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The Influence of Khat on the In-Vitro and In-Vivo Availability of Tetracycline-HCl


Affiliations
1 Department of Pharmaceutics, College of Pharmacy and Health Sciences, Ajman University of Science and Technology, United Arab Emirates
2 Department of Pharmaceutical Chemistry, College of Pharmacy and Health Sciences, Ajman University of Science and Technology, United Arab Emirates
     

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The influence of khat on both in-vitro and in-vivo availability of tetracycline-HCl has been evaluated. The in-vitro availability data have reflected a statistically significant interaction between khat extract and tetracycline-HCl in two buffer solutions simulating intestinal and gastric media (phosphate buffer-pH 7 and 0.1 HCl-pH 1.2 respectively). In the in-vivo availability studies, ten adult healthy Yemeni volunteers participated. The obtained in-vivo availability data indicated a statistically significant reduction in most pharmacokinetics parameters. A statistically significant % reduction in the maximum plasma tetracycline-HCl concentration (Cmax) and absorption rate constant (Ka) as well as a significant enhancement of time to reach the peak plasma concentration (Tmax), were observed as a result of taking tetracycline-HCl just before khat chewing (trial B) and more pronounce during khat chewing (trial D) compared to the control (trial C). In addition a statistically significant % reduction in area under curve (AUC0→∞) has been observed reflecting a reduction in the extent of in-vivo tetracycline-HCl availability as a result of khat chewing. Statistically significant % reductions in the biologic half-life (t½) and elimination rate constant (Kel) were also observed.The reduction in tetracycline-HCl concentration when mixed with khat extract, as shown by in-vitro data, may reflect a possible formation of tetracycline-HCl complexes with one or more of khat constituents. The reduction in the rate and extent of in-vivo tetracycline-HCl availability as a result of khat chewing, may be due to the possible formation of non-absorbable tetracycline-HCl complexes with one or more of khat constituents or possible delaying of gastric emptying induced by khat that may prolong the resident time of tetracycline-HCl in the stomach leading to its possible degradation into the less antimicrobial active form epitetracycline.

Keywords

Availability, Pharmacokinetics Parameters, Tetracycline-HCl, Khat.
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  • The Influence of Khat on the In-Vitro and In-Vivo Availability of Tetracycline-HCl

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Authors

Farah Hamad Farah
Department of Pharmaceutics, College of Pharmacy and Health Sciences, Ajman University of Science and Technology, United Arab Emirates
Omer Ali Attef
Department of Pharmaceutical Chemistry, College of Pharmacy and Health Sciences, Ajman University of Science and Technology, United Arab Emirates
Abdul-Azim Ahmed Ali
Department of Pharmaceutics, College of Pharmacy and Health Sciences, Ajman University of Science and Technology, United Arab Emirates

Abstract


The influence of khat on both in-vitro and in-vivo availability of tetracycline-HCl has been evaluated. The in-vitro availability data have reflected a statistically significant interaction between khat extract and tetracycline-HCl in two buffer solutions simulating intestinal and gastric media (phosphate buffer-pH 7 and 0.1 HCl-pH 1.2 respectively). In the in-vivo availability studies, ten adult healthy Yemeni volunteers participated. The obtained in-vivo availability data indicated a statistically significant reduction in most pharmacokinetics parameters. A statistically significant % reduction in the maximum plasma tetracycline-HCl concentration (Cmax) and absorption rate constant (Ka) as well as a significant enhancement of time to reach the peak plasma concentration (Tmax), were observed as a result of taking tetracycline-HCl just before khat chewing (trial B) and more pronounce during khat chewing (trial D) compared to the control (trial C). In addition a statistically significant % reduction in area under curve (AUC0→∞) has been observed reflecting a reduction in the extent of in-vivo tetracycline-HCl availability as a result of khat chewing. Statistically significant % reductions in the biologic half-life (t½) and elimination rate constant (Kel) were also observed.The reduction in tetracycline-HCl concentration when mixed with khat extract, as shown by in-vitro data, may reflect a possible formation of tetracycline-HCl complexes with one or more of khat constituents. The reduction in the rate and extent of in-vivo tetracycline-HCl availability as a result of khat chewing, may be due to the possible formation of non-absorbable tetracycline-HCl complexes with one or more of khat constituents or possible delaying of gastric emptying induced by khat that may prolong the resident time of tetracycline-HCl in the stomach leading to its possible degradation into the less antimicrobial active form epitetracycline.

Keywords


Availability, Pharmacokinetics Parameters, Tetracycline-HCl, Khat.