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Biomedical subjects

D Overbosch

Publications and source records attributed to D Overbosch.

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

Familial varices of the colon.

Two patients from the same family with varices throughout the entire colon and no apparent portal hypertension, are described. One patient experienced profuse bleeding after polypectomy, the other had recurrent rectal blood loss.

Aged↗
PubMed1988

The effect of probenecid on the renal tubular excretion of benzylpenicillin.

1 The aim of this study was to establish whether the renal tubular excretion of benzylpenicillin is saturable and whether the effect of probenecid on the tubular excretion of benzylpenicillin is dose-dependent. 2 Each of four volunteers underwent three experiments. In each experiment benzylpenicillin was administered by continuous infusion, such that three different consecutive concentration levels were reached. In the first experiment no probenecid was given; in the second and third experiments, probenecid was administered by continuous infusion at a low and higher rate, respectively. 3 Plasma and urinary concentrations of benzylpenicillin were determined at 30 min intervals by high performance liquid chromatography. 4 By fitting the equation Rtub = Rtub,max.Cp/(EC50 + Cp) to the values of the tubular excretion rate found for benzylpenicillin (Rtub) vs the free plasma concentration (Cp), the values of Rtub,max and EC50 could be calculated: 3350 (+/- 606) mg h-1 for Rtub,max and 48.0 (+/- 17.8) mg l-1 for EC50 (in the absence of probenecid). 5 The EC50 for benzylpenicillin increased significantly with increasing doses of probenecid. 6 The dose of probenecid at which 50% of the excretory system is occupied by probenecid in the absence of benzylpenicillin (ED50) ranged from 13.2 to 108.5 mg h-1. 7 The EC50 of probenecid in one subject could actually be measured: 52.3 mg l-1. 8 Extrapolating these results to the clinical situation, the commonly used daily dose of 2 g of probenecid is likely to be close to the maximal effective dose for inhibition of the tubular excretion of benzylpenicillin.

Adult↗
PubMed1987

Penetration of praziquantel into cerebrospinal fluid and cysticerci in human cysticercosis.

Two patients with cysticercosis received praziquantel (PZQ) 75 mg/kg/day orally together with 30 mg prednisone daily for 3 weeks. The first patient presented with grand-mal seizures, a pyramidal tract syndrome and subcutaneous cysticerci, and the other had internal hydrocephalus necessitating drainage. Serial plasma samples were taken after the first dose of PZQ. Lumbar CSF was obtained from the first patient and ventricular CSF from the second. Subcutaneous cysticerci were removed from the first patient. PZQ in the specimens was assayed by GLC. For distribution between plasma and CSF a rate constant of 4.9 h-1 for free PZQ, corresponding to a t1/2 of 8 min or less for the non-protein bound fraction was calculated for Patient 1. In the second patient the distribution was so rapid that the rate constant could not be calculated. The difference in distribution rate might have been due to use of different sampling times or to a time lag in the entry of PZQ between the ventricles and the lumbar sac. The rate constant for distribution of the drug between plasma and parasites was 1.4 h-1, corresponding to a t1/2 of 30 min or less. Thus PZQ penetrates rapidly into the CSF. It enters the parasite more slowly, although still more rapidly than the plasma half-life of PZQ (1-1 1/2 h).

Adult↗
PubMed1986

Seizures associated with oxamniquine therapy.

Three patients who were treated for schistosomiasis mansoni with oxamniquine suffered generalized seizures. We suggest that this side effect may be more common than previously reported. Specific ethnic groups may be particularly at risk.

Adult↗
PubMed1985

Comparative pharmacodynamics and clinical pharmacokinetics of phenoxymethylpenicillin and pheneticillin.

In this study the antimicrobial effects of phenoxymethylpenicillin (PM) and pheneticillin (PE) in vitro and in an experimental animal infection model were compared as well as the pharmacokinetic properties of both drugs in patients. For the inhibitory effect of PM on short-term (3 h) growth of S. aureus in vitro, this drug was 2.13 times more potent than PE. The protein binding of both drugs was similar (78-80%). The potency ratio of PM to PE against S. aureus in an experimental mouse-thigh infection was only 1.25 to 1. This is explained by the difference in the AUC after subcutaneous administration of PM (0.47 mg 1(-1) h) and PE (0.92 mg 1(-1) h). The plasma clearance after intravenous administration of PM was 476.4 ml/min and that of PE was 295.1 ml/min; the plasma clearance of both drugs was strongly correlated with the creatinine clearance. The volume of distribution in the steady state of PM was 35.41 and that of PE 22.51. In 10 patients, the absorption after oral administration of PM as the acid was 48% and that of the potassium salt of PE was 86% of the dose. From the present results it can be concluded that a difference in effectiveness of different formulations of PM and PE would depend entirely on differences in absorption.

Adult↗
PubMed1985

Renal clearance of temocillin in volunteers.

After administration of a loading dose, temocillin was infused intravenously into 5 volunteers for 3 hours (250 and 750 mg/h). A urine flow of more than 500 ml/h was maintained. The mean plasma concentrations were 131.4 and 220.7 mg/L during the lower dose and higher dose infusions, respectively, and protein binding decreased from 83% to 74% with this increase in plasma concentration. The renal clearance of the total drug increased from 29.0 ml/min (low dose) to 50.5 ml/min (high dose) [p less than 0.001], but after correction for protein binding the renal clearance of the unbound drug only increased from 169.1 to 197.0 ml/min (not statistically significant). The extrarenal clearance of temocillin was negligible. Blocking of tubular excretion by probenecid caused a maximum decrease of the renal clearance of temocillin from 34.1 to 22.4 ml/min. This maximum effect of 12.3 ml/min subsided by 1.7 ml/min/h. The renal clearance of the free drug decreased to 134.6 ml/min, slightly less than the creatinine clearance (158.1 ml/min). It may be concluded that even at high plasma concentrations of temocillin there is no saturation of the tubular transport mechanism, and that tubular excretion plays a relatively minor role in the renal excretion of the drug.

Adult↗
PubMed1985

Parasitic rheumatism presenting as oligoarthritis. A case report.

A 50-year-old Vietnamese boat refugee presented with an oligoarthritis which had been present for the two years since her arrival in The Netherlands. Her medical history was unremarkable but a peripheral eosinophilia of 20% prompted investigations leading to the isolation of Strongyloides stercoralis from the faeces. The clinical picture resolved completely after therapy with thiabendazole.

Arthritis, Infectious↗
PubMed1984

Chloroquine-resistant falciparum malaria from Malawi.

A case of falciparum malaria from Malawi is reported. RII resistance to chloroquine according to WHO standards is proven. This is the first case of chloroquine-resistance, assessed according to WHO standards, reported from Malawi.

Adult↗
PubMed1984

Malaria chemoprophylaxis for multiple drug resistant Plasmodium falciparum in Africa: an increasing problem.

Resistance of P. falciparum to the two groups of antimalaria drugs commonly used for prophylaxis, i.e. folate antagonists and 4-aminoquinolines has become a matter of great concern, also in Africa. After 1978, P. falciparum developed resistance to the group of 4-aminoquinolines, which was first reported from East Africa. Chloroquine resistant infections are now spreading into Central Africa. Similar developments are now appearing with the combination sulfadoxine/pyrimethamine. With the increasing reports of multiple drug resistance in P. falciparum from Africa, no single drug or combination of drugs in use for chemoprophylaxis can give a complete protection under all circumstances any longer. Until new effective drugs become available, it is advised to use the combination of chloroquine or amodiaquine and proguanil; the traveller should be prepared for action in the event of a breakthrough. A written instruction is suggested to be inserted in the "International Certificate of Vaccination".

Adult↗