The effects of an orally administered probiotic on sulfasalazine metabolism in individuals with rheumatoid arthritis: a preliminary study.

AIM: To carry out a pilot study to investigate the effect of short-term oral probiotic administration on the metabolism of sulfasalazine (SSZ) in patients with rheumatoid arthritis (RA) stabilized on SSZ. METHODS: Twelve subjects with RA taking stable doses of SSZ for a minimum of 3 months prior to the study, received a probiotic preparation contained three strains of bacteria (1.8 x 10(9) CFU/day) twice daily for 1 week. Single point blood and 12-h urine samples were taken before and after probiotic treatment and 3 weeks following discontinuation of probiotics, for determination of SSZ and its metabolites. The presence of the probiotic bacteria in the feces of patients was investigated by denaturing gradient gel electrophoresis (DGGE). RESULTS: Adverse events recorded were three instances of gastrointestinal disturbance and one flare of RA. Plasma and urinary levels of SSZ and its metabolites showed no statistically significant changes after probiotic administration and the incidence of gastrointestinal disturbance did not appear to be ascribed to higher sulfapyridine plasma levels. Probiotic-specific DGGE bands were detected in the feces of some patients after the treatment period. CONCLUSIONS: Short-term treatment of RA patients with a multi-strain probiotic did not significantly influence SSZ metabolism as has been demonstrated in animal models.

N-acetyltransferase 2 genotype-related sulfapyridine acetylation and its adverse events.

Sulfapyridine (SP), one of the metabolites of sulfasalazine (SASP), is further metabolized into N-acetylsulfapyridine (AcSP) by polymorphic N-acetyltransferase 2 (NAT2). NAT2 activity has been diagnosed by phenotyping, that is, evaluating plasma concentrations or urinary excretions of tentatively administered test drugs for dose individualization and avoidance of serious adverse events. Herein, we investigated the relationship between NAT2 genotypes and the pharmacokinetics of SP in healthy Japanese subjects, as well as the adverse events of SASP in patients with inflammatory bowel disease (IBD). Eight healthy subjects and 13 IBD patients were classified into three groups by NAT2 genotyping; the homozygote for the wild-type allele (Rapid Types), the compound heterozygote for the wild-type and mutant alleles (Intermediate Types), and the homozygote for mutant alleles (Slow Types). A single oral dose of 40 mg/kg SASP was administered to each healthy subject, and plasma and urine samples were taken until 51 and 72 h after administration, respectively. Both the SP and AcSP concentrations in each sample were determined by the HPLC method. The NAT2 genotypes were well-correlated with the plasma concentrations or urinary excretions of SP and AcSP in 8 healthy subjects, except for one Slow Type. In patients with IBD, skin rash was seen in 3 of 6 Rapid Types and 1 of 6 Intermediate Types, consistent with the concept that hypersensitive reactions are independent of serum SP concentrations. In contrast, SASP dosing-related acute pancreatitis was found in the Slow Type patient. In this case, the NAT2 activity was diagnosed by genotyping in advance, and the medical staff could pay scrupulous attention, resulting in no serious subjective symptoms such as abdominal pain, anorexia or fever. Further investigations on the relationship between the NAT2 genotype and adverse events are required, although genotyping appeared to be a promising method to avoid such serious adverse events.

Amantadine acetylation may be effected by acetyltransferases other than NAT1 or NAT2.

Amantadine is a drug with a primary amino group, and consequently a likely candidate for metabolism by acetylation. This study assessed the possibility that a person's polymorphic (NAT2) acetylator phenotype could be used to predict the extent of amantadine acetylation. Thirty-eight normal, healthy volunteers were NAT2 acetylator phenotyped with sulfapyridine. Of the six fastest (75-86%) and six slowest (34-40%) sulfapyridine acetylators, two and three, respectively, had acetylamantadine present (18-338 microg) in the 8-h urine collection. There was no correlation between NAT2 acetylator phenotype and amantadine acetylation (p<0.5), and no difference in the total urine amantadine excreted over 8 h between acetylators and nonacetylators (28.3+/-9.7 vs. 30.4+/-9.6 mg, respectively, mean +/- SD). Acetylamantadine represented 0.1-1.5% (median 0.5%) of urinary drug content over 8 h. Our data confirm that amantadine is acetylated in humans and demonstrate for the first time that the extent is not correlated with NAT2 acetylator phenotype. Parallel in vitro enzyme studies indicate the possibility that neither NATI nor NAT2 is responsible for acetylation of amantadine.

Lack of interaction between sulphasalazine and cimetidine in patients with rheumatoid arthritis.

The interaction between sulphasalazine and cimetidine has been studied, a drug combination which is quite likely in view of the higher incidence of peptic ulceration in patients with RA. Nine patients with RA on sulphasalazine (group I) were given cimetidine 400 mg three times daily and followed up for 18 weeks. In addition, five patients on sulphasalazine alone (group II), who served as a control group, were also followed up in the same manner as group I. Monitoring included assessment of disease activity and haematological variables, and measurement of plasma and urinary levels of sulphapyridine and its metabolites. There was no significant change in either the haematological parameters or sulphapyridine pharmacokinetics upon administration of cimetidine. We therefore conclude that cimetidine may be safely used in patients with RA who are being treated with sulphasalazine.

Antifertility effects of sulfapyridine on male hamsters.

Sulfapyridine was administered to mature male golden hamsters either by impregnation in feed pellets, or by subcutaneous injection as a solution in dimethylsulfoxide. The average litter size for control males was 8.3 +/- 3.3 (n = 13) vs. 4.2 +/- 2.7 (n = 11) for sulfapyridine-fed treated animals. Histology of the testis and epididymis was normal and sperm were normal in morphology and motility. Subcutaneous injection of sulfapyridine caused much more dramatic inhibition of male fertility than was achieved by feeding the drug. Sulfapyridine (750 mg/kg body weight in 0.2 ml DMSO) injected subcutaneously for 60 days was effective in reducing testis size and sperm quality. Histology of testes showed spermatogenic arrest at young spermatids. Two classes of animals were found in both sulfapyridine-fed and -injected treatment groups. One class was relatively resistant to the antifertility effects of the drugs. This difference may reflect differing abilities of the animals to convert sulfapyridine to an active form or to excrete its metabolites.

Pharmacokinetics of sulfasalazine metabolites in rats following concomitant oral administration of riboflavin.

Sulfasalazine, 60 mg/kg, was administered orally to groups of rats (n = 4) along with 1, 5, or 10 mg/kg of riboflavin. Plasma and urine were assayed for 5-aminosalicylic acid, acetyl-5-aminosalicylic acid, sulfapyridine, and acetyl-sulfapyridine using an HPLC method. The mean percent of dose recovered as total metabolites in urine was significantly greater (alpha = 0.01) for the group receiving 10 mg/kg riboflavin compared to the controls or the group receiving 1 mg/kg riboflavin. Plasma AUC and Cmax values were also significantly greater (alpha = 0.05) for the 10 mg/kg riboflavin group. These results suggest that at higher doses, a significant fraction of riboflavin reaches the colon intact and stimulates more efficient reduction of the azo bond in sulfasalazine. Since the concentrations of 5-ASA achieved in the colon may be directly related to the efficacy of sulfasalazine in treating inflammatory bowel disease, concomitant administration of riboflavin may enhance sulfasalazine's efficacy in humans.

Influence of intestinal transit time on azo-reduction of salicylazosulphapyridine (Salazopyrin).

During a normal and an accelerated intestinal transit, in seven healthy volunteers, the recoveries of salicylazosulphapyridine (SASP) and its split products sulphapyridine (SP) and 5-aminosalicylic acid (5-ASA) were determined in urine and faeces. The azo-reduction of SASP and consequently the recovery of 5-ASA in the faeces was found to be substantially decreased during an accelerated intestinal transit. In addition, in 18 patients with inflammatory disease of the colon during maintenance therapy of SASP it could be demonstrated that the serum SP levels were related to the diarrhoeal state and did not correlate with disease activity. As recent studies have reported that 5-ASA is possibly the active therapeutic moiety of SASP, the ineffectiveness of SASP therapy in patients with active colitis may be ascribed to the reduced azo reduction of SASP as the result of profuse diarrhoea.

[The effect of phenobarbital on the acetylation of sulfapyridazine and formation of sulfadimethoxine glucronide in man]. / Bliianie fenobarbitala na atsetilirovanie sul'fapiridazina i obrazovanie Gliukuronida sul'fadimetoksina u liudei.

In the urine of 20 normal male students-volunteers aged 20 to 30 the percentage of acetylated sulphapyridazine and sulphadimetoxin was measudred 12 hours of taking by them 1.0 g of sulphanilamide. Takinpreliminarily phenobarbital (0.1 g before going to bed for 2 days) did not have any effect on the percentage of acetylated sulphapyridazine in the urine of the examined, nor did it affect the level of the free compound. Phenorbarbital was found to significantly raise the level of sulphadimetoxin from 84.3 up to 88.1 per cent in the urine, the amount of free sulphadimetoxine then declining. In experiments on isolated lenghts of the small intestine of the rat turned inside out it was shown that a coursewise introduction of phenobarbital (25 mg/kg for 5 days) did have any effect on the acetylation of sulphapyridazine.

Polymorphic acetylation of procaine amide in healthy subjects.

The acetylation of procaine amide has been studied by means of gas liquid chromatography in 33 healthy human volunteers. The acetylator phenotype was determined by measuring unchanged and acetylated sulphapyridine in urine. Slow acetylators of sulphapyridine excreted significantly less procaine amide in acetylated from in the urine than rapid acetylators (9 plus or minus 1% against 19 plus or minus 4%). Hence, it is suggested that the acetylation of procaine amide is subject to the same genetic polymorphism as that of isoniazid and some sulfonamides.