Sulphadimidine in the urine of experimentally fed pigs

An enzyme-linked immunoassay for the detection of sulphadimidine in unextracted pig urine is described. Twenty-four hour urine samples from six individually caged pigs, four treated and two controls, were examined during a 10-day treatment and a 12-day withdrawal period. The concentration of sulphadimidine in the urine of the treated pigs increased rapidly after feeding started and decreased on withdrawal. The maximum concentration in a control pig was 308 ng/ml, and this concentration was probably due to contamination of the environment. By the seventh day after withdrawal of the drug its concentration in the urine of the treated pigs was less than 500 ng/ml.

The effect of streptozotocin-induced diabetes on the in vivo acetylation capacity and the in vitro blood N-acetyltransferase activity of the adult male Sprague-Dawley rat

Induction of experimental diabetes using streptozotocin significantly reduced the extent of sulphamethazine acetylation by Sprague-Dawley rats. This treatment did not significantly change the total amount of sulphonomide excreted in the urine. The in vitro blood N-acetyltransferase activity of rats treated with streptozotocin was significantly higher than that of untreated animals. Increasing the in vitro glucose concentration of blood samples from both groups significantly increased the amount of acetylsulphamethazine produced.

Pantothenic acid, acute ethanol consumption and sulphadimidine acetylation

The effect of pantothenic acid and acute ethanol loading on the genetically determined N-acetyltransferase activity has been studied using sulphadimidine as a test substance. The administration of 1100 mg pantothenic acid daily (600 mg orally, 500 mg iv) for seven days did not significantly alter sulphadimidine kinetics in the primarily elderly 21 subjects we investigated. Acute ethanol loading (0.73 g/kg pure alcohol at start and 0.11 g/kg pure alcohol hourly for 8 hours afterwards, stock solution: 20% v/v ethanol in fruit juice) did not change sulphadimidine acetylation in 10 healthy male volunteers. It is concluded that despite theoretical assumptions exogenous factors like pantothenic acid and ethanol do not significantly influence the cytosolic N-acetyltransferase activity. Consequently they do not interfere with the acetylator phenotyping procedure.

Acetylation polymorphism and leprosy

The sulfones are the drug of choice in the treatment of leprosy, with dapsone as the clear favorite. The major route for dapsone metabolism leading to its inactivation and excretion is via acetylation by hepatic N-acetyl transferase (NAT), as is the case with isoniazid (INH) and sulfamethazine (SMZ). The enzyme is known to exhibit genetic polymorphism. The object of the present study is mainly to determine the incidence of acetylator phenotype in a population of leprosy patients with a view to evaluating the degree of association, if any, between phenotype and the disease. Obviously a knowledge of the incidence of the phenotypes may provide a valuable contribution to the institution of more rational and successful therapy. In the normal or control subjects, as well as in the leprosy patients, the frequency distribution histograms of the percentage acetylsulfamethazine in urine and serum samples are bimodal, and this indicates the existence of a genetic polymorphism. Based on the bimodality, individuals were classified as either "rapid" or "slow" acetylators, and the incidence of the slow acetylator phenotype of about 51% was observed in the leprosy population. This gives a relatively high incidence of the allele controlling the slow acetylator (q = 0.73). Although there is evidence that the mean percentage of SMZ acetylated in leprosy patients of the slow acetylator phenotype is significantly higher than that observed for the same phenotype in the controls (t = 4.86, P less than 0.02), statistical analyses show that there is no association between the slow acetylator phenotype and the disease.(ABSTRACT TRUNCATED AT 250 WORDS)

N-acetylation phenotyping with sulphadimidine in a Turkish population

The distribution of acetylator phenotypes was studied in 244 unrelated Turkish subjects. Sulphadimidine and its acetylated metabolite were measured in 6 h plasma and 0-6 h urine samples after an oral dose of 10 mg/kg. Subjects with 37.5% or less acetylsulphadimidine in plasma were regarded as slow acetylators and the others as rapid acetylators. The mean plasma concentration of acetylsulphadimidine was about 2.5-times lower in slow acetylators. Urinary excretion of total sulphadimidine (free + acetylated) was also significantly lower in slow acetylators compared to rapid acetylators. The frequency of slow acetylators was 60.7% in the population (95% confidence interval 54.3% to 66.8%). Sulphadimidine acetylation showed no variation due to sex, age, body weight or pre-existing disease.

Acetylator phenotype and congenital malformations

The hypothesis has been tested that an unusual maternal acetylator phenotype can predispose to congenital malformations in the fetus. The acetylator phenotype of normal caucasian control women and of mothers of malformed children was established by measuring urinary sulphadimidine and its acetylated metabolite. A further control group was the fathers of the malformed newborn. The malformations studied were facial-cleft, spina-bifida and congenital heart disease. The acetylator phenotype was shown not be modified by pregnancy. 49 of 100 (49%) control women were rapid acetylators. Amongst the 108 mothers of malformed babies, 56 (52.8%) were slow acetylators and 52 (47.2%) were fast acetylators, 42 out of 83 (50.5%) of the fathers of malformed were slow acetylators and 41 (49.5%) were fast acetylators. Thus, the acetylator phenotype of the mothers of malformed children is no different from the acetylator phenotype of controls.

Effect of intra-articular glucocorticoids on the disposition of sulphadimidine in chronic osteoarthritis patients

1. The disposition of sulphadimidine (15 mg kg-1 orally) was investigated in six chronic osteoarthritis patients (four slow and two fast acetylators) prior to and 4 days following intra-articular administration of glucocorticoids. 2. The mean (+/- s.e. mean) renal clearance of sulphadimidine was increased from 0.03 +/- 0.01 to 0.07 +/- 0.02 ml min-1 kg-1 (P = 0.01) following the administration of intra-articular steroid. 3. Mean metabolic clearance and volume of distribution data were similar on the two study days. However, two of the slow acetylators showed marked increases (63% and 193%) in metabolic clearance following steroid treatment.

Competitive direct enzyme-linked immunosorbent assay for detection of sulfamethazine residues in swine urine and muscle tissue

A sensitive assay for the detection of sulfamethazine in swine urine and muscle tissue using a direct competitive enzyme-linked immunosorbent assay (ELISA) has been developed. Undiluted urine or a phosphate-buffered saline extract of pork muscle tissue is mixed with an enzyme-labeled conjugate of sulfamethazine and horseradish peroxidase. The mixture is added to wells of a microtiter plate coated with antibody to sulfamethazine. After the test system is incubated, washed, and re-incubated with substrate and the reaction is stopped, the absorbance is measured at 405 nm. Levels of sulfamethazine as low as 20 ng sulfamethazine/g muscle tissue and 10 ng sulfamethazine/mL swine urine were detected and estimated.

The effect of food deprivation on the rate of sulfamethazine elimination in goats

The disposition kinetics and cumulative urinary excretion of sulfamethazine were compared in goats fed normally (control) and following a 72-hour period of starvation (fasting). The only pharmacokinetic parameter which showed a statistically significant difference between the two groups was the body (systemic) clearance. This decreased from 2.26 +/- 0.28 ml/min.kg (means +/- SD, n = 6) in the control group to 1.16 +/- 0.54 ml/min.kg in the fasting group (p less than 0.01). Since the apparent volume of distribution was not affected by starvation, the decreased clearance was attributed to slower metabolism of the drug. Because of the analytical method used to measure sulfamethazine concentrations in plasma and urine, no conclusion could be drawn as to whether the rates of hydroxylation or of acetylation, or both metabolic pathways were decreased in the starved condition.

N1-glucosides as urinary metabolites of sulphadimidine, sulphamerazine and sulphamethoxazole

The synthesis and characterisation of the N1-beta-D-glucosides of the three title sulphonamides are described, and these conjugates are shown, by means of HPLC and MS, to be minor urinary metabolites of these drugs.

Comparison between serum isonicotinic acid hydrazide (INH) levels and urinary sulfadimidine (sulfamethazine) acetylation as predictors of INH acetylator status

The acetylator status of 40 children with pulmonary tuberculosis was investigated by (1) sulfadimidine (SDM; sulfamethazine) acetylation test in urine and (2) estimation of isonicotinic acid hydrazide (INH) levels. The antimode was at 70% based on the frequency distribution of SDM acetylation. Children acetylating less than 70% of administered SDM were taken as slow acetylators while those with more than 70% as rapid acetylators. The serum INH antimode was at 0.85 micrograms/ml. Thus serum values less than 0.85 micrograms/ml categorised a child as rapid and those with more than 0.85 micrograms/ml as slow acetylators. The sensitivity of these two methods was similar with a correlation coefficient r = 0.64. Thus the determination of the type of acetylator by SDM acetylation test is equally reliable and technically simpler and is recommended instead of INH serum concentration.

Polymorphic acetylation of sulphamethazine in a Zimbabwe population

Sulphamethazine, 8 mg/kg body weight, was administered orally in tablet form to 100 healthy volunteers and total and free sulphamethazine were determined in the six hour urine sample. The bimodal population frequency distribution for percentage acetylated sulphamethazine showed 42 of the tested population to be fast and 58 to be slow acetylators, that is, an estimation of q = 0.72 +/- 0.3 as the frequency of the allele controlling slow acetylation. The study also revealed ample evidence that the assay of the drug in urine can be done in a significantly shorter time.

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.

Pharmacokinetics, metabolism, and renal excretion of sulfadimidine and its N4-acetyl and hydroxy metabolites in humans

Sulfadimidine is acetylated and hydroxylated in humans. The hydroxylation pathways account for 10-20% of the dose, leaving the acetylation as the major metabolic pathway. The hydroxylation pathways are independent of the acetylator phenotype. The plasma concentration-time curve of sulfadimidine in fast acetylators is biphasic, with half-lives of 1.7 and 5.4 h, whereas that in slow acetylators is monophasic, with a half-life of 7.6 h. Hydroxylation of a methyl group in sulfadimidine lowers the protein binding from 90 to 60%, while acetylation does not affect the protein binding. Methyl hydroxylation markedly increases the renal clearance.

Acetylator phenotype among individuals with glucose 6-phosphate dehydrogenase variants

The acetylator phenotype was determined for 142 Nigerian adults by administering sulphamethazine (40 mg/kg body wt) and analysing six hour urines for free and acetylated drug. Of these 142 subjects, 21 (14.8%) had no red cell glucose 6-phosphate dehydrogenase activity, 35 (24.6%) had partial activity and 86 (60.56%) had normal activity. The percentage of slow acetylators among the three groups was 38.1%, 40% and 40.7% respectively. The differences between the three groups were not statistically significant. However, individuals with no red cell glucose 6-phosphate dehydrogenase activity and who are also slow acetylators may be more sensitive to the effects of drugs like sulphamethazine, dapsone and isoniazid.

Pharmacokinetics, renal clearance, tissue distribution, and residue aspects of sulphadimidine and its N4-acetyl metabolite in pigs

Pharmacokinetics and tissue distribution experiments were conducted in pigs to which sulphadimidine (SDM) was administered intravenously, orally, and intramuscularly at a dosage of 20 mg SDM/kg. SDM was acetylated extensively, but neither hydroxy metabolites nor their derivatives could be detected in plasma, edible tissues or urine. Following i.v. and two oral routes of administration, the N4-acetylsulphadimidine (N4-SDM) concentration-time curve runs parallel to that of SDM. The percentage of N4-SDM in plasma was in the range between 7 and 13.5% of the total sulphonamide concentration. The bioavailability of SDM administered in a drench was 88.9 +/- 5.4% and administered mixed with pelleted feed for 3 consecutive days it was 48.0 +/- 11.5%. The renal clearance of unbound SDM, which was urine flow related, was 1/7 of that of creatinine, indicating reabsorption of the parent drug. The unbound N4-SDM was eliminated three times faster than creatinine, indicating that tubular secretion was the predominant mechanism of excretion. After i.v. administration, 51.9% of the administered dose was recovered in urine within 72 h p.i., one quarter of which as SDM and three quarters as N4-SDM. Tissue distribution data obtained at 26, 74, 168, and 218 h after i.m. injection revealed that the highest SDM concentration was found in plasma. The SDM concentration in muscle, liver, and kidney ranged from one third to one fifth of that in plasma. The N4-SDM formed a minor part of the sulphonamide content in edible tissues, in which the SDM as well as the N4-SDM concentration parallelled the plasma concentrations. Negative results obtained with a semi-quantitative bioassay method, based on monitoring of urine or plasma, revealed that the SDM concentration levels in edible tissues were in that case below 0.1 mu/g tissue.

Depletion kinetics of 14C-sulfamethazine [4-amino-N-(4, 6-dimethyl-2-pyrimidinyl)benzene[U-14C]sulfonamide] metabolism in swine

Swine weighing 60-70 kg were orally administered 14C-sulfamethazine [4-amino-N-(4,6-dimethyl-2-pyrimidinyl)benzene[U-14C]sulfonamide] at 12-hr intervals for 7 days (165 mg/dose; 0.126-5.04 mCi/mmol). The animals were sacrificed at 8 hr or 2, 5, or 10 days after the last dose was given and tissues were assayed for total 14C activity. The presence of 14C-labeled sulfamethazine, N4-acetylsulfamethazine, desaminosulfamethazine, and the N4-glucose conjugate of sulfamethazine in blood, liver, kidney, skeletal muscle, and adipose tissue was verified by HPLC and GC-MS analysis. Total 14C residue levels in all tissues examined had dropped to less than 0.1 ppm sulfamethazine equivalents by day 10 of the depletion period. The mean half-life (t1/2) for sulfamethazine, the N4-glucose conjugate of sulfamethazine, and N4-acetylsulfamethazine was estimated to be 0.8 day. In some tissues, the depletion of the N4-glucose conjugate of sulfamethazine and N4-acetylsulfamethazine had decreased significantly between days 5 and 10, resulting in an approximate doubling of the t1/2 for that period. In contrast, the half-life of desaminosulfamethazine varied from a mean of 0.96 day during the 8-hr-5-day depletion period to 3.7-9.1 days during the 5- 10-day depletion period. In most tissues, the t1/2 for the 14C-activity in the methanol-insoluble fraction increased by 3-5-fold between days 5 and 10 of the depletion period. No predictable relationship was observed between blood sulfamethazine or metabolite levels and total residue levels in the tissues.

Effect of concomitant isoniazid administration on determination of acetylator phenotype by sulphadimidine

The influence of concomitant administration of isoniazid (INH) on the acetylation of sulphadimidine has been studied in 6 healthy volunteers, previously identified as having the fast acetylator phenotype. INH was administered in a slow release form (500 mg tablet) 1 hour before the sulphadimidine. Acetylation of sulphadimidine was measured in plasma 6 h after its intake and in urine collected between 5 and 6 hours. INH significantly decreased the acetylated fraction of sulphadimidine in plasma from 69.0 to 54.0 and in urine from 85.9 to 81.2%. This was reflected in a significantly higher plasma concentration of unconjugated sulphadimidine and reduced urinary excretion of acetylated sulphadimidine. It is concluded that concomitant administration of INH inhibits acetylation of sulphadimidine. Fast acetylators at the border line of discrimination, may be misclassified if phenotyped with sulphadimidine during concomitant administration of INH.

Effect of exercise on plasma levels and urinary excretion of sulphadimidine and procainamide

The pharmacokinetics of sulphadimidine (n = 9) and procainamide (n = 8), drugs which showed typical polymorphic acetylation rate, were studied in healthy volunteers subjected to intense physical exercise and bed rest for 4 hours in a cross-over manner. The exercise and the rest began 3 hours after giving procainamide and 4 hours after the administration of sulphadimidine, when the drug absorption had subsided. In rapid acetylators, the exercise raised both acetylated and non-acetylated sulphadimidine concentrations in serum, compared to rest values. With procainamide the rise was insignificant. In slow acetylators, the exercise revealed a significant difference in the procainamide group but not in sulphadimidine group. The exercise did not influence the acetylation degree of either of the drugs. Neither did it affect the protein binding of sulphadimidine. The urinary excretions of procainamide and acetylprocainamide were reduced by exercise generally more than those of sulphadimidine and acetylsulphadimidine. Endogenous creatinine clearance was reduced to 66%, whereas the renal clearances of sulphadimidine, acetylsulphadimidine and procainamide decreased to 89%, 48% and 16%, respectively. The results agree with our previous findings that physical stress can result in increased serum drug levels. Exercise does not seem to change the acetylation rate nor the protein binding of drugs, but it suppresses their excretion in urine, occasionally even more than what would be expected on the basis of the decrease in the glomerular filtration rate.

Identification and quantitation of sulfamethazine metabolites by liquid chromatography and gas chromatography-mass spectrometry

Methods for the identification and quantitation of carbon-14 labeled sulfamethazine [4-amino-N-(4,6-dimethyl-2-pyrimidinyl)benzenesulfonamide], N4-acetylsulfamethazine, the N4-glucose conjugate of sulfamethazine, and desaminosulfamethazine in swine tissue are described. Tissues are ground and extracted with methanol, and the 14C-labeled compounds are purified by XAD-2 column chromatography and C-18 reverse phase liquid chromatography (LC) and the 14C-labeled compounds are then methylated and identified by gas chromatography-mass spectrometry analysis. Quantitation is accomplished by measuring the amount of 14C-activity that cochromatographs (C-18 reverse phase LC) with reference compounds.

Drug acetylation and expression of lupus erythematosus

Acetylator phenotype was measure in 58 patients presenting to a skin clinic with discoid lupus erythematosus (DLE) and in 51 normal healthy subjects. Twenty seven of the patients with DLE were found to have evidence of systemic lupus erythematosus (D+SLE). Frequency of slow acetylator phenotype was 58% in all DLE patients, 52% in those with D+SLE and was no different from the 57% in controls. The distribution of acetylator phenotypes within the groups with DLE and those with D+SLE was similar to controls. Severity of DLE was assessed as number of skin lesions and median lesion count was 11.5 in slow acetylators and 10 in fast acetylators but in D+SLE median lesion count was 22 in slow acetylators and 12 in fast acetylators, and there was a significant inverse relationship between lesion count and rate of acetylation; scores for systemic involvement showed no relationship. We conclude that there is no difference in the frequency or distribution of slow acetylator phenotype between normal subjects and patients with DLE with or without SLE but that actual rate of acetylation may determine severity of expression of the disease in slow acetylators.

Correlation of sulphadimidine acetylation test in urine and blood for isoniazid phenotyping

Sulphadimidine acetylation was determined in 110 cases in samples obtained from urine and blood. A trimodal distribution was observed by both the methods. The correlation co-efficient "r" for the two methods was 0.46.

Pharmacokinetics of sulfamethazine in male, female and castrated male swine

The concentration of sulfamethazine in plasma and sulfamethazine and its metabolites in urine were compared in male, female and castrated male swine. A surgical technique for placement of catheters in the urinary bladder was used to facilitate the collection of urine in males and castrated males. The elimination rate of sulfamethazine from plasma and the excretion of parent drug and metabolites into urine did not differ significantly among females, males and castrated male swine.