H. Van Gogh

Pharmacokinetic aspects of penicillins, aminoglycosides and chloramphenicol in birds compared to mammals. A review

Based on a review of the literature, a comparison is made of the pharmacokinetics of penicillins, aminoglycosides, and chloramphenicol in birds and mammals. Penicillins in birds are likely to be more dependent for their elimination on biotransformation than in mammals. Amoxycillin had a relatively low availability (0.34) after p.o. administration. Higher doses (2 to 8 times) were needed to achieve the same peak levels in birds and mammals. Aminoglycosides, which for their elimination largely depend on renal excretion by glomerular filtration, show only minor differences in pharmacokinetics between birds and mammals. Chloramphenicol is mainly excreted after biotransformation and large differences in pharmacokinetic parameters are to be found, not only between birds and mammals, but also between avian species.

The effect of testosterone on the plasma disappearance rates of sulphadimidine and antipyrine in castrated dwarf goats.

Plasma disappearance of sulphadimidine and antipyrine was studied in adult castrated dwarf goats before and following pretreatment with testosterone. Comparison was made with entire males before and after castration. Testosterone pretreatment caused a significant increase in the apparent elimination half-life in castrates, whilst in entire males castration caused a significant decrease.

The influence of the injection site on the bioavailability of ampicillin and amoxycillin in beagles

Influence of the injection site on bioavailability in dogs was investigated for injections with ampicillin anhydrate or amoxycillin trihydrate suspensions. Firstly, pharmacokinetic parameters were calculated after IV administration of the sodium salts. Then the dogs were injected in the neck (SC), in the lateral thorax region (SC), in the back (IM) and in the thigh (IM), respectively. The most obvious depot effect was seen after subcutaneous injection of ampicillin in the thorax region, though bioavailability seemed to be low. No differences were seen between the injection sites with amoxycillin. For ampicillin SC injection in the neck seems most favourable; for amoxycillin SC injection may be preferred because it is less burdening. Serum concentrations with amoxycillin were higher and persisted longer than with ampicillin. Further investigation is necessary to determine whether this also counts for tissues or focus of infection.

The effect of tick-borne fever on metabolism and renal clearance of sulfadimidine in goats

The tick-borne fever (TBF) model was used to study the effect of fever on the metabolism of sulfadimidine in goats. During TBF the elimination half-lives were prolonged, and the renal clearance values of sulfadimidine and the majority of its metabolites were markedly diminished compared with those in the uninfected state. During TBF the steady-state levels of the hydroxy metabolites were markedly increased. TBF reduced the extent of hydroxymethylation of the pyrimidine side chain; TBF did not affect acetylation of sulfadimidine. In one goat a progressive accumulation of the metabolites was noticed.

Influence of gestation on the pharmacokinetics of four sulphonamides in goats.

The influence of gestation on the pharmacokinetics of four sulphonamides was studied in goats before, during and after pregnancy. Similar doses were given as intravenous boluses of 50 mg kg-1 each. Results were compared with those of non-pregnant goats to eliminate seasonal effects. With sulphadimidine elimination was mainly apparently first-order. In gestating goats the mean residence times decreased and mean plasma clearance rates increased with sulphadimidine during pregnancy, but this effect was continued after kidding at least until the end of May. The same happened with sulphadimethoxine, but sulphisomidine was not affected. In contrast to the other sulphonamides the mean residence time of sulphadoxine showed a maximum in February in gestating goats, while mean plasma clearance remained constant during and after pregnancy, at a lower level than in September. The mean plasma clearance of sulphadoxine decreased significantly from September to February in the non-pregnant control goats. In May five of six control goats and two of six goats which had kidded showed capacity-limited elimination against only two control goats in the foregoing experiments. With sulphadoxine one animal in the gestation group, but not the same one in each experiment, showed capacity-limited elimination against one, four and three in the control group in December, February and May, respectively. Distribution volumes increased significantly during and after pregnancy with sulphisomidine and sulphadimethoxine. A decrease in distribution volumes was seen in control goats with sulphadimidine, sulphisomidine and sulphadoxine, but was only significant for sulphadoxine. The pregnant uterus could not be recognised as an extra compartment, either in distribution volume nor in the pharmacokinetic model.(ABSTRACT TRUNCATED AT 250 WORDS)

Farmacotherapie in de diergeneeskunde

A survey is given of the drugs and dosage forms which are mostly used in veterinary medicine, with special regard to the differences between veterinary and human medicine.Chemotherapeutics play an important role in pharmacotherapy, especially regarding farm animals (mass medication in intensive farming). Several groups of chemotherapeutic agents,c.q. anthelminthics and pesticides, play a more important role than in human medicine.The application of antimicrobial drugs for growth stimulation and for prevention of infectious diseases, mostly as food additives, as well as the problem of residues of antibiotics in food-stuffs of animal origin are specific to veterinary medicine.Soft ointments in injectors for intramammary use and electuaries in dosing guns are unknown in human practice.Pharmacokinetics show great differences between different animal species, which enhances the difficulty in calculating dosage regimens.A short description is given of the pharmaceutical education of the veterinary students.SamenvattingIn dit artikel wordt een overzicht gegeven van farmaca en toedieningsvormen die in de diergeneeskunde het meest worden toegepast. De nadruk wordt daarbij gelegd op de verschillen met de humane farmacie.In de diergeneeskunde bestaat een verschil in benadering tussen de gezelschapsdieren en de nuts- of landbouwhuisdieren.Chemotherapeutica nemen een belangrijke plaats in de veterinaire farmacotherapie in, vooral in de grote-huisdierenpraktijk (massamedicatie in de bio-industrie). Verschillende groepen chemotherapeutica,. zoals die tegen worminfecties en ectoparasieten, spelen een veel grotere rol dan bij de mens.Specifiek veterinair zijn de nutritieve en preventieve toepassing van antimicrobiële middelen en het probleem van de residuen in voedingsmiddelen. van dierlijke oorsprong.Tussen de diverse diersoorten bestaan yaak aanzienlijke farmacokinetische verschillen. Het doseren van geneesmiddelen bij dieren is dan ook geen eenvoudige zaak.Van de toedieningsvormen worden o.a. het electuarium, in doseerspuiten, en de dikvloeibare zalf in injectoren voor intramammair gebruik alleen veterinair toegepast.Tenslotte wordt de farmacotherapeutische en farmaceutische opleiding van de Studenten in de diergeneeskunde kort beschreven.