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Cephalexin pharmacokinetics in patients with cystic fibrosis
Insights
Cephalexin pharmacokinetics in cystic fibrosis (CF) patients showed variability in renal clearance, but absorption and elimination were generally similar to healthy adults, suggesting dose adjustments may not be needed for mild CF cases.
Area of Science:
- Pharmacology
- Clinical Pharmacy
- Pediatric Pharmacokinetics
Background:
- Cystic Fibrosis (CF) can alter drug pharmacokinetics.
- Understanding cephalexin's behavior in CF patients is crucial for effective treatment.
- Previous studies on cephalexin pharmacokinetics in CF are limited.
Purpose of the Study:
- To investigate the pharmacokinetics of cephalexin in pediatric and adult patients with cystic fibrosis.
- To compare cephalexin's absorption, clearance, and elimination in CF patients versus healthy adults.
- To assess the potential need for dose adjustments in CF patients based on pharmacokinetic parameters.
Main Methods:
- Single-dose administration of cephalexin (250-500 mg) in suspension.
- Pharmacokinetic analysis including area under the curve (AUC), renal clearance, and elimination half-life.
- Comparison of data between pediatric CF patients, adult CF patients, and normal adult volunteers.
Main Results:
- Area under the curve (AUC) normalized for dose and weight was comparable across all groups (pediatric CF, adult CF, healthy adults).
- Significant interindividual variation in cephalexin renal clearance was observed in CF patients.
- Elimination half-life was similar in CF patients and healthy adults.
- High urinary recovery indicated good cephalexin absorption in CF patients.
Conclusions:
- Cephalexin is well absorbed and eliminated similarly in pediatric and adult CF patients compared to healthy adults.
- The observed variability in renal clearance suggests potential individual differences in drug processing.
- Current findings indicate that cephalexin clearance may not significantly increase in CF patients with minimal disease severity and excellent Shwachman scores.
Abstract:
Pharmacokinetics of cephalexin were studied in 7 pediatric and 4 adult patients with cystic fibrosis (CF) and 4 normal adult volunteers. Cephalexin, 250-500 mg, was given as a single dose in suspension. The area under the cephalexin serum concentration-time curve normalized for dose per kilogram averaged 0.185, 0.242, and 0.272 ml/min/kg-1 in pediatric CF patients, adult CF patients, and normal adults, respectively (p greater than 0.05). A threefold interindividual variation was observed in cephalexin renal clearance in CF patients. Renal clearance of cephalexin averaged 5.85 ml/min/kg in pediatric and 4.61 ml/min/kg in adult CF patients (p greater than 0.05). Elimination half-life of cephalexin averaged 0.74, 0.76, and 1.04 h in pediatric patients, adult patients, and normal adults (p greater than 0.05). Cephalexin was well absorbed based on a mean 24-hour urinary recovery of 89 and 93% in pediatric and adult patients. A trend for higher renal clearance of cephalexin was observed among pediatric compared to adult patients. These results indicate that clearance of cephalexin may not increase in patients with CF of minimal severity characterized by an excellent Shwachman score.