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Biomedical subjects

H van Gogh

Publications and source records attributed to H van Gogh.

At least 19 recordsLinked to original sources
PubMed1991

The influence of disease on feed and water consumption and on pharmacokinetics of orally administered oxytetracycline in pigs.

In the present study the feed and water consumption and pharmacokinetic parameters of orally administered oxytetracycline were compared in clinically healthy pigs and in the same pigs following a challenge with Actinobacillus (Haemophilus) pleuropneumoniae toxins. Endobronchial challenge with A. pleuropneumniae toxins was accompanied by anorexia, increased lassitude, labored breathing, fever, and increased white blood cell counts. Pleuropneumonia was evident in all pigs on autopsy. Following the challenge, both feed and water consumption were markedly reduced. In contrast to recommendations in the literature, it is concluded that drugs should not be administered to pneumonic pigs via water. In healthy pigs the oral bioavailability of oxytetracycline (50 mg/kg), given on an empty stomach, was 4.8% and the elimination half-life (t1/2 beta) was 5.92 h. After challenge, the pigs showed great variation in oxytetracycline plasma concentrations. In addition, the mean computed elimination rate constant (beta), t1/2 beta, the area under the plasma concentration-time curve (AUC), and clearance in pneumonic pigs differed significantly (P less than .05) from the values found in healthy pigs. The elimination half-life (t1/2 beta), AUC, and volume of distribution (Vd area) were increased. In diseased pigs the mean of maximum plasma concentrations (.87 micrograms/ml) was reached after 7 h, in contrast to 1.74 h (1.87 micrograms/ml) in the healthy pigs.

Actinobacillus Infections↗
PubMed1990

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.

Absorption↗
PubMed1990

The pharmacokinetics of oxytetracycline following intravenous administration in healthy and diseased pigs.

The pharmacokinetics of oxytetracycline (OTC) were studied in healthy pigs and in pigs endobronchially inoculated with Actinobacillus pleuropneumoniae toxins. In two groups of seven pigs OTC was administered intravenously in a single dose of 10 or 50 mg/kg, respectively. OTC was administered to clinically healthy pigs and 7 days later at 3 h after a challenge with A. pleuropneumoniae toxins. Pneumonia developed in toxin-treated pigs. In the challenged pigs there was a decreased distribution-rate constant (alpha) and a significantly increased elimination-rate constant (beta) (P less than 0.05). Moreover, the apparent volume of distribution (Vd beta) was decreased. The elimination half-lives (t1/2 beta) were approximately 6 h in the healthy pigs and 5 h in the diseased animals. There was no difference in the pharmacokinetic profile of OTC following administration of 50 mg/kg compared to 10 mg/kg.

Actinobacillus Infections↗
PubMed1989

Pharmacokinetics and metabolism of sulphadimidine in kids at 12 and 18 weeks of age.

The pharmacokinetics and metabolism of sulphadimidine (SDM) following intravenous administration of 100 mg/kg were studied in seven dwarf preruminant kids at 12 weeks of age, and again at the ruminant stage, when the animals were 18 weeks old. The persistence of SDM in 18-week-old kids was prolonged in comparison to the 12-week-old animals: a lower total body clearance and a prolonged elimination of SDM were obtained in the older animals. The renal clearance values of SDM and its metabolites were the same at both ages. The decrease of SDM clearance is related to the significant reduction in SDM hydroxylation at the older age. The reduced oxidative hepatic metabolism may result from the sexual maturation of the kids.

Age Factors↗
PubMed1989

Pharmacokinetics of three formulations of diphenylhydantoin in the dog.

The pharmacokinetics of the sodium salt of diphenylhydantoin was studied in three healthy dogs, using three formulations, a capsule, a tablet and a suspension. The results were essentially the same for all three formulations. The serum half life after intravenous injection ranged from 3.1 to 3.6 hours before and 1.3 to 1.6 hours after a two-week period of oral treatment. The bioavailability of the formulations varied from 43 to 54 per cent. Serum levels likely to be required for canine therapy could not be maintained with any of the formulations used in this experiment.

Animals↗
PubMed1988

Some pharmacokinetic data of aditoprim and trimethoprim in healthy and tick-borne fever infected dwarf goats.

Aditoprim (AP) is a new dihydrofolate reductase inhibitor, which is structurally related to trimethoprim (TMP). The pharmacokinetics of AP (10 mg/kg) and TMP (20 mg/kg) were assessed in healthy dwarf goats. Therapeutic efficacy against rickettsial infections was tested in tick-borne fever (TBF) infected goats. The animals were given TMP (n = 5) or AP (n = 5) by i.v. injection, and subsequently the drugs were administered orally (same groups, similar doses). Finally, both groups were infected with TBF and the i.v. experiment was repeated. Plasma concentration-time curves for both drugs followed first-order two-compartment decay. For TMP, mean t1/2 beta +/- SEM (h) was 0.84 +/- 0.06 (i.v. control) and 0.90 +/- 0.06 (i.v. infected), respectively, whereas for AP values of 8.00 +/- 0.31 (i.v. control) and 10.28 +/- 0.67 (i.v. infected) were obtained (P less than 0.05). Mean Vd beta +/- SEM values (l/kg) were 3.84 +/- 0.27 (i.v. control) and 4.07 +/- 0.85 (i.v. infected) for TMP (NS) and 7.02 +/- 0.63 vs 9.29 +/- 0.21 (P less than 0.05) for AP. After i.v. injection, rumen fluid concentrations of AP were significantly (P less than 0.05) higher and more persistent than those of TMP. For AP, the plasma and rumen fluid concentrations at 3 h were 1.20 +/- 0.06 micrograms/ml and 0.85 +/- 0.17 microgram/ml, respectively. After oral administration of TMP, Cmax in plasma was 0.12 +/- 0.01 microgram/ml and the maximum was reached after 1.2 +/- 0.16 h; systemic bioavailability (F) was 10.3% (relative to AUC i.v.). Oral treatment with AP resulted in a Cmax value of 0.21 +/- 0.02 microgram/ml with Tmax of 22.5 +/- 1.65 h and a F value of 71%. Based on WBC, serum ALP and rectal temperature responses, it was concluded that both TMP and AP were inactive against Ehrlichia phagocytophila.

Administration, Oral↗
PubMed1988

The effect of testosterone and rutting on the metabolism and pharmacokinetics of sulphadimidine in goats.

After testosterone pretreatment of castrated goats and during the rutting season of adult entire male goats, the oxidative metabolism of sulphadimidine (SDM) was inhibited markedly compared with the castrated control state of these animals. The oxidation of the 5 position (yielding 5-hydroxysulphadimidine) and of the 6-hydroxymethyl group (yielding 6-carboxysulphadimidine) was decreased equally, with that of the methyl group at the pyrimidine side chain itself being 6-hydroxymethylsulphadimidine (CH2OH), whereas the acetylation pathway was unaffected by testosterone. The consequence of altered metabolism by testosterone was a prolongation of SDM presence in the body. Effects on protein binding of the CH2OH metabolite and on the renal clearance of SDM were also investigated.

Animals↗
PubMed1988

Effect of trenbolone and testosterone on the plasma elimination rates of sulfamethazine, trimethoprim, and antipyrine in female dwarf goats.

Plasma elimination rates of sulfamethazine (100 mg/kg of body weight, IV), trimethoprim (20 mg/kg, IV), and antipyrine (35 mg/kg, IV) were studied in adult female dwarf goats (n = 5) before and after implantation with trenbolone acetate (5 mg/kg). Pretreatment with trenbolone caused a significant decrease in the elimination rate of the drugs tested: for sulfamethazine, 5 times; for antipyrine, 3 times; and for trimethoprim, 2 times. After treatment with testosterone (1 mg/kg, SC, twice weekly for 2.5 weeks), female goats (n = 5) had a similar decrease in the elimination rate of sulfamethazine. Other induced effects included a change in social behavior, a lower voice, and the development of a typical billy goat-like odor. Plasma creatinine concentrations after androgen administration were significantly higher than those before androgen administration; changes were not observed in plasma urea values. Because of the differences observed, we believe that more attention should be paid to the effects of androgenic agents on drug kinetic properties, with particular reference to studies on clinical efficacy, side effects, and drug residues in food products.

Animals↗
PubMed1987

Pharmacokinetics of three sulphonamides in ruminant and preruminant kids.

The pharmacokinetic properties of three sulphonamides were determined in ruminant and preruminant kids after oral and intravenous administration. First, sulphisomidine (SIM, 50 mg kg-1) and sulphadoxine (SDX, 30 mg kg-1) were given to seven kids, 10 to 12 weeks old, while on a milk replacer diet and again at 15 to 18 weeks when fed roughage. Secondly, SIM (100 mg kg-1) and sulphadimidine (SDD, 100 mg kg-1) were given at six to nine, 12 to 15 and 18 to 21 weeks old to eight kids, of which four were fed milk replacer and four were with their mothers (with access to roughage) until 15 weeks, after which all were fed roughage only. SDX and SDD exhibited non-linear (or capacity limited) absorption after oral dosage, suggesting possible active absorption mechanisms, and both drugs also showed non-linear elimination. Intravenous curves for SDD and SIM indicated that recycling occurred. With SDX, ruminant kids showed poorer systemic availability after oral dosage, shorter t1/2(el) and higher B than did preruminants. For SDD, ruminant kids had lower Vd and higher B than preruminants. SIM's t1/2(el) tended to shorten and beta to increase in both groups throughout the experiment. Not all differences between ruminants and preruminants in sulphonamide pharmacokinetics could be explained by the accumulation of acidic forestomach contents and the change of urine pH from acid to alkaline in the maturing ruminant. Other potential contributing factors require investigation, including possible alterations in hepatic drug metabolism. Of the three drugs tested, SDX might be the most satisfactory for therapeutic use in preruminant animals, because it has good bioavailability after oral administration and long t1/2(el).

Absorption↗
PubMed1986

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.

Animals↗
PubMed1986

Bioavailability and pharmacokinetics of ampicillin and amoxycillin from tablets, capsules and long-acting preparations in the homing pigeon (Columba livia).

Three ampicillin and three amoxycillin formulations (tablets and capsules, administered orally, and oily suspensions, injected intramuscularly (i.m.) and subcutaneously (s.c.] were studied in twenty adult homing pigeons (Columba livia). Bioavailability, pharmacokinetics and recovery were determined for each product and administration route. A standard dose of 50 mg/pigeon or 100 mg/kg was used in each study. The mean availability calculated for each of these preparations was 7% for ampicillin anhydrate tablets, 22% for amoxycillin trihydrate tablets, 17% for ampicillin trihydrate capsules, 67% for amoxycillin trihydrate capsules, 46% for ampicillin oily suspension i.m., 67% for amoxycillin oily suspension i.m. and 43% for amoxycillin oily suspension s.c. The blood concentration-time curves for the tablets were very scattered, which was far less the case for the capsules. The maximum blood concentration (Cmax) for amoxycillin was twice as high as for ampicillin. The Cmax resulting from the oily suspensions administered i.m. were low (4.35 +/- 1.05 and 5.04 +/- 1.36 mg/l, for ampicillin and amoxycillin, respectively). The Tmax for ampicillin was 10 h and for amoxycillin it was 0.9 h after administration. Both curves showed biphasic absorption, the initial peak representing an absorption and a distribution phase and the second part reflecting the 'depot-nature' of the drug. After the s.c. administration of the amoxycillin oily suspension the same pattern was found, but the Cmax, which was found at 2.13 +/- 1.03 h after administration, was low (2.81 +/- 0.68 mg/l).(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1986

Chemotherapy and pharmacokinetics of some antimicrobial agents in healthy dwarf goats and those infected with Ehrlichia phagocytophila (tick-borne fever).

The therapeutic efficacy and pharmacokinetics of oxytetracycline (10 mg kg-1), ampicillin (20 mg kg-1) and a combination (TSS) of trimethoprim (20 mg kg-1), sulphadimidine (50 mg kg-1) and sulphamethylphenazole (50 mg kg-1) were investigated in normal dwarf goats and in those infected with Ehrlichia phagocytophila. Goats given oxytetracycline or TSS intravenously showed improvement, whereas ampicillin was ineffective. The infected goats had significantly prolonged elimination half-life values for sulphadimidine and oxytetracycline. The disposition kinetics of ampicillin and sulphamethylphenazole showed no marked differences between the healthy and infected animals. The tick-borne fever model used in the present study can be of value in testing the therapeutic efficacy and pharmacokinetics of chemotherapeutic agents in rickettsial infections.

Animals↗
PubMed1985

[Gentamicin: various pharmacotherapeutic aspects in comparison with other aminoglycosides].

Gentamicin may be used in the treatment of infection with gram-negative bacteria including Pseudomonas spp and Proteus spp. Resistance will only appear in suboptimal or too prolonged courses of treatment and usually is due to 'multi-step mutation'. This resistance may be prevented, among others, by combined treatment with gentamicin and an antibiotic of the beta lactam group. When gentamicin is used correctly, it will have few toxic side-effects. Thus, 3 mg/kg of body weight three times daily will usually be indicated to ensure an optimum therapeutic effect. Parenteral administration of gentamicin would only appear to be useful in cases of bacteraemia and/or bacterial infection of the kidney and/or urinary excretory ducts; in the last-named case, the dose given at one time may be reduced by fifty per cent. Local treatment, the most recent method of which consists in administration by I(ntra-)T(racheal) route, apparently offers more prospects.

Administration, Topical↗
PubMed1984

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.

Aminoglycosides↗
PubMed1983

Clinical pharmacology and pharmacokinetics of flumequine after intravenous, intramuscular and oral administration in pigeons (Columba livia).

The in-vitro activity of flumequine against 157 strains of bacteria isolated from birds was determined. The minimum inhibitory concentration (MIC) of 96.3% of the Enterobacteriaceae, Proteus spp. and Yersinia pseudotuberculosis studied (n = 135) was less than or equal to 1 microgram/ml. Pharmacokinetics of flumequine in pigeons (Columba livia) was investigated after intravenous, intramuscular and oral administration. From the blood disappearance curves after i.v. bolus injection (10 mg/kg body weight) clearance rate, blood half-time and distribution volume were calculated. The recovery of unchanged flumequine from the droppings in 24 h was 37 +/- 10% of the administered dose. Flumequine was also given i.m. at two dose levels, 10 and 60 mg/kg body weight. The availability of flumequine as intact drug was 22 and 23%, respectively, in 24 h. Therapeutic blood levels were maintained for 4 and 10 h, respectively. After an oral dose of flumequine (60 mg/kg body weight) an availability of 6.7 +/- 2.5% and a peak blood concentration of 2.68 +/- 0.92 microgram/ml at 2 h after administration were found. The recovery of unchanged flumequine from the droppings in 24 h was 1.55 +/- 0.79% of the administered dose. With the exception of the i.m. dose of 10 mg/kg, all flumequine administrations made the pigeons vomit. It appears that blood concentrations below 3 micrograms/ml will not induce vomiting. On the basis of the present data, a dosage regimen for flumequine in pigeons of a priming dose of 30 mg/kg i.m., followed after 8 h by oral administration of 30 mg/kg, this dose being repeated every 8-12 h, would be expected to give blood concentrations between 1.44 and 2.88 micrograms/ml.

Administration, Oral↗