Sovernber 1966
XFFECT O F D R U G S O K X S c O R B l C ,kCID EXCHETION
941
The Effect of Probenecid, Phenylbutazone, and Their Analogs on the Excretion of L-Ascorbic Acid in Rats' PETER G. DATTOX, ~ I A R TAIt .SWEISS, AND JAMES 11. PEREL -\ L W 1-oi.i; C-nicei aily Research Sei vice, Goldwafer Mernom'al Hospital, 1C'eljare Island, -\-el*. York, ,\'el*. York
Received A p r i l 20, 19/36' Probenecid, phenylbiitazone, aiid a number of their analog. were studied in regard to their effect on the biosynthesis of L-ascwbic acid in t,he rat. An esamiiiation of several physicochemical properties led to a correlation between "lipid solubility" (partition coefficient between peanut oil and pH 7.4 buffer) and the stimulation of the glucuronic acid pathway for the probenecid series. The major reqiiirement for the effect is not stringent, a relatively low "lipid solubility" is required. In general, disitbstitution of the sulfonamide hydrogens by alkyl group.: resulted in increased "lipid aolubility," whereas monosubstitution had a minor infliieiice. Phenylbutazone and most of its analogs, which are already highly lipophilic, also were stim1llatory. I t i.5 proposed that the measiirement of L-ascorbic acid escretion, which is indicative of the rate of its biosynthesis in rats, is a convenient model for the prediction of the stimulation of drug metabolizing activity.
J-arious structurally unrelated conipou~idssuch as barbital, phenylbutazone, and 3-methylcholanthrene increase the biosynthesis, metaboliqm, and excretion of L-ascorbic acid in the r a t ; this has been shown t o involve an enhancement of the conversion of hexoses t o L-ascorbic acid cia D-glucuronic and L-gulonic acids.?l3 The present study is an attempt t o find a correlation betn-een the increased L-ascorbic acid excretion in the rat and selected physicochemical properties of certain subbtances producing these effects.
Experimental Section l l a l e albino \Tistar rata weighing between 170 arid 300 g were obtained from Twin Oaks Farms, lIoorestown, S . J. l1ale Sherman rats (same range) were obtained from Camm Research, Kayiie, X . J. They were giveii .iO-i0 ml daily of a 1 : 1 mixture of evaporated milk (Carnatioii@,) and water 1 week prior to, aiid diiririg the experiments (a low ascorbic acid diet). The rats were kept in roiind individual metabolism cages placed over a 2j-cm polyethylene fiinnel; iron wire mesh was used to catch the feces. The lirine was collected dailj- in 5 ml of 8% oxalic arid. Only rats excreting less than 1 mg/24 hr of L-ascorbic acid during a control period were used. Uiider ether anesthesia rat blood was collected by cardiac punctiire iisiiig heparin as an aiiticoagiilaiit. Only one .>amplewas withdrawn from each rat. Probenecid and its analogs were a gift of Drs. James AI. Spragiie aiid John E. Baer (llerck Sharp arid Dohme, West Point, Pa.). The phenylbutazone analogs were synthesized by Dr. F. Hiifliger and his colleagues (J. R . Geigy, Basel). The compoiiiids were S a O H : the solutions were dissolved in a miiiimum of 2.5 theii adiunted to pH 7.4 with 2 c , acetic acid and then diluted with water aiid isotonic saline t o a 2.5% w/v solution in such a manner that the final solution was SOc; saline. 1,2-Dipheny1-4-isopropylpyrazolidirie-3,j-dioiie and l-(p-hydroxyphenyl)-2-phenylf-biitylpyrazolidiiie-a,S-dioiie were given intraperitoneally in a single dose of 51) mg daily for 4 days.. Probenecid and its analogs (with the exception of the di-nbiityl aiialog) were injected iiitraperitoiieally accordiiig to the following schedriles: on day 1 and 2, 125 mg/kg at 10 AlI mid l2,5 nig/kg at 2 P31: oil day 3, 250 nig/kg at 10 A11 aiid 250 mg/kg at 2 P l l . If an analog did not prodlire a sigiiificaiit effect, the rats were maintained on the diet. One week later they were A\-
( 1 ) This investigation x a s supported by Grant S o . A M 04724 from t h e National Institutes of Health and by t h e Health Research Council of t h e City of New York under Contracts N o . V-1089 and U-1579. Presented before the 4th Annual lletroyolitan Regional Meeting of the Ken. York and S p n .Jer*e? S e r t i u i i s of the .Amerii.aii ('liemic.al S o < , i r t j ,Srrven- I u r i r i i r r , l l o l ~ ~ ~ k N. r n .I,, , I ' e l ~ ,IHti;. ( 2 ) .I. J . I
