Seemi Gul, Nasim Akhtar, Iffat Ara, Majeeda Tahira.
Bucccal absorption of Allopurinol hydrochloride, and its applications as an in vivo/vitro model of passive drug transfer through lipid membranes.
Pak Postgrad Med J Jan ;18(1):32-4.

Introduction: Permeability of any drug depends in part on to its lipophilicity. Lipophilicity is estimated from octanol / buffer solubility ratio of the drug. On the other hand Buccal absorpiton test could be used as an in vivo model of passive drugs transfer through biological membranes. Aim: The aim of the present study was to find out the innate lipid solubility of Allopurinol hydrochloride in vitro` by measuring its oil / water partition coefficient at various pH in three test samples and in vivo by the buccal absorption test (in vivo) of drug in six volunteers of either sex with age 20 – 60 years. Results: Mean percentage bucal partitioning of the drug at pH 6-10 was form 37.12 to 13.08 respectively. M percentage of 1-octanol partitioning at pH 6-10 was form 41.2 to 5.4. Correlation coefficient between n percentage buccal partitioning and 1-octanol partitioning over the pH range 6-10 showed highly signifi difference. Conclusion: Ionized form of allopurinol is more lipid soluble while very little of unionized moiety of this drug partitioned in lipid phase. Decrease in lipid solubility (both in vitro and in vivo) of unionized fraction of allopurinol hydrochloride needs further evaluation.

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