Pharmacokinetics of rifampin and clarithromycin in patients treated for Mycobacterium ulcerans infection.

In a randomized controlled trial in Ghana, treatment of Mycobacterium ulcerans infection with streptomycin (SM)-rifampin (RIF) for 8 weeks was compared with treatment with SM-RIF for 4 weeks followed by treatment with RIF-clarithromycin (CLA) for 4 weeks. The extent of the interaction of RIF and CLA combined on the pharmacokinetics of the two compounds is unknown in this population and was therefore studied in a subset of patients. Patients received CLA at a dose of 7.5 mg/kg of body weight once daily, rounded to the nearest 125 mg. RIF was administered at a dose of 10 mg/kg, rounded to the nearest 150 mg. SM was given at a dose of 15 mg/kg once daily as an intramuscular injection. Plasma samples were drawn at steady state and analyzed by liquid chromatography-tandem mass spectroscopy. Pharmacokinetic parameters were calculated with the MW/Pharm (version 3.60) program. Comedication with CLA resulted in a 60% statistically nonsignificant increase in the area under the plasma concentration-time curve (AUC) for RIF of 25.8 mg x h/liter (interquartile ratio [IQR], 21.7 to 31.5 mg x h/liter), whereas the AUC of RIF was 15.2 mg x h/liter (IQR, 15.0 to 17.5 mg x h/liter) in patients comedicated with SM (P = 0.09). The median AUCs of CLA and 14-hydroxyclarithromycin (14OH-CLA) were 2.9 mg x h/liter (IQR, 1.5 to 3.8 mg x h/liter) and 8.0 mg x h/liter (IQR, 6.7 to 8.6 mg x h/liter), respectively. The median concentration of CLA was above the MIC of M. ulcerans, but that of 14OH-CLA was not. In further clinical studies, a dose of CLA of 7.5 mg/kg twice daily should be used (or with an extended-release formulation, 15 mg/kg should be used) to ensure higher levels of exposure to CLA and an increase in the time above the MIC compared to those achieved with the currently used dose of 7.5 mg/kg once daily.

Comparison of clarithromycin and ciprofloxacin therapy for Bacillus anthracis Sterne infection in mice with or without (60)Co gamma-photon irradiation.

Biological agents and ionizing radiation lead to more severe clinical outcomes than either insult alone. This study investigated the survival of non-irradiated and (60)Co-gamma-irradiated mice given therapy for inhalation anthrax with ciprofloxacin (CIP) or a clinically relevant mixture of clarithromycin (CLR) and its major human microbiologically important metabolite 14-hydroxy clarithromycin (14-OH CLR). All B6D2F1/J 10-week-old female mice were inoculated intratracheally with 3 x 10(8) c.f.u. of Bacillus anthracis Sterne spores 4 days after the non-lethal 7 Gy dose of (60)Co gamma radiation. Twenty-one days of treatment with CLR/14-OH CLR, 150 mg kg(-1) twice daily, or CIP, 16.5 mg kg(-1) twice daily, began 24 h after inoculation. Pharmacokinetics indicate that the area under the curve (AUC) for 14-OH CLR on the concentration-versus-time graph was slightly higher in gamma-irradiated than non-irradiated animals. Neither drug was able to increase survival in gamma-irradiated animals. CIP and CLR/14-OH CLR therapies in non-irradiated animals increased survival from 49 % (17/35 mice) in buffer-treated animals to 94 % (33/35) and 100 %, respectively (P < 0.001). B. anthracis Sterne only was isolated from 25-50 % of treated mice with or without irradiation. Mixed infections with B. anthracis Sterne were present in 50-71 % of gamma-irradiated mice but only in 5-10 % of mice without irradiation.

Gastric juice, gastric tissue and blood antibiotic concentrations following omeprazole, amoxicillin and clarithromycin triple therapy.

BACKGROUND: Amoxicillin and clarithromycin are key antibiotics in proton pump inhibitor-based Helicobacter pylori eradication therapies. AIMS: To study gastric mucus and tissue concentrations and collect basic data about optimal antibacterial doses. METHODS: Plasma, gastric mucosa and gastric juice antibiotic concentrations were measured following either low- or high-dose amoxicillin (750 or 1000 mg b.i.d.) and clarithromycin (400 or 500 mg b.i.d.) given in combination with omeprazole 20 mg bid to 12 male volunteers in an open crossover design. Gastric juice and mucosal biopsy collection was performed either 2 (n=6) or 6 hours (n=6) after dosing. RESULTS: Amoxicillin concentrations 2 hours after high dosage were gastric juice > gastric body > antral mucosa > plasma. At 6 hours, plasma and gastric juice concentrations were still above the MIC for amoxicillin-susceptible bacteria but no antibiotic was detectable in mucosa samples. Clarithromycin concentrations after high dosage were gastric juice > mucosa > serum; all above the MIC for clarithromycin-susceptible bacteria at both 2 and 6 hours. CONCLUSIONS: Both dosage regimens provided effective antibiotic concentrations in gastric juice at 2 hours. After dosing, both antibiotics demonstrated high gastric tissue concentrations via local diffusion while clarithromycin also provided sustained delivery (6 hours) via gastric mucosa penetration.

Effects of cysteine on the pharmacokinetics of intravenous clarithromycin in rats with protein-calorie malnutrition.

Effects of cysteine on the pharmacokinetics of clarithromycin were investigated after intravenous administration of the drug at a dose of 20 mg/kg to control rats (4-week fed on 23% casein diet) and rats with PCM (protein-calorie malnutrition, 4-week fed on 5% casein diet) and PCMC (PCM treated with 250 mg/kg for oral cysteine twice daily during the fourth week). Clarithromycin has been reported to be metabolized via hepatic microsomal cytochrome P450 (CYP) 3A4 to 14-hydroxyclarithromycin (primary metabolite of clarithromycin) in human subjects. It has also been reported that in rats with PCM, CYP3A23 level decreased to 40-50% of control level, but decreased CYP3A23 level in rats with PCM completely returned to control level by oral cysteine supplementation (rats with PCMC). Human CYP3A4 and rat CYP3A23 proteins have 73% homology. In rats with PCM, the area under the plasma concentration-time curve from time zero to time infinity, AUC (567, 853 and 558 microg min/ml for control rats and rats with PCM and PCMC, respectively) and percentage of clarithromycin remaining after incubation with liver homogenate (69.6, 83.9 and 71.7%) were significantly greater than those in control rats and rats with PCMC. Moreover, in rats with PCM, the total body clearance, CL (35.3, 23.4 and 35.8 ml/min/kg), nonrenal clearance, CL(NR) (21.3, 15.2 and 24.1 ml/min/kg) and maximum velocity for the disappearance of clarithromycin after incubation with hepatic microsomal fraction, V(max) (351, 211 and 372 pmol/min/mg protein) were significantly slower than those in control rats and rats with PCMC. However, above mentioned each parameter was not significantly different between control rats and rats with PCMC. The above data suggested that metabolism of clarithromycin decreased significantly in rats with PCM as compared to control due to significantly decreased level of CYP3A23 in the rats. By cysteine supplementation (rats with PCMC), some pharmacokinetic parameters of clarithromycin (AUC, CL, CL(NR) and V(max)) were restored fully to control levels because CYP3A23 level was completely returned to control level in rats with PCMC.

Efficacy of clarithromycin for treatment of experimental Lyme disease in vivo.

Clarithromycin provided effective therapy against arthritis induced by Borrelia burgdorferi infection in the hamster. In vitro, clarithromycin was at least 1 log more potent than tetracycline against two isolates of B. burgdorferi from human sources, as measured by MICs and 50% inhibitory concentrations. Clarithromycin was effective in preventing the onset of B. burgdorferi-induced arthritis, as determined by several parameters of paw swelling. When administered after the onset of arthritis, clarithromycin therapy reduced the degree of swelling and decreased recovery time. These results suggest that clarithromycin has potential as an effective therapy for Lyme disease.