Sulindac Sulfoxide Research Articles

Comparative Bioavailability of Sulindac in Capsule and Tablet Formulations

The cyclooxygenase (COX)-2 enzyme appears to be an important target for cancer chemoprevention. Given the recent emergence of potentially serious cardiovascular toxicity associated with selective COX-2 inhibitors, nonsteroidal antiinflammatory drugs (NSAIDs), which inhibit both COX-1 and COX-2, have received renewed attention as candidate chemoprevention agents. Sulindac has shown consistent chemopreventive potential in preclinical studies as well as in a limited number of clinical trials reported to date. For the current pharmacokinetic study, sulindac capsules were prepared to facilitate ample agent supplies for future intervention studies. Encapsulation of the parent compound (sulindac sulfoxide) can be readily accomplished, but the effects of alternate formulations on bioavailability have not been rigorously examined. In the present single-dose, two-period crossover trial, we conducted pharmacokinetic analyses of sulindac in capsule (test) versus tablet (reference) formulations. Overall, bioavailability appeared to be higher for the capsule compared with the tablet formulation based on test-to-reference pharmacokinetic variable ratios for the parent compound alone. However, additional analyses based on the sulfide and sulfone metabolites of sulindac with the same pharmacokinetic variables indicated similar chemopreventive exposures between the capsule and tablet formulations. These data support the use of sulindac capsules, which can be readily prepared with matching placebos, in future blinded chemoprevention trials.

Non‐steroidal anti‐inflammatory drugs have bacteriostatic and bactericidal activity against Helicobacter pylori

Helicobacter pylori infection and non-steroidal anti-inflammatory drugs (NSAIDs) are each associated with gastrointestinal mucosal damage, but the extent and direction of their interactions remain controversial. Therefore, the purpose of the present paper was to examine whether specific NSAIDs inhibit the growth of Helicobacter pylori in vitro. Sodium salicylate, ibuprofen, indomethacin, the selective cyclooxygenase-2 inhibitor NS-398 and two derivatives of sulindac sulfoxide were tested against two laboratory strains of H. pylori, the mouse-adapted Sydney strain, and against seven fresh clinical isolates of Helicobacter pylori. Possible effects on Campylobacter jejuni, Staphyloccoccus aureus, Escherichia coli, Salmonella typhimurium, and Shigella boydii were also examined. Certain NSAIDs possess antibacterial activity against Helicobacter pylori at therapeutically achievable doses; an effect that appears to be independent of cyclooxygenase enzymes inhibition. For Helicobacter pylori, >90% growth inhibition and bactericidal activity were observed consistently for sulindac sulfide at < or =70 microg/mL and sulindac sulfone at < or =175 microg/mL. The minimal inhibitory concentration against Helicobacter pylori was 125 microg/mL for ibuprofen, 100 microg/mL for indomethacin and 300 microg/mL for NS-398 but much higher concentration of sodium salicylate (4000 microg/mL) and sulindac sulfoxide (> or =1250 microg/mL) were required to inhibit the growth of Helicobacter pylori. The decreased prevalence of Helicobacter pylori in specimens from some NSAID users and the chemopreventive effects of NSAIDs in gastric cancer may be related to inhibition of Helicobacter pylori growth.

Stereoselective sulfoxidation of sulindac sulfide by flavin-containing monooxygenases: Comparison of human liver and kidney microsomes and mammalian enzymes

The stereoselective sulfoxidation of the pharmacologically active metabolite of sulindac, sulindac sulfide, was characterized in human liver, kidney, and cDNA-expressed enzymes. Kinetic parameter estimates (pH = 7.4) for sulindac sulfoxide formation in human liver microsomes (N = 4) for R- and S-sulindac sulfoxide were V max = 1.5 ± 0.50 nmol/min/mg, K m = 15 ± 5.1 μM; and V max = 1.1 ± 0.36 nmol/min/mg, K m = 16 ± 6.1 μM, respectively. Kidney microsomes (N = 3) produced parameter estimates (pH = 7.4) of V max = 0.9 ± 0.29 nmol/min/mg, K m = 15 ± 2.9 μM; V max = 0.5 ± 0.21 nmol/min/mg, K m = 22 ± 1.9 μM for R- and S-sulindac sulfoxide, respectively. In human liver and flavin-containing monooxygenase 3 (FMO3) the V max for R-sulindac sulfoxide increased 60–70% at pH = 8.5, but for S-sulindac sulfoxide was unchanged. In fourteen liver microsomal preparations, significant correlations occurred between R-sulindac sulfoxide formation and either immunoquantified FMO or nicotine N-oxidation ( r = 0.88 and 0.83; P < 0.01). The R- and S-sulindac sulfoxide formation rate also correlated significantly ( r = 0.85 and 0.75; P < 0.01) with immunoquantified FMO in thirteen kidney microsomal samples. Mild heat deactivation of microsomes reduced activity by 30–60%, and a loss in stereoselectivity was observed. Methimazole was a potent and nonstereoselective inhibitor of sulfoxidation in liver and kidney microsomes. n-Octylamine and membrane solubilization with lubrol were potent and selective inhibitors of S-sulindac sulfoxide formation. cDNA-expressed CYPs failed to appreciably sulfoxidate sulindac sulfide, and CYP inhibitors were ineffective in suppressing catalytic activity. Purified mini-pig liver FMO1, rabbit lung FMO2, and human cDNA-expressed FMO3 efficiently oxidized sulindac sulfide with a high degree of stereoselectivity towards the R-isomer, but FMO5 lacked catalytic activity. The biotransformation of the sulfide to the sulfoxide is catalyzed predominately by FMOs and may prove to be useful in characterizing FMO activity.

Sulindac Sulfide, but Not Sulindac Sulfone, Inhibits Colorectal Cancer Growth

Sulindac sulfide, a metabolite of the nonsteroidal antiinflammatory drug (NSAID) sulindac sulfoxide, is effective at reducing tumor burden in both familial adenomatous polyposis patients and in animals with colorectal cancer. Another sulindac sulfoxide metabolite, sulindac sulfone, has been reported to have antitumor properties without inhibiting cyclooxygenase activity. Here we report the effect of sulindac sulfone treatment on the growth of colorectal carcinoma cells. We observed that sulindac sulfide or sulfone treatment of HCA-7 cells led to inhibition of prostaglandin E2 production. Both sulindac sulfide and sulfone inhibited HCA-7 and HCT-116 cell growth in vitro. Sulindac sulfone had no effect on the growth of either HCA-7 or HCT-116 xenografts, whereas the sulfide derivative inhibited HCA-7 growth in vivo. Both sulindac sulfide and sulfone inhibited colon carcinoma cell growth and prostaglandin production in vitro, but sulindac sulfone had no effect on the growth of colon cancer cell xenografts in nude mice.

Effect of sulindac on prostaglandin synthesis in human and in cultured rat renal and vascular smooth muscle cells.

To examine the hypothesis that sulindac does not inhibit renal prostaglandin (PG) synthesis, we investigated the effects of sulindac and other nonsteroidal anti-inflammatory drugs on PG synthesis in human and in cultured rat renal and vascular smooth muscle (VSM) cells. In 7 patients with chronic glomerular disease, creatinine clearance and proteinuria were not changed by sulindac but were significantly reduced by diclofenac sodium. However, urinary excretion of PGE2 was decreased by both drugs. In cultured glomerular mesangial (GM), renal papillary collecting tubule (RPCT) and VSM cells from mesenteric artery, indomethacin, tiaprofenic acid, aspirin and ibuprofen inhibited both basal and arachidonic acid (AA)-stimulated PG synthesis dose-dependently. Although sulindac sulfoxide, at the same concentrations, inhibited both basal and AA-stimulated PGE2 synthesis in RPCT cells, it was less potent to inhibit PGI2 synthesis in VSM cells or PGE2 synthesis in GM cells. Active form sulindac sulfide inhibited PG synthesis in all types of cells but its inactive form sulfone did not. We conclude that sulindac inhibits renal PG synthesis but has little effect on renal function. This may be explained by its relatively weak potency on glomerular or vascular PG synthesis inhibition possibly due to the different biotransformation of the sulfoxide to the active sulfide in these cells.

CAMP-dependent protein kinase in chondrocyte cultures: Holoenzyme activation, phosphorylation of cellular proteins, effects of NSAIDs and possible role in proteoglycan synthesis

R ECENT EVIDENCE showed that chondrocytes treated in culture with nonsteroidal antiinflammatory drugs (NSAIDs) exhibited reduced eicosanoid production, which was coupled to reduced intracellular accumulation of cyclic adenosine monophosphate (CAMP).’ Typically, NSAIDs have variable effects on cartilage proteoglycan and collagen synthesis and catabolism.2*3 Some NSAIDs are known to stimulate proteoglycan synthesis. These include sulindac sulfide4 and benoxaprofen5 However, the majority, including fenoprofen4 ibuprofen4 indomethacin,2T6*7 phenylbutazone,8 salicylates,7~9~‘0 and tolmetin,” suppress proteoglycan synthesis. Piroxicam may enhance proteolycan synthesisI or be without effect 12,13 the same can be said of the effect of tiaprdfenic acid2 and in some cases, indomethatin and sulindac sulfoxide.4 Many of these results come from studies conducted on articular cartilage explant culturesI or on cultured chondrocytes’2q’3 where a concentration range of NSAIDs can be tested readily. A recent review has appeared on this subject.” Two types of CAMP-dependent protein kinase (cAMPPk), type 1 and type 2, resolved by differential elution from diethylaminoethylcellulose (DEAE-cellulose), have been shown to

Effect of exogenous prostaglandins and nonsteroidal anti-inflammatory agents on prostaglandin secretion and proliferation of mouse embryo fibroblasts in culture

During wound healing, the positive and negative modulation of fibroblast proliferation may be due, in part, to the high prostaglandin concentration of the inflammatory exudates. In vitro, PGF 2α has been shown to stimulate, whereas PGE 2 inhibits, the growth of different fibroblast cell lines. Therefore, we have investigated the effect of exogenous prostaglandins (PGs) and of various nonsteroidal anti-inflammatory drugs (NSAIDs) on the proliferation and the prostaglandin (PG) synthesis of normal mouse embryo fibroblasts. PGF 2α, 6-keto PGF 1α and PGE 2 increase fibroblast proliferation. On the other hand, PGF 2α increases the synthesis of PGE 2 and 6-keto PGF 1α while 6-keto PGF 1α solely inhibits PGF 2α release, PGE 2 being inactive. The mouse embryo fibroblasts partially transform the prodrug sulindac sulfoxide in the sulfide form, which completely inhibits PG synthesis, as does indomethacin. In contrast, ibuprofen exerts a differential action, according to the type of PG measured. Among the NSAIDs tested, only sulindac (sulfoxide or sulfide) stimulates fibroblast proliferation and this effect appears independent of an alteration of PG synthesis. Therefore, in this model of normal mouse embryo fibroblasts, while endogenous prostaglandins are not involved in the control of cell proliferation, exogenous PGs have the ability to alter fibroblast growth and PG synthesis.

Mechanisms of the nephrotoxicity of non-steroidal anti-inflammatory drugs.

Renal cortical prostaglandin synthesis, particularly by arterioles and glomeruli, is important to preserve renal blood flow (RBF) and glomerular filtration rate (GFR). Glomeruli and arterioles synthesize not only the vasodilatory prostaglandins PGE2 and PGI2, but also the vasoconstrictor, thromboxane A2. The primary renal cortical actions of these prostaglandins are renal vasodilatation and maintenance of GFR (PGE2 and PGI2) or renal vasoconstriction and reduction of GFR (thromboxane A2). Vasodilatory renal prostaglandins are relatively unimportant under normal circumstances but play a modulatory role after ischemia or in the presence of increased concentrations of vasoconstrictor substances such as angiotensin II (ANG II), vasopressin or norepinephrine. ANG II and vasopressin stimulate the synthesis of PGE2 in rat glomerular epithelial and mesangial cells maintained in cell culture. These stimulatory actions of constrictor peptides are dependent upon calcium entry into the cells since removal of extracellular calcium or co-incubation with verapamil or nifedipine block the prostaglandin stimulatory capacity of ANG II or vasopressin. In vivo indomethacin potentiates the actions of ANG II on the kidney, particularly the reduction of RBF and GFR. Isolated rat glomeruli contract in response to ANG II and this contractile effect, which reflects reduction in glomerular filtration surface area, can be potentiated by cyclooxygenase blockade. Conversely, arachidonic acid reduces the glomerular contractile effect of ANG II. The importance of renal prostaglandins in support of RBF and GFR has been studied in dogs after chronic bile duct ligation (CBDL). CBDL dogs have significant increase in renal PGE2 and PGI2 which maintain RBF and GFR since cyclo-oxygenase inhibition resulted in a 50% decrease in both RBF and GFR. Indomethacin, ibuprofen, naproxen, and sulindac sulfide had comparable effects. The pro-drug, sulindac sulfoxide, was tested in normal volunteers and found to spare renal prostaglandin synthesis whereas indomethacin reduced renal synthesis of PGE2 and PGF2 alpha by more than 50%. In vitro, sulindac sulfide is a potent inhibitor of renal prostaglandin synthesis by kidney cells in culture. It is, therefore, concluded that renal prostaglandins play an important vasoregulatory role. Furthermore, sulindac sulfoxide may spare renal cyclo-oxygenase and thereby preserve renal function.

Effects of Sulindac on in vitro immunologic function and on prostaglandin production by human peripheral blood mononuclear leukocytes

Prostaglandins (PG) appear to regulate immune-mediated inflammation, but the mechanisms involved remain unclear. Several families of nonsteroidal antiinflammatory drugs (NSAID) have been observed to inhibit PG synthesis. Among these drugs, sulindac sulfide is a potent inhibitor of PG production while its parent pro-drug, sulindac sulfoxide (sulindac), lacks PG synthesis inhibitory activity in cell-free systems. We have studied the effects of sulindac sulfoxide on the blastogenic response of human peripheral blood mononuclear cells (PBMC) stimulated by exposure to alloantigens and mitogens in vitro. Sulindac inhibited proliferation of activated PBMC in a dose-dependent manner but had little effect on the proliferation of unstimulated cells. The inhibition of mitogen-induced blastogenesis correlated with both the uptake of radiolabeled drug and the inhibition of in vitro production of PG (PGE and PGF) by mitogen-activated PBMC. These data indicate a functional relationship between PG synthesis and immune cell activation which may also apply to PBMC activated in vivo by autoimmune disease. Metabolism of sulindac sulfoxide by PBMC in vitro produced too little sulindac sulfide to adequately explain the inhibition of PG production. These data suggest that immunomodulation by sulindac may be due to a direct inhibition of cellular activation. Thus, it is proposed that decreased PG production may be a result rather than the cause of the hypoproliferative response.

Effects of some nonsteroidal antiinflammatory drugs on proteoglycan metabolism and organization in canine articular cartilage.

The effects on proteoglycan metabolism and aggregation of several nonsteroidal antiinflammatory drugs commonly used in the treatment of arthritis were examined in cultures of normal canine articular cartilage. Fenoprofen and ibuprofen inhibited net proteoglycan synthesis in a concentration-dependent fashion. At concentrations in the culture medium comparable to plasma concentrations seen in patients after oral administration in humans, net proteoglycan synthesis in the presence of these drugs averaged 72% and 86% of the control values, respectively (P < 0.01). In contrast, indomethacin and sulindac sulfoxide had no effect on proteoglycan synthesis, while sulindac sulfide stimulated synthesis in a non-concentration dependent fashion (average, 13%). In the presence of ibuprofen or sulindac sulfide, catabolism of sulfated glycosaminoglycans was the same as that in control cartilage, while fenoprofen decreased the rate of degradation slightly. The proportion of newly synthesized proteoglycans existing as aggregates and the average hydrodynamic size of disaggregated proteoglycans were unaffected by ibuprofen, indomethacin, sulindac sulfide, or sulindac sulfoxide. Fenoprofen, on the other hand, interfered with the ability of the cartilage hyaluronic acid to interact with proteoglycans to form aggregates, whereas it had no effect on the in vitro association of proteoglycans with hyaluronic acid from umbilical cord.

The antiinflammatory activity of analogs of indomethacin correlates with their inhibitory effects on phospholipase A 2 of rabbit polymorphonuclear leukocytes

The effect of the antiinflammatory agent sulindac sulfide, a sulfated analog of indomethacin and an inhibitor of prostaglandin synthesis in vitro, on the action of partially purified rabbit polymorphonuclear leukocyte phospholipase A 2 (EC 3.1.1.4) was examined. Sulindac sulfide produces a dose-dependent inhibition of this phospholipase A 2 ( I 50 = 10 μM) that is still recognizable at 1 μM. This inhibition is of the noncompetitive type with an apparent K of 5 μM and in all aspects examined cannot be distinguished from the effects, recently reported (Kaplan, L., Weiss, J. and Elsbach, P. (1978) Proc. Natl. Acad. Sci. U.S.A. 75, 2955–2958), of indomethacin on the enzyme. In contrast, the pharmacologically inactive analogs sulindac sulfoxide and sulindac sulfone are without any inhibitory effect at 100 μM. Other antiinflammatory agents, including the steroids dexamethasone and hydrocortisone hemisuccinate, and the non-steroids acetylsalicyclic acid, sodium salicylate, sulfinpyrazone and quinacrine also do not inhibit the leukocyte phospholipase A 2 at concentrations as high as 100 μM. Meclofenamic acid and flufenamic acid are weakly inhibitory ( I 50 = 100–500 μM). The apparent specificity of the inhibition of leukocyte phospholipase A 2 by low concentrations of pharmacologically active analogs of indomethacin supports our contention that this effect may contribute to the effects of these agents on prostaglandin synthesis.