Combination therapies that inhibit cyclooxygenase-2 and leukotriene synthesis prevent disease in murine collagen induced arthritis.

OBJECTIVE AND DESIGN: To determine the effect of combinations of cyclooxygenase (COX) inhibitors and inhibitors of leukotriene (LT) syntheses on collagen induced arthritis (CIA) in mice. METHODS: The CIA model was evaluated for the presence of eicosanoids in the paw tissue. Several selective cyclooxygenase 2 (COX-2) inhibitors or non-selective non-steroidal anti inflammatory drugs (NSAIDs) were evaluated alone or in combination with leukotriene (LT) synthesis inhibitors in the CIA model. RESULTS: Arthritic paw tissue showed increased levels of prostaglandins and leukotrienes in comparison to normal paws. Analysis of mRNA levels indicated the inducible form of the COX-2 enzyme to be the source of prostaglandins. NSAIDs, COX-2 or leukotriene synthesis inhibitors administered alone in CIA decreased severity but had little effect on disease incidence. However, the combination of selective COX-2 inhibitors with leukotriene synthesis inhibitors produced significant decreases in both incidence and severity, suggesting an additive or synergistic effect. This effect was reversible with removal of drug. Little decrease in incidence was observed with the NSAID/5-LO inhibitor combinations. CONCLUSIONS: These results suggest that the induction of the disease in CIA is mediated by products of the COX-2 enzyme and LTB4 production, and that blockade of both pathways is required to prevent CIA.

St John's Wort: effect on CYP3A4 activity.

BACKGROUND: St John's Wort is a widely used herbal product. Information regarding its potential for drug interactions is required for responsible treatment of patients using St John's Wort. CYP3A4 is a metabolic enzyme implicated in most clinically significant drug-drug interactions. OBJECTIVE: To determine the in vivo effect of reagent-grade St John's Wort extract on CYP3A4 activity through evaluation of urinary 6-beta-hydroxycortisol/cortisol ratios. METHODS: Thirteen subjects ranging in age from 18 to 25 years participated in this unblinded, multiple-dose, single-treatment before-after trial conducted in a university-based pharmacokinetics and biopharmaceutics laboratory. Each subject ingested a 300-mg tablet of reagent-grade St John's Wort extract standardized to 0.3% hypericin three times a day for 14 days. Baseline and posttreatment CYP3A4 activity was assessed with the urinary 6-beta-hydroxycortisol/cortisol ratio after a 24-hour urine collection. RESULTS: The mean +/- SD urinary 6-beta-hydroxycortisol/cortisol ratio significantly increased (P = .003) from a baseline value of 7.1 +/- 4.5 to 13 +/- 4.9. The mean +/- SD percentage increase was 114% +/- 95%, with a range from -25% to 259%. All but one subject had an increase in the ratio. CONCLUSIONS: Treatment with St John's Wort for 14 days resulted in significant increases in the urinary 6-beta-hydroxycortisol/cortisol ratio. This finding suggests that St John's Wort is an inducer of CYP3A4.

Selective inhibition of cyclooxygenase (COX)-2 reverses inflammation and expression of COX-2 and interleukin 6 in rat adjuvant arthritis.

Prostaglandins formed by the cyclooxygenase (COX) enzymes are important mediators of inflammation in arthritis. The contribution of the inducible COX-2 enzyme to inflammation in rat adjuvant arthritis was evaluated by characterization of COX-2 expression in normal and arthritic paws and by pharmacological inhibition of COX-2 activity. The injection of adjuvant induced a marked edema of the hind footpads with coincident local production of PGE2. PG production was associated with upregulation of COX-2 mRNA and protein in the affected paws. In contrast, the level of COX-1 mRNA was unaffected by adjuvant injection. TNF-alpha and IL-6 mRNAs were also increased in the inflamed paws as was IL-6 protein in the serum. Therapeutic administration of a selective COX-2 inhibitor, SC-58125, rapidly reversed paw edema and reduced the level of PGE2 in paw tissue to baseline. Interestingly, treatment with the COX-2 inhibitor also reduced the expression of COX-2 mRNA and protein in the paw. Serum IL-6 and paw IL-6 mRNA levels were also reduced to near normal levels by SC-58125. Furthermore, inhibition of COX-2 resulted in a reduction of the inflammatory cell infiltrate and decreased inflammation of the synovium. Notably, the antiinflammatory effects of SC-58125 were indistinguishable from the effects observed for indomethacin. These results suggest that COX-2 plays a prominent role in the inflammation associated with adjuvant arthritis and that COX-2 derived PGs upregulate COX-2 and IL-6 expression at inflammatory sites.

Novel terphenyls as selective cyclooxygenase-2 inhibitors and orally active anti-inflammatory agents.

A novel series of terphenyl methyl sulfones and sulfonamides have been shown to be highly potent and selective cyclooxygenase-2 (COX-2) inhibitors. The sulfonamide analogs 17 and 21 were found to be much more potent COX-2 inhibitors and orally active anti-inflammatory agents than the corresponding methyl sulfone analogs 16 and 20, respectively, albeit with some decrease in COX-2 selectivity. Structure-activity relationship studies have determined that incorporation of two fluorine atoms in the central phenyl group, as in 20 and 21, is extremely advantageous for both in vitro COX-2 potency and selectivity as well as in vivo activity. Several noticeable examples in the 1,2-diaryl-4,5-difluorobenzenesulfonamide series are 21a-c,k,l,n (COX-2, IC50 = 0.002-0.004 microM), in which all have in vitro COX-1/COX-2 selectivity > 1000. In addition, sulfonamides 21a,b,d,g,j,m,n,q were shown to have greatly enhanced oral activity with more than 90% inhibition of prostaglandin E2 production in the air pouch model of inflammation. Furthermore, sulfonamide 21b was found to be very active in the rat adjuvant-induced arthritis model (ED50 = 0.05 mg/kg) and carrageenan-induced hyperalgesia assay (ED50 = 38.7 mg/kg) with no indication of gastrointestinal toxicity in rats at doses as high as 200 mg/kg.

Evaluation of the effect of fluoxetine on the formation of carbamazepine epoxide.

Fluoxetine has been reported to increase carbamazepine (CBZ) plasma concentrations and cause adverse effects. CBZ-10, 11 epoxide (CBZE), the major metabolite of CBZ, contributes to the clinical effect and toxicity of CBZ. The objective of the present study was to investigate the effect of fluoxetine and its major metabolite, norfluoxetine, on CBZE formation in isolated perfused rat liver, in vitro human liver (n = 5) microsomes, and patients (n = 14), after either CBZ monotherapy or polytherapy with fluoxetine. In isolated perfused rat liver, there was no effect of fluoxetine (n = 8) or norfluoxetine (n = 6) on the formation clearance of CBZE (12.8 +/- 5.3 and 11.7 +/- 3.8 ml/min, respectively) or the intrinsic metabolic clearance of CBZ (6.6 +/- 2.7 and 6.3 +/- 1.8 ml/min, respectively). Studies on human liver microsomes confirmed that neither fluoxetine or norfluoxetine inhibited formation of CBZE until concentrations were > 20 times those found clinically. In support of this, there was no difference in the ratio of CBZE to CBZ plasma concentrations in patients also receiving fluoxetine when compared to patients on CBZ monotherapy; however, there was a trend toward a decrease in the apparent plasma clearance of CBZ. In conclusion, increased plasma concentrations of CBZ found when fluoxetine is added are not due to decreased formation of CBZE. Clinically, if fluoxetine causes an increase in CBZ levels, CBZE plasma concentrations will increase proportionately and contribute to the toxicity.

An investigation into the effects of oral iron supplementation on in vivo Hemoccult stool testing.

This prospective, randomized, double-blind, crossover study examined the effects of oral iron ingestion on fecal occult blood testing. One hundred healthy and asymptomatic volunteers collected stool samples after 2-wk courses of both oral iron (either ferrous sulfate or ferrous gluconate) and placebo, while following strict medicinal, dietary, and collection instructions. Each sample was tested by both the Hemoccult II and Hemoccult Sensa methods. Of the participants who completed this study (n = 78), there were no positive results for occult blood after iron ingestion when tested by either method. Only one participant displayed a positive result while taking the placebo, with this specimen considered contaminated by unexpected menses. From these findings, it can be concluded that oral iron supplementation does not cause false-positive results when the Hemoccult II or Hemoccult Sensa method is used for fecal occult blood testing.

Clinical and laboratory evaluation of cefoperazone.

Cefoperazone, a third-generation cephalosporin derivative, has been reported to have excellent antibacterial activity against a wide range of gram-positive and gram-negative pathogens, including Pseudomonas aeruginosa. We treated 54 patients with a variety of clinical infections with cefoperazone and determined the susceptibilities of their 90 bacterial isolates. An additional 25 aerobic isolates obtained from patients treated with cefamandole in a comparison study were also tested for susceptibility to cefoperazone. Thus a total of 115 isolates were studied in vitro. One hundred nine (95%) of 115 bacterial isolates, including gram-positive and gram-negative aerobes and anaerobes, were susceptible to less than or equal to 32 microgram/ml. Only four isolates (three Escherichia coli and one Serratia marcescens) were highly resistant (minimal inhibitory concentration greater than or equal to 128 microgram/ml). We were able to assess clinical outcome of cefoperazone therapy in 53 patients; favorable responses (cure of improvement) were found in 48 (91%). P. aeruginosa was a major pathogen in three patients treated with cefoperazone; all three showed a favorable response. Side effects of cefoperazone therapy were noted in seven (13%) patients, and laboratory abnormalities were observed in 11 (20%) patients; all of these were mild and readily reversible. Cefoperazone thus appears to be safe, well tolerated, and suitable for use in a variety of human infections.