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Effect of lipophilicity on drug distribution and elimination: Influence of obesity
Author(s) -
Bruno Christopher D.,
Harmatz Jerold S.,
Duan Su X.,
Zhang Qingchen,
Chow Christina R.,
Greenblatt David J.
Publication year - 2021
Publication title -
british journal of clinical pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.216
H-Index - 146
eISSN - 1365-2125
pISSN - 0306-5251
DOI - 10.1111/bcp.14735
Subject(s) - lipophilicity , chemistry , pharmacokinetics , partition coefficient , pharmacology , volume of distribution , in vivo , drug , obesity , distribution (mathematics) , bioavailability , high performance liquid chromatography , medicine , chromatography , biochemistry , biology , mathematical analysis , microbiology and biotechnology , mathematics
Aims For a given passively‐distributed lipophilic drug, the extent of in vivo distribution (pharmacokinetic volume of distribution, V d ) in obese individuals increases in relation to the degree of obesity. The present study had the objective of evaluating drug distribution in relation to in vitro lipophilicity, and the relative increase in V d associated with obesity across a series of drugs. Methods Cohorts of normal‐weight control and obese subjects received single doses of drugs ranging from hydrophilic (acetaminophen, salicylate) to lipophilic (imipramine, verapamil). Lipid solubility was measured by the log‐transformed values of the high‐pressure liquid chromatographic (HPLC) retention index (Log 10 (HPLC)), and the octanol–water partition coefficient (LogP). Results Among normal‐weight controls, V d normalized for protein binding was highly correlated with Log 10 (HPLC) ( R 2 = .65) and with LogP ( R 2 = .78). V d of all drugs was increased in the obese cohort, but the relative increase (compared to controls) for individual drugs was disproportionately greater as lipid solubility increased. Since clearance was unrelated to lipophilicity, the increased V d produced a parallel disproportionate increase in elimination half‐life in the obese cohort that was associated with Log 10 (HPLC) ( R 2 = .62). Conclusion Lipophilicity is a principal correlate of in vivo V d , as well as the increased V d of drugs in obese patients. The consequent prolongation of half‐life in obesity has clinical safety implications in terms of delayed drug accumulation and washout during and after chronic dosage. The magnitude and importance of this effect for a given drug depends on the degree of obesity, as well as the lipid‐solubility of the specific drug.