Browsing by Author "Seifart, H. I."
Now showing 1 - 3 of 3
Results Per Page
Sort Options
- ItemEndogenous immunoreactive digitalis-like substance in neonatal serum and placental extracts(Health & Medical Publishing Group, 1984) Beyers, A. D.; Spruyt, L. L.; Seifart, H. I.; Kriegler, A.; Parkin, D. P.; Van Jaarsveld, P. P.Therapeutic levels of digoxin in the serum of untreated neonates delivered to mothers who had not received the drug prenatally were detected by radio-immunoassay. Digoxin levels in neonates should be interpreted with care because of the unknown contribution by the endogenous digitalis-like substance (DLS) to the level of the drug. Three commercially available radio-immunoassay kits were compared with regard to their sensitivity and reproducibility in detecting the endogenous DLS. The kit from Clinical Assays (Cambridge, Mass., USA) was selected for further investigations. In a series of 35 paired samples of maternal and cord blood the average DLS values in terms of digoxin were 0.52 ± 0.07 and 0.81 ± 0.27 ng/ml respectively. This difference is statistically highly significant. In the case of infants with DLS values of 1-1.5 ng/ml in terms of digoxin, approximately 1 week was required to reach non-therapeutic digoxin levels, i.e. below 0.5 ng/ml. Gel chromatography showed that the DLS in neonatal serum was more closely associated with protein than is authentic digoxin. In placental extracts it followed the elution profile of the protein completely, but it shifted to fractions with a lower molecular weight than haemoglobin after trypsinization. The level of DLS in neonatal serum was also increased by more than half its original value by trypsinization. Proteolysis therefore seems to have a releasing effect on DLS. The molecular size of this substance is probably in the same range as that of polypeptides, since it was not dialysable from trypsinized and untreated samples through a membrane with a 22,000 dalton molecular weight cut-off point.
- Item'n Oorsig van die bepaling van die vroeë bakterisidiese aktiwiteit van verskeie antituberkilosemiddels(AOSIS OpenJournals, 2003) Donald, P. R.; Sirgel, F. A.; Venter, A.; Fourie, P. B.; Parkin, D. P.; Seifart, H. I.; Van de Wal, B. W.; Maritz, J. S.Die vroeë bakterisidiese aktiwiteit (VBA) van ’n antituberkulosemiddel is die daaglikse afname van M tuberculosis in log10 kolonievormende eenhede per ml sputum, tydens die eerste twee dae van behandeling met die middel. Dit weerspieël die vermoë van ’n middel om aktief metaboliserende organismes in tuberkulose-longholtes te dood. Dit is ’n relatief goedkoop metode om in ’n klein groep pasiënte die antituberkulose-aktiwiteit van ’n middel, binne maande, in vivo te evalueer. Hierdie artikel som ons ondervinding op tydens sewe gepubliseerde VBA-studies, en die bronne van variasie in die prosedure word identifiseer. Die pasiënte in hierdie studies was gemiddeld 33 jaar oud, met ’n gemiddelde gewig van 50 kg en 55% het ekstensiewe of massiewe longaantasting gehad. Die hoogste VBA-waardes (0,50-0,66) is gevind in pasiënte wat isoniasied ontvang het, en die laagste waardes (0,05 en 0,09 respektiewelik) was gevind in pasiënte wat die aminoglikosiede amikasien en paromomisien, albei in doserings van 15 mg/kg liggaamsgewig, ontvang het. Die algehele variasie in die VBA van 248 pasiënte was 0,0312, en die variasie toegeskryf aan die proses van sputumproduksie en -versameling was 0,0223. Dit blyk dat die verskillende aspekte van sputumproduksie en -versameling, betrokke by die lewering van ’n verteenwoordigende sputummonster, ’n groter bydrae maak tot variasie tydens die prosedure as die laboratoriumaspekte van die tegniek. Die keuring van pasiënte vir insluiting in VBA-studies, en hulle vermoë om saam te werk om ’n verteenwoordigende sputummonster te produseer, is van deurslaggewende belang in die suksesvolle voltooiing van VBA-studies.
- ItemThe pharmacokinetics of enteral antituberculosis drugs in patients requiring intensive care(Health and Medical Publishing Group (HMPG), 2013-06) Koegelenberg, C. F. N.; Nortje, A.; Lalla, U.; Enslin, A.; Irusen, E. M.; Rosenkranz, B.; Seifart, H. I.; Bolliger, C. T.Background. There is a paucity of data on the pharmacokinetics of fixed-dose combination enteral antituberculosis treatment in critically ill patients. Objectives. To establish the pharmacokinetic profile of a fixed-dose combination of rifampicin, isoniazid, pyrazinamide and ethambutol given according to weight via a nasogastric tube to patients admitted to an intensive care unit (ICU). Methods. We conducted a prospective, observational study on 10 patients (mean age 32 years, 6 male) admitted to an ICU and treated for tuberculosis (TB). Serum concentrations of the drugs were determined at eight predetermined intervals over 24 hours by means of highperformance liquid chromatography. Results. The therapeutic maximum plasma concentration (Cmax) for rifampicin at time to peak concentration was achieved in only 4 patients, whereas 2 did not achieve therapeutic Cmax for isoniazid. No patient reached sub-therapeutic Cmax for pyrazinamide (6 were within and 4 above therapeutic range). Three patients reached sub-therapeutic Cmax for ethambutol, and 6 patients were within and 1 above the therapeutic range. Patients with a sub-therapeutic rifampicin level had a higher mean Acute Physiology and Chronic Health Evaluation II (APACHE II) score (p=0.03) and a lower estimated glomerular filtration rate (GFR) (p=0.03). Conclusions. A fixed-dose combination tablet, crushed and mixed with water, given according to weight via a nasogastric tube to patients with TB admitted to an ICU resulted in sub-therapeutic rifampicin plasma concentrations in the majority of patients, whereas the other drugs had a more favourable pharmacokinetic profile. Patients with a sub-therapeutic rifampicin concentration had a higher APACHE II score and a lower estimated GFR, which may contribute to suboptimal outcomes in critically ill patients. Studies in other settings have reported similar proportions of patients with ‘sub-therapeutic’ rifampicin concentrations.