Pharmacokinetics and pharmacodynamics of nelfinavir administered twice or thrice daily to human immunodeficiency virus type 1-infected children

We studied the pharmacokinetics and pharmacodynamics of nelfinavir administered 2 or 3 times per day to human immunodeficiency virus type 1 (HIV-1)-infected children receiving highly active antiretroviral therapy containing nelfinavir. The geometric mean trough concentrations of nelfinavir for the thrice- and twice-daily regimens were 1.55 mg/L and 1.11 mg/L, respectively (P=not significant). Nelfinavir concentrations did not correlate with total daily dose, dose per kilogram of weight, age, weight, previous protease inhibitor (PI) experience, or CD4(+) cell percentage. In the 25 PI-naive children, the virus load reductions at 24 weeks of treatment with the twice- and thrice-daily regimens were comparable. A significantly higher percentage of children in the twice-daily group had a trough concentration of nelfinavir of less than the inhibitory concentration of 95% (P=.042). The decrease in the virus load at 24 weeks of treatment was not correlated with the trough concentration of nelfinavir. The variability of trough concentrations was extremely high, particularly among recipients of the twice-daily regimen, resulting in a higher number of patients with subinhibitory concentrations of nelfinavir in this group.

Specific high-performance liquid chromatography assay for determination of rifabutin plasma concentration following Extrelut column extraction

A specific, precise and accurate assay for determination of rifabutin in human plasma using Extrelut column extraction was developed and validated. Rifabutin concentrations were calculated with a standard curve ranging from 5 to 800 ng ml(-1). using a split-curve approach. Chromatographic peaks were separated by means of a 5 microm Symmetry Shield RP8 using a KH2PO4 (0.05 M) buffer-acetonitrile mobile phase. Detection wavelength was set at 275 nm. Chromatography was carried out at room temperature (20-25 degrees C). The limit of quantification was 5 ng ml(-1). The recovery was over 71%. The intra-day precision of the assay was 5, 7, and 1% while the inter-day precision was 11.2, 8.1, and 5.8% at concentrations of 30, 150 and 500 ng ml(-1), respectively. The accuracy ranged from 99 to 108%. Forty of the drugs most commonly administered to HIV-positive patients were found not to interfere with the assay. The assay has been used in a comparative study of rifabutin pharmacokinetics in HIV-positive patients with or without wasting syndrome. reserved.

Penetration of dapsone into pulmonary lining fluid of human immunodeficiency virus type 1-infected patients

We studied the penetration of dapsone into the epithelial lining fluid (ELF) of sixteen human immunodeficiency virus type 1-infected patients who had received the drug at a dose of 100 mg twice weekly as primary prophylaxis for Pneumocystis carinii pneumonia. Bronchoscopy, bronchoalveolar lavage (BAL), and venipuncture were performed for each patient at a specific time after administration of the last dose of dapsone. Dapsone concentrations in plasma and BAL were determined by high-performance liquid chromatography. The apparent volume of ELF recovered by BAL was determined by using urea as an endogenous marker. The mean concentrations of dapsone in ELF at 2 h (five patients), 4 h (three patients), 12 h (two patients), 24 h (three patients), and 48 h (three patients) were 0.95, 0.70, 1.55, 0.23, and 0.45 mg/liter, respectively, while concentrations in plasma were 1.23, 0.79, 1.31, 0.83, and 0.18 mg/liter, respectively. Dapsone concentrations in ELF were 76, 79, 115, 65, and 291% of those observed in plasma at the same times, respectively. These data show that dapsone is well distributed into ELF and that a twice-weekly 100-mg prophylactic regimen results in sustained concentrations in this compartment.

High-dose fluconazole therapy for cryptococcal meningitis in patients with AIDS

Fluconazole (800-1,000 mg i.v.) was administered to 14 consecutive patients with AIDS and cryptococcal meningitis. At 10 weeks the rate of clinical success was 54.5% (six of 11 patients responded to fluconazole); the Kaplan-Meier estimate of the response rate was 67.1%, and the overall mortality rate was 18.2% (two of 11 patients died). At the end of treatment, eight (72.7%) of 11 patients responded to fluconazole. The median time to the first negative cerebrospinal fluid (CSF) culture was 33.5 days (95% confidence interval, 18.3-67.3); the median time for patients with initial CSF cryptococcal antigen titers of > or = 1:1,024 was 66 days compared with 18 days for patients with initial CSF cryptococcal antigen titers of < 1:1,024 (P = .06). The median time to the first negative CSF culture for patients with an isolate for which the minimum inhibitory concentration (MIC) was 4 micrograms/mL was 56 days compared with 16 days for patients with an isolate for which the MIC was < 4 micrograms/mL (P = .11). The mean serum and CSF levels of fluconazole at steady state were 42.47 +/- 26.31 micrograms/mL and 36.63 +/- 21.08 micrograms/mL, respectively (ratio of CSF:serum, 0.86). No treatment was interrupted and no dose was tapered because of side effects. High-dose fluconazole might be an effective and well-tolerated therapeutic option for patients with AIDS and acute cryptococcal meningitis.

Pharmacokinetics of dapsone in human immunodeficiency virus-infected children

Dapsone, administered at various doses and schedules, has been proven to be a safe and effective alternative to trimethoprim-sulfamethoxazole for prevention of Pneumocystis carinii pneumonia (PCP) in adults with human immunodeficiency virus (HIV) infection. Dapsone is also recommended by the Centers for Disease Control for PCP prophylaxis in HIV-infected children. However, the suggested dosage regimen is based upon clinical experience with children with leprosy and dermatitis herpetiformis rather than pharmacokinetic and pharmacodynamic data obtained from the target patient population. In order to determine a rational dosage regimen that could be tested in clinical studies aimed at the evaluation of dapsone for the prevention of PCP in HIV-infected children, we studied the pharmacokinetics of dapsone following a 2-mg/kg of body weight oral dose in twelve HIV-positive children aged 9 months to 9 years. Plasma was collected at the following times after dapsone administration: 0, 2, 4, 6, 12, 24, 48, 72, and 96 h. The levels of dapsone in plasma were determined by high-performance liquid chromatography. Data were analyzed by noncompartmental methods. Expressed as means +/- standard deviations (ranges), the pharmacokinetic parameters were as follows: peak concentration in plasma, 1.12 +/- 0.48 (0.44 to 1.81) mg/liter; time to peak concentration in plasma, 3.8 +/- 1.3 (2 to 6) h; half-life at elimination phase, 24.2 +/- 7.1 (14.4 to 35.0) h; clearance from plasma divided by bioavailability (CL/F), 1.15 +/- 0.67 (0.37 to 2.63) ml/min/kg; and volume of distribution divided by bioavailability (V/F), 2.25 +/- 1.20 (1.00 to 4.57) liters/kg. Oral CL correlated negatively with age (r = 0.614 and P = 0.034), as did V (r = 0.631 and P = 0.028). As a consequence of the high interindividual variability in growth retardation, pharmacokinetic parameters correlated with measures of body development better than they did with age (e.g., for CL/F to height, r = 0.765 and P = 0.004, and for V/F to height, r = 0.748 and P = 0.005). Since oral CL from plasma and V were positively and highly correlated (r = 0.898 and P = 0.0001), a lower absolute F may be the cause, in part, of higher values for CL/F and V/F in smaller children. The results of this study warrant the testing of a 2-mg/kg dose of dapsone administered twice or thrice weekly to HIV-infected children. The monitoring of drug levels in plasma and dosage adjustment may be necessary for smaller children.

The prevalence of rubella infection in Somalia

A serological survey was carried out to determine the rubella antibodies among Somalian population with an enzyme-linked immunosorbent assay (ELISA). The prevalence of rubella infection in Somalia was found to be 65.6%. Rubella immunity rises with increasing age of subjects from the second year of life.