The influence of the trichloroacetate anion on the n‐octyl alcohol‐aqueous phosphate buffer apparent partition coefficients of various tetracyclines was determined. At acidic pH values, the presence of trichloroacetate caused a significant increase in the apparent partition coefficients of most of the tetracycline analogs studied, presumably through intermolecular ion‐pairing between the positively charged tetracycline moiety and the trichloroacetate anion. From intermediate to mildly alkaline pH values, trichloroacetate had essentially no effect on partitioning. The transfer of compounds such as minocycline and 9‐dimethyl‐amino‐6‐demethyl‐6‐deoxytetracycline to the n‐octyl alcohol phase was not as significantly altered by the addition of trichloroacetate, apparently because the effect of two charged moieties in each of these analogs was not as easily overcome by ion‐pair formation. The alteration of the apparent partition coefficients of the tetracycline antibiotics by intermolecular ion‐pair formation is discussed in terms of its relationship to the absorption of these compounds.
All Science Journal Classification (ASJC) codes
- Pharmaceutical Science
- Ion‐pair formation—effect of trichloroacetate on tetracycline partition behavior
- Tetracycline partition coefficients—trichloroacetate effect, ion‐pair formation
- Trichloroacetate—effect on tetracycline partition coefficients, ion‐pair formation