Effect of Altitude (2500 M) on The Pharmacokinetics of Diclofenac Sodium and Cefadroxil After Oral Administration To Human Volunteers

Abstract

This paper reports, for the first time, the data on the pharmacokinetic characteristics of diclofenac sodium and cefadroxil at Albaha, 2500 M altitude (ALT) , KSA. Therefore, the objective of this study was to compare the plasma concentrations and pharmacokinetic parameters of diclofenac sodium (Voltaren  50 tablets, Ciba Geigy, USA) and cefadroxil (Ultrcef  500 capsules, Bristol L. Germany) at altitude of 2500 M (ALT) and at sea level (SEA) after oral administration to 12 healthy volunteers. A two-way cross over study design was used to compare pharmacokinetic parameters at ALT and SEA. Following drug administration, blood withdrawn into heparinized test tubes over a period of 12 hours. Drug concentrations were determined in the withdrawn samples by fully validated and optimized HPLC methods for the two drugs. The pharmacokinetic parameters including C max , t max , t 0.5e , t 0.5a , K e , K a , V d , Cl T , AUC 0-12h , and AUC 0-∞ were determined by a computer programs. Statistical analysis of the obtained plasma drug concentrations and pharmacokinetic parameters were performed using ANOVA computerized system. Results obtained showed significant differences in the plasma concentrations and all pharmacokinetic parameters of the two drugs at ALT as compared to SEA. There was a significant increase in C max and AUC 0-12h , of both drugs at ALT as compared to SEA. The values of Vd and Cl T were significantly lower at ALT than SEA. ALT could markedly inhibit the metabolism and renal excretion of both drugs as indicated by significant increase in the elimination half-lives (t 0.5e ) and decrease in the elimination rate constant (K e ) at ALT as compared to SEA. The obtained results clearly indicate that the plasma concentrations and all the pharmacokinetic parameters of both diclofenac sodium and cefadroxil are significantly modified by ALT. Therefore, dosage regiemens adjustment is important when diclofenac sodium and cefadroxil are prescribed for administration at ALT to maintain drug efficacy and safety and to avoid drug , s toxicity.