibitors may inhibit CYP2D6-mediated metabolism of paroxetine. We wanted to determine the effect of fosamprenavir-ritonavir on paroxetine pharmacokinetics and vice versa and to evaluate the safety of the combination. Group A started with 20 mg paroxetine every day for 10 days; after a wash-out period of 16 days, subjects received paroxetine (20 mg every day) plus fosamprenavir-ritonavir (700/100 mg twice a day) from days 28 to 37. Group B received the regimens in reverse order. On days 10 and 37, pharmacokinetic curves were recorded. Twenty-six healthy subjects (18 females, 8 males) were included. Median (range) age and weight were 44.4 (18.2 to 64.3) years and 68.8 (51.0 to 89.4) kg. Three subjects were excluded (two because of adverse events; one for nonadherence). Addition of fosamprenavir-ritonavir to paroxetine resulted in a significant decrease in paroxetine exposure: the geometric mean ratios (90% confidence intervals) of paroxetine plus fosamprenavir-ritonavir to paroxetine alone were 0.45 (0.41 to 0.49) for the area under the concentration-time curve from 0 to 24 h (AUC(0-24)), 0.49 (0.45 to 0.53) for the maximum concentration of the drug in plasma (C(max)), and 0.75 (0.71 to 0.80) for the apparent elimination half-life (t(1/2)). The free fraction of paroxetine showed a median (interquartile range) increase of 30% (18 to 42%) after the addition of fosamprenavir-ritonavir. The AUC(0-12), C(max), C(min), and t(1/2) of amprenavir and ritonavir were similar to those of historical controls. No serious adverse events occurred. Fosamprenavir-ritonavir reduced total paroxetine exposure by 55%. This is partly explained by protein displacement of paroxetine. We think that this interaction is clinically relevant and that titration to a higher dose of paroxetine may be necessary to accomplish the needed antidepressant effect.

Lopinavir/ritonavir reduces lamotrigine plasma concentrations in healthy subjects.

BACKGROUND: Limited data are available about the effect of lopinavir and low-dose ritonavir on glucuronidation. Lamotrigine undergoes glucuronidation. We studied the effect of lopinavir/ritonavir on the pharmacokinetics of lamotrigine and vice versa. METHODS: Twenty-four healthy subjects received 50 mg lamotrigine once daily on days 1 and 2 and 100 mg twice daily on day 3 through day 23. Lopinavir (400 mg twice daily)/ritonavir (100 mg twice daily) was added on day 11. Depending on the decrease in lamotrigine trough level between days 10 and 20, either the study was stopped (<20% decrease) or a dose increase was applied from day 23 to day 31, as follows: increase to 150 mg lamotrigine twice daily if there was a 20% to 33% decrease, increase to 200 mg twice daily if there was a 34% to 66% decrease, and increase to 300 mg twice daily if there was a greater than 66% decrease. On days 10, 20, and 31, 12-hour pharmacokinetic curves were drawn. RESULTS: The mean decrease in lamotrigine trough level between days 10 and 20 was 55.4% (n = 18). A dose increment to 200 mg lamotrigine twice daily was used in all subjects. The area under the plasma concentration-time curve (AUC) values of lamotrigine on day 20 (with lopinavir/ritonavir) and day 10 (without lopinavir/ritonavir) were bioinequivalent, with a point estimate of 0.50 (90% confidence interval, 0.47-0.54). After dose adjustment of lamotrigine to 200 mg twice daily, the AUC on day 31 (n = 15) was bioequivalent to that on day 10, with a point estimate of 0.91 (90% confidence interval, 0.82-1.02). The median AUC ratios of lamotrigine 2N-glucuronide to lamotrigine on day 10 and day 20 were 0.57 (interquartile range, 0.39-0.75) and 1.12 (interquartile range, 0.87-1.31). Pharmacokinetic parameters for lopinavir/ritonavir were similar to historical controls. CONCLUSION: Lopinavir/ritonavir decreases the AUC of lamotrigine, probably by induction of glucuronidation. A dose increment to 200% of the initial lamotrigine dose is needed to achieve concentrations similar to those with lamotrigine alone. Lamotrigine does not appear to affect the pharmacokinetics of lopinavir/ritonavir.

Pharmacokinetics of a once-daily regimen of lopinavir/ritonavir in HIV-1-infected children.

INTRODUCTION: Lopinavir is an HIV protease inhibitor that is co-formulated with ritonavir. The approved paediatric dose is 230/57.5 mg/m2 twice daily. Once-daily dosing may offer an advantage to adherence. We studied the pharmacokinetics of lopinavir/ritonavir in a once-daily regimen in HIV-1-infected children. METHODS: HIV-1-infected children on stable antiretroviral therapy with a viral load <50 copies/ml for at least 6 months received lopinavir/ritonavir 460/115mg/m2 once daily with zidovudine and lamivudine. Blood samples were collected at 0, 2, 4, 6, 8, 12, 18 and 24 h after observed intake during steady state. Target level for lopinavir Cmin was 1.0 mg/l, based on in vitro IC50 data. RESULTS: Nineteen HIV-1-infected children with a median (range) age of 4.5 (1.4-12.9) years were enrolled. The median (interquartile range) dose of lopinavir was 456 (444-477) mg/m2. The mean (standard deviation) AUC0-24, Cmax and Cmin of lopinavir were 149.8 +/- 58.8 h*mg/l, 10.77 +/- 2.90 mg/l and 2.88 +/- 3.74 mg/l respectively. These values are comparable to data observed in adults using lopinavir/ritonavir 800/200 mg once daily. In 10/19 (53%) children Cmin was considered to be too low (<1.0 mg/l). Younger children more often experienced subtherapeutic trough levels. CONCLUSION: Our findings indicate that 460/115 mg/m2 lopinavir/ritonavir once daily leads to mean pharmacokinetic parameters comparable to data of 800/200 mg lopinavir/ritonavir once daily in adults, although the variability observed in the trough levels is much higher in children. Further research, especially in young children, is necessary to determine whether a higher dosage of lopinavir/ritonavir once daily must be given to reach the target level for Cmin.

The genotypic inhibitory quotient and the (cumulative) number of mutations predict the response to lopinavir therapy.

For 95 protease inhibitor-experienced HIV-1-infected patients, the genotypic inhibitory quotient (GIQ; trough level/number of mutations) was calculated for lopinavir. Three different sets of mutations showed equal predictive value. However, the use of cumulative numbers of mutations for calculation of the GIQ showed significantly better association with the virological response. Furthermore, the predictive value of the GIQ was no different from that of the number of mutations alone.