Allopurinol
Enzymatic antioxidant defence mechanism in rat intestinal tissue is changed after ischemia-reperfusion. Effects of an allopurinol plus antioxidant combination.

Kacmaz M, Ozturk HS, Karaayvaz M, Guven C, Durak I.

Department of Biochemistry, Ibn-I Hospital, Ankara, Turkey.

OBJECTIVES: To establish the antioxidant status of rat intestinal tissues after ischemia-reperfusion and to determine if pretreatment with an allopurinol and antioxidant vitamin combination gives any protection against mucosal injury. EXPERIMENTAL ANIMALS: Twenty rats were divided into 4 groups of 5 animals each. METHODS: Group 1 (control) rats were not subjected to ischemia-reperfusion and received no allopurinol plus vitamin combination; group 2 rats received vitamins C (200 mg/kg) and E (100 mg/kg) and allopurinol (50 mg/kg) combination daily for 3 days preoperatively; group 3 rats were subjected to ischemia-reperfusion only; and group 4 rats were subjected to ischemia-reperfusion and received the vitamin and allopurinol combination. MAIN OUTCOME MEASURES: Activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT) enzymes, the level of thiobarbituric acid-reagent substances (TBARS) and histologic grading of tissue samples. RESULTS: SOD and GSH-Px activities were decreased, but the CAT activity and TBARS level increased. Pretreatment of the rats with the allopurinol-vitamin C-vitamin E combination did not have any significant effect on the enzyme activities. However, it resulted in important reductions in the TBARS tissue levels. Histologic investigation revealed significant mucosal injury in group 3 rats compared with group 4 rats (mean [and standard deviation] for grading, 4.6 [0.5] versus 1.8 [0.4]). CONCLUSIONS: The enzymatic antioxidant defence system was significantly changed after ischemia-reperfusion and intestinal tissue was exposed to increased oxidant stress, the results of which were peroxidation of some cellular structures and increased concentrations of oxidative products. Although antioxidant treatment did not drastically affect the enzyme activities or afford complete protection of cellular structures against deformation, it apparently could eliminate oxygen radicals and prevent peroxidative reactions.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10593243&dopt=Abstract allopurinol Zyloprim



Allopurinol
Formulation development of allopurinol suppositories and injectables.

Lee DK, Wang DP.

Department of Pharmacy, Kaoshiung Veterans General Hospital, Kaoshiung, Taiwan, R.O.C.

Allopurinol was formulated into injectable and suppository dosage forms. The injectable formulation was prepared by dissolving allopurinol in a cosolvent system consisting of dimethyl sulfoxide (DMSO) and propylene glycol (v/v = 50/50). The stability of allopurinol in the cosolvent system was studied under accelerated storage conditions, and results indicate first-order degradation kinetics with an activation energy of 24.3 kcal/mol. The development of suppository dosage forms was performed by formulating allopurinol with polyethylene glycol (PEG) mixtures of different molecular weights. In vitro release profiles of suppositories formulated with different polyethylene bases were obtained in the pH 7.4 buffer solution using the USP 23 paddle method at 100 rpm. Results indicate that the release rate of the suppository formulations containing PEG 1500/PEG 4000 at the ratio (w/w) of 2.5/10 to 10/2.5 appeared to be similar. However, the addition of sodium lauryl sulfate in the suppository decreased the release rate of allopurinol significantly. A future study to establish in vitro/in vivo correlation (iv/ivc) is suggested.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10596359&dopt=Abstract allopurinol Zyloprim



Allopurinol
PCR follow-up examination after treatment of canine leishmaniosis (CaL).

Steuber S, Moritz A, Schirrmann I, Greiner M.

Federal Institute for Health Protection of Consumers and Veterinary Medicine (BgVV), Berlin, Germany.

A study has been performed to investigate the usefulness of the polymerase chain reaction (PCR) for both the diagnosis and the follow-up after treatment of canine leishmaniosis (CaL). Blood samples (PBL) and/or bone marrow aspirates (BM) could be examined in a total of 18 confirmed cases of primary CaL. PBL was PCR-positive in 87%, whereas the BM was found to be positive in all cases (n=14) tested. PBL and BM from a total of 13 patients were submitted to PCR examinations after meglumine antimoniate (Glucantime) treatment. Only one dog showed a negative PCR after 2 treatment cycles (days 1-2: 50 mg/kg bw; days 3-10: 100 mg/kg bw). Examination of the PBL and BM after 15 months remained further PCR negative. All other dogs, from which four were pretreated with allopurinol up to 5 weeks, continued to be positive (92%) at least in the BM. Ten dogs could be monitored by means of the PCR after allopurinol treatment (2 x 10 mg/kg/bw/day/) either as a monodrug therapy in seven or as a successive combination with Glucantime in three cases. Two out of three dogs which showed good clinical improvement after daily administration for five weeks were likewise PCR negative in both the PBL and the BM. The four other dogs remained positive after the single therapy with allopurinol up to 5 weeks. A further three dogs were treated with allopurinol for 5 weeks, 6 and 20 month, respectively, after being clinically cured with Glucantime. Two of them were PCR negative in the PBL and BM after 5 weeks and 20 month, respectively. The results presented suggest that longterm treatment with allopurinol has some therapeutic benefit in CaL especially when administered following treatment with the pentavalent antimonial Glucantime.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10622624&dopt=Abstract allopurinol Zyloprim



Allopurinol
Improvement of availability of allopurinol from pharmaceutical dosage forms I - suppositories.

Samy EM, Hassan MA, Tous SS, Rhodes CT.

Deptartment of Industrial Pharmacy, Faculty of Pharmacy, Assiut University, Assiut, Egypt.

Solid dispersion and crystallization of a very slightly water-soluble drug, allopurinol, were prepared using urea, sodium salicylate and beta-cyclodextrin (beta-CD) as carriers. The spectroscopic infra-red (IR), differential scanning calorimetry (DSC) and powder X-ray diffractometry (PXRD) data indicate a role of these carriers in decreasing the crystallinity of allopurinol and complexing abilities. Solid dispersion and crystallization of the drug with these carriers were used in suppository formulations to investigate their role in enhancement of drug release through the membrane barrier. The bases used included Suppocire AM and the mixture of polyethylene glycols (PEGs). The release rates of allopurinol from lipophilic and hydrophilic suppository bases were examined and compared with those obtained for their inclusion compounds incorporated in the same bases. The prepared suppositories were evaluated for in-vitro drug release, when fresh and on storage. The release of pure allopurinol from the lipophilic base was remarkably higher than that from the hydrophilic one. The release of allopurinol from lipophilic as well as hydrophilic bases was significantly enhanced by crystallization of the drug from 5% w/v of sodium salicylate. Allopurinol crystallized from sodium salicylate, showed enhanced release reaching about 100% in 1 h from the Suppocire AM base. The obtained data from these experiments proved the superiority of the PEG formulations containing coevaporates of the drug to sodium salicylate, ratio 1:1, or of the drug to beta-CD, ratio 1:2; T(90%),12 and 36 min, respectively. A significant decrease of uric acid excretion in rabbits was observed after rectal administration of suppositories containing allopurinol crystallized from sodium salicylate.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10704894&dopt=Abstract allopurinol Zyloprim



Allopurinol
Allopurinol encapsulated in polycyanoacrylate nanoparticles as potential lysosomatropic carrier: preparation and trypanocidal activity.

Gonzalez-Martin G, Figueroa C, Merino I, Osuna A.

Catholic University of Chile, Santiago, ggonzale puc.cl

The activity of allopurinol-loaded polyethylcyanoacrylate nanoparticles against Trypanosoma cruzi was compared to that of free allopurinol using in vitro cultures of epimastigotes. Ethylcyanoacrylate nanoparticles were prepared by an emulsion polymerization process, and formulations containing different concentrations of allopurinol, polyethylcyanoacrylate and surfactants were investigated and analyzed in size and amount of drug entrapped. The nanoparticles obtained were less than 200 nm in size, as measured by electron microscopy and cytometry. The peak amount of allopurinol entrapped in the nanoparticles was 62.8+/-1.9 microg mg(-1) of nanoparticles using 400 microl of polyethylcyanoacrylate, 200 microl of surfactant (Tween 20) and 20 mg of allopurinol in 50 ml of polymerization medium and the association efficiency was 100.7%. After 6 h of incubation at pH 7.4 the release of allopurinol from the nanoparticles was 7.4%, while at pH 1.2 only 3.1% was released after 4-6 h (t=42.8, P<0.0001). The in vitro studies, using cultures of T. cruzi epimastigotes, demonstrated considerable increases in the trypanocidal activity of the allopurinol-loaded nanoparticles in comparison with a standard solution of allopurinol (91.5 vs. 45.9%) at an allopurinol concentration of 16.7 microg ml(-1). In addition, it was shown that the unloaded nanoparticles, by mechanisms not completely elucidated, had a trypanocidal activity similar to that of standard solutions of allopurinol. To study cytotoxicity, increasing concentrations of unloaded nanoparticles were incubated on vero-line cell cultures. The concentration that killed 50% cells was 200 microg ml(-1), four times higher than that necessary to kill 50% of T. cruzi. It is concluded that the polyethylcyanoacrylate nanoparticles constitute a good carrier of drugs against the T. cruzi. The allopurinol loaded-nanoparticles significantly increased the trypanocidal activity in comparison to the free drug.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10704896&dopt=Abstract allopurinol Zyloprim



Allopurinol
Allopurinol, an inhibitor of xanthine oxidase, improves the development of IVM/IVF bovine embryos (>4 cell) in vitro under certain culture conditions.

Iwata H, Akamatsu S, Minami N, Yamada M.

Kobe City Horticulture Promoting Association, Kobe, Japan. QYM04636 niftyserve.or.jp

To determine the origin of free oxygen radicals in the culture medium of bovine embryos, the effect of allopurinol, an inhibitor of xanthine oxidase, on the development of embryos (>4 cell) in modified synthetic oviduct fluid (m-SOF) medium was examined. When embryos were cultured in the presence of 0.2 mM allopurinol under high oxygen tension (5% CO2 in air), the blastocyst rate significantly (P<0.05) increased compared with the absence of allopurinol (allopurinol (+) 42 vs. (-) 25%; Day 6, 63 vs. 51%; Day 7, 69 vs. 58%; Day 8). However, allopurinol had no effect on embryo development under low oxygen tension (5% CO2, 5% O2, 90% N2). Moreover, it was found that the developmental rate and the total cell number of blastocysts decreased (development rate: 60 vs. 28%, cell number: 132 vs. 74) when the embryos were cultured in medium containing 0.01 U/mL xanthine oxidase (XOD) and 0.1 mM hypoxanthine (HXT), and the damaging effect of XOD and HXT was removed by the addition of 0.2 mM allopurinol. The beneficial effect of allopurinol was also observed when the glucose concentration was increased to 4.5 mM from 1.5 mM (control: 22% vs. allopurinol: 34%; Day 8), but no beneficial effects were observed in the media without glucose (control: 55% vs. allopurinol: 59%). Taken together, these results suggested that a portion of the free oxygen radicals are generated from the XOD and HXT reactions under culture conditions, and this generation is enhanced by high oxygen tension in the gas atmosphere or by high glucose concentrations in the medium.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10729046&dopt=Abstract allopurinol Zyloprim