Uptake of basic drugs into rat lung granule fraction in vitro

Junko Ishizaki, Koichi Yokogawa, Emi Nakashima, Shoji Ohkuma, Fujio Ichimura

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Abstract

Although basic drugs are distributed widely in various tissues, they are characteristically concentrated in the lung granule fraction. We examined the uptake of seven lipophilic basic drugs into rat lung granule fraction (P2) in vitro and investigated the contributions of drug lipophilicity and lysosomal trapping to the characteristic lung P2 distribution. The uptake of each drug into P2 was examined at various pH values. The drug concentration in P2 was determined by gas chromatography. Biperiden (BP) was rapidly taken up into P2, reaching a maximal concentration within 1 min at pH 7.4 at both 4 °C and 37 °C. Both BP and chlorpromazine uptake into P2 was biphasic. Though the uptake rates of the seven drugs into P2 increased with rising pH, the rate of increase varied for each drug. There was a good correlation between the octanol-water partition coefficient of the non-ionized form (P(oct)) of each drug and the uptake into P2 in the presence or absence of NH4Cl, which inhibits lysosomal trapping. However, uptake into P2 in the presence of NH4Cl showed a stronger P(oct)-dependency. We conclude that the distribution of basic drugs into lung P2 is dependent on both drug lipophilicity and lysosomal uptake.

Original languageEnglish
Pages (from-to)858-861
Number of pages4
JournalBiological and Pharmaceutical Bulletin
Volume21
Issue number8
DOIs
Publication statusPublished - 1998 Jan 1

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Keywords

  • Basic drug
  • Distribution
  • Lipophilicity
  • Lysosome
  • Rat lung granule fraction

ASJC Scopus subject areas

  • Pharmacology
  • Pharmaceutical Science

Cite this

Ishizaki, J., Yokogawa, K., Nakashima, E., Ohkuma, S., & Ichimura, F. (1998). Uptake of basic drugs into rat lung granule fraction in vitro. Biological and Pharmaceutical Bulletin, 21(8), 858-861. https://doi.org/10.1248/bpb.21.858