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Biomedical subjects

J A Bogan

Publications and source records attributed to J A Bogan.

At least 37 records · Page 2Linked to original sources
PubMed1988

Pharmacokinetics and efficacy of triclabendazole in goats with induced fascioliasis.

The pharmacokinetics of triclabendazole were evaluated in normal goats and in goats artificially infected with Fasciola hepatica. Triclabendazole and its metabolites were determined using a novel high performance liquid chromatographic method with fluorimetric detection after solid-phase extraction. In normal goats triclabendazole given orally was metabolized rapidly to its sulphoxide and sulphone derivatives. The maximum plasma concentrations for the sulphoxide and sulphone were similar ranging from 9 to 19 micrograms/ml and these were attained at an average 12.8 and 25.6 h, respectively, after administration. Both metabolites were eliminated slowly from plasma with elimination half-lives of 22.4 h for the sulphoxide and 19.4 h for the sulphone. They persisted at measurable concentrations in plasma for up to seven days. In milk, the two metabolites occurred in low concentrations and none of them was detectable (sulphoxide less than 0.04 microgram/ml, sulphone less than 0.02 microgram/ml) after seven days. The pharmacokinetic behaviour of triclabendazole was not altered in animals with fascioliasis. Efficacy of the drug against immature (six-week) F. hepatica was 100%.

Animals↗
PubMed1988

The pharmacodynamics of ivermectin in sheep and cattle.

The concentrations of ivermectin in the gastrointestinal tract of sheep and cattle were determined after subcutaneous administration of ivermectin. Ivermectin was not detected (limit of detection 1 ng/ml) in abomasal and ruminal fluids either after a normal therapeutic dose of 200 micrograms/kg or even at an increased dose of 2000 micrograms/kg. It was also not detected in abomasal and ruminal fluids of a sheep infected with the abomasal parasite Ostertagia circumcincta. However, ivermectin was detectable at similar concentrations in abomasal mucus and in small intestinal mucus. Excretion of ivermectin was high in bile but the concentrations in small intestinal mucus, distal and proximal to the bile duct opening, were similar. It is hypothesized that the low efficacy of ivermectin against small intestinal nematodes compared with abomasal nematodes is not due to differences in ivermectin concentrations in the predilection sites but is probably due to tachyphylaxis in the nematodes allowing the small intestinal nematodes to re-establish before they have left their predilection site. Ivermectin was excreted in the milk of ewes at concentrations similar to those in plasma. Lambs suckling ivermectin-treated ewes received about 4% of a normal therapeutic dose (200 micrograms/kg) via the milk.

Animals↗
PubMed1988

Parvaquone and buparvaquone: HPLC analysis and comparative pharmacokinetics in cattle.

A high performance liquid chromatographic (HPLC) method for the determination of the antitheilerial drugs parvaquone and buparvaquone in plasma was developed. Both compounds were extracted from plasma with ether. After evaporating the extracts to dryness the residue was dissolved in methanol and an aliquot was injected onto a column (10 cm X 5 mm, i.d.) of ODS-Hypersil (5 mu) with a mobile phase of 0.05 M-Na acetate buffer (pH 3.6)-methanol (15:85, v/v). Detection was at 252 nm. The mean recovery for both compounds was about 92%. This method was used to elucidate their pharmacokinetics in 6 calves after intramuscular administration. The maximum plasma concentration for parvaquone was 6.36 +/- 0.58 micrograms/ml after 0.84 +/- 0.08 h. The corresponding values for buparvaquone were 0.102 +/- 0.030 microgram/ml and 3.17 +/- 0.39 h, respectively. The decay in plasma concentrations for the two drugs was biexponential and the terminal elimination half lives were 11.12 +/- 1.63 h and 26.44 +/- 2.81 h for parvaquone and buparvaquone, respectively.

Animals↗
PubMed1988

Solid-phase extraction and ion-pair reversed-phase HPLC of isometamidium in bovine serum and tissues.

An analytical method has been developed for the determination of isometamidium in bovine serum and tissues. Samples were enzymatically hydrolysed and cleaned up on a solid-phase system (C8 Bond Elut column). The drug was chromatographed by an ion-pair reversed-phase technique using heptane sulphonate as a pairing-ion and triethylamine as a counter-ion reagent. Detection was by fluorescence at 593 nm (excitation = 380 nm). The method is more sensitive and specific than existing methods and it is currently being used in evaluating the pharmacokinetics of isometamidium in cattle.

Animals↗
PubMed1988

Efficacy of ivermectin against Cooperia curticei infection in sheep.

Lambs were inoculated with a single dose of Cooperia curticei. Subcutaneous administration of ivermectin at a dosage of 200 micrograms/kg of body weight resulted in 61.1% and 90.4% anthelmintic efficacy, when measured at 7 and 14 days after treatment, respectively. In the treatment groups, parasites that remained were located more distally in the small intestine than those in the lambs in the control groups.

Animals↗
PubMed1988

Pharmacokinetic and histopathological investigations of isometamidium in cattle.

The absorption and distribution patterns of the trypanocidal drug isometamidium and its effect on tissues in cattle were characterised. After intramuscular administration of a prophylactic dose of 0.5 mg kg-1 bodyweight, the drug was rapidly detectable in serum at a mean maximum concentration of only 20 ng ml-1 and declined to concentrations of lower than 10 ng ml-1 within two hours. High drug concentrations were maintained at the injection site and in the liver and kidney for at least six weeks. At the injection site, tissue damage was severe and extensive, whereas in the liver and kidney no histopathological lesions were seen.

Absorption↗
PubMed1987

Penicillin therapy of spontaneous streptococcal meningitis in pigs.

Oral prophylactic medication with either procaine penicillin G or a mixture of chlortetracycline, sulphadimidine and procaine penicillin G reduced the incidence of streptococcal meningitis in a herd of pigs with a high recorded prevalence of the disease, but to a significant extent (P less than 0.01) only in those pigs receiving procaine penicillin G. Subsequent studies showed that after oral administration of procaine penicillin G, benzylpenicillin was detectable in plasma only at very low concentration and similar results were obtained using the potassium salt of penicillin G. However, phenoxymethyl penicillin administered orally provided high plasma concentrations of this drug. A further investigation demonstrated that despite the low plasma concentrations of penicillin after oral administration of the procaine salt, gastrointestinal and urinary concentrations of the drug were relatively high for up to five hours.

Administration, Oral↗
PubMed1987

The pharmacodynamics of the flukicidal salicylanilides, rafoxanide, closantel and oxyclosanide.

The pharmacokinetics of oxyclosanide, rafoxanide and closantel were investigated in sheep (n = 5). All three drugs were extensively (greater than 99%) bound to plasma proteins and the plasma concentration/time curve was best described by a tri-exponential equation. Closantel and rafoxanide had long terminal half-lives (mean 14.5 and 16.6 days, respectively) compared with oxyclosanide (mean 6.4 days). In a study of the efficacy of rafoxanide against Fasciola hepatica, a dose rate of 7.5 mg kg-1 against 6-week-old flukes appeared to be similarly effective to a dose rate of 2.5 mg kg-1 against 10-week-old flukes (86% and 88% efficacy, respectively), as assessed at autopsies carried out on all sheep when the flukes were 14 weeks old. Part of this putative efficacy against immature flukes may be due to rafoxanide persisting in the plasma and affecting the mature flukes when they reach the bile ducts.

Animals↗
PubMed1987

Effect of sodium cromoglycate on the response to Ostertagia circumcincta in adult sheep.

Serum pepsinogen concentrations rose more rapidly and to higher levels in adult sheep infected with Ostertagia circumcincta and treated orally with the mast cell stabilising agent sodium cromoglycate than they did in adult sheep infected with the parasite which remained untreated. Sodium cromoglycate did not affect the serum pepsinogen concentrations or abomasal pH in uninfected sheep.

Animals↗
PubMed1986

Pharmacokinetics of albendazole in man.

The pharmacokinetics of albendazole were investigated in healthy volunteers and in patients receiving albendazole for treatment of hydatid disease. Unchanged albendazole was below detectable limits in plasma, urine, bile and cyst fluid. The major metabolite present in all fluids was the sulfoxide. Maximum concentrations of albendazole sulfoxide in plasma were very variable, probably due to variable absorption of albendazole.

Absorption↗
PubMed1985

Effect of parasitism with Ostertagia circumcincta on pharmacokinetics of fenbendazole in sheep.

Plasma and abomasal fluid concentrations of fenbendazole and its two major metabolites in sheep experimentally infected with Ostertagia circumcincta were compared with those in the same sheep when non-parasitised. Bio-availability of the drug was reduced in the parasitised state. There was also a reduction in the proportion of drug present in the form of metabolites in parasitised as compared with non-parasitised animals.

Abomasum↗