Phospho-NSAIDs have enhanced efficacy in mice lacking plasma carboxylesterase: implications for their clinical pharmacology

PURPOSE

The purpose of the study was to evaluate the metabolism, pharmacokinetics and efficacy of phospho-NSAIDs in Ces1c-knockout mice.

METHODS

Hydrolysis of phospho-NSAIDs by Ces1c was investigated using Ces1c-overexpressing cells. The rate of phospho-NSAID hydrolysis was compared between wild-type, Ces1c+/- and Ces1c-/- mouse plasma in vitro, and the effect of plasma Ces1c on the cytotoxicity of phospho-NSAIDs was evaluated. Pharmacokinetics of phospho-sulindac was examined in wild-type and Ces1c-/- mice. The impact of Ces1c on the efficacy of phospho-sulindac was investigated using lung and pancreatic cancer models in vivo.

RESULTS

Phospho-NSAIDs were extensively hydrolyzed in Ces1c-overexpressing cells. Phospho-NSAID hydrolysis in wild-type mouse plasma was 6-530-fold higher than that in the plasma of Ces1c-/- mice. Ces1c-expressing wild-type mouse serum attenuated the in vitro cytotoxicity of phospho-NSAIDs towards cancer cells. Pharmacokinetic studies of phospho-sulindac using wild-type and Ces1c-/- mice demonstrated 2-fold less inactivation of phospho-sulindac in the latter. Phospho-sulindac was 2-fold more efficacious in inhibiting the growth of lung and pancreatic carcinoma in Ces1c -/- mice, as compared to wild-type mice.

CONCLUSIONS

Our results indicate that intact phospho-NSAIDs are the pharmacologically active entities and phospho-NSAIDs are expected to be more efficacious in humans than in rodents due to their differential expression of carboxylesterases.

Exisulind in the treatment of prostate cancer

Prostate cancer represents the most common noncutaneous malignancy in men. With the widespread use of prostate-specific antigen screening, as many as one in six men in the USA will be diagnosed with prostate cancer. Significant healthcare resources are currently devoted to the treatment of this disease, specifically aimed at improving the side effects of successful treatment. Surgery or radiation therapy provides the best chance of cure from this disease. However, as many as 50% of patients treated with curative intent will develop a recurrence 10-15 years following treatment. Hormonal ablation via medical or surgical castration provides disease control, but is associated with significant hot flushes, loss of libido and impotence. Selective, apoptotic antineoplastic drugs, such as exisulind, may provide an alternative method to treating or preventing prostate cancer. This drug profile reviews the evidence for the use of exisulind in the treatment of prostate cancer.

Hydrogen sulfide-releasing NSAIDs inhibit the growth of human cancer cells: a general property and evidence of a tissue type-independent effect

Hydrogen sulfide-releasing non-steroidal anti-inflammatory drugs (HS-NSAIDs) are an emerging novel class of compounds with significant anti-inflammatory properties. They consist of a traditional NSAID to which an H(2)S-releasing moiety is covalently attached. We examined the effects of four different HS-NSAIDs on the growth properties of eleven different human cancer cell lines of six different tissue origins. Human colon, breast, pancreatic, prostate, lung, and leukemia cancer cell lines were treated with HS-aspirin, -sulindac, -iburofen, -naproxen, and their traditional counterparts. HS-NSAIDs inhibited the growth of all cancer cell lines studied, with potencies of 28- to >3000-fold greater than that of their traditional counterparts. HS-aspirin (HS-ASA) was consistently the most potent. HS-NSAIDs inhibited cell proliferation, induced apoptosis, and caused G(0)/G(1) cell cycle block. Metabolism of HS-ASA by colon cells showed that the acetyl group of ASA was hydrolyzed rapidly, followed by hydrolysis of the ester bond linking the salicylate anion to the H(2)S releasing moiety, producing salicylic acid and ADT-OH from which H(2)S is released. In reconstitution studies, ASA and ADT-OH were individually less active than the intact HS-ASA towards cell growth inhibition. Additionally, the combination of these two components representing a fairly close approximation to the intact HS-ASA, was 95-fold less active than the intact HS-ASA for growth inhibition. Taken together, these results demonstrate that HS-NSAIDs have potential anti-growth activity against a wide variety of human cancer cells.

Effects of oral dosing paradigms (gavage versus diet) on pharmacokinetics and pharmacodynamics

In cancer chemopreventive studies, test agents are typically administered via diet, while the preclinical safety studies normally employ oral gavage dosing. Correspondence in pharmacokinetic and pharmacodynamic profiles between the two dosing approaches cannot be assumed a priori. Sulindac, a non-steroidal anti-inflammatory agent with potential chemopreventive activity, was used to assess effects of the two oral dosing paradigms on its pharmacokinetics and pharmacodynamics. Time-dependent concentrations of sulindac and its sulfone metabolite were determined in plasma and potential target organ, mammary gland. Prostaglandin E(2) was used as a pharmacodynamic biomarker and measured in mammary gland. An inverse linear relationship was detected between pharmacodynamic and pharmacokinetic markers, area under the curve for prostaglandin E(2) levels and sulindac sulfone concentrations, respectively, in the mammary tissue. Marked differences in pharmacokinetics and pharmacodynamics were observed after administration of sulindac by the two oral dosing paradigms. In general, oral gavage resulted in higher peak and lower trough concentrations of sulindac in plasma and mammary tissue, higher area under concentration-time curve in plasma and mammary tissue, and greater effect on prostaglandin E(2) levels than the corresponding diet dosing. This study illustrates potential pitfalls and limitations in trying to generalize based on data obtained with different oral dosing schemes and their extrapolation to potential efficacy and health risks in humans.

Phase II Evaluation of Docetaxel Plus Exisulind in Patients With Androgen Independent Prostate Carcinoma

OBJECTIVES

In this phase II study, the combination of docetaxel and exisulind (a GMP phosphodiesterase inhibitor) was given to patients with metastatic androgen independent prostate cancer (AIPC) to establish efficacy, assess toxicity, and determine pharmacokinetics of docetaxel administered alone and in combination with exisulind.

METHODS

Fourteen patients with metastatic AIPC were registered to receive weekly docetaxel for 4 weeks, followed by 2 weeks of rest; repeated up to a maximum of 6 cycles. Exisulind 250 mg was given orally twice a day starting on day 8 of the study and taken continuously.

RESULTS

All patients were evaluable for toxicity, response and survival. Grade 3 reversible toxicities included: fatigue, nausea, diarrhea, abdominal pain, rash, syncope, pulmonary edema, deep vein thrombosis, congestive heart failure, and elevations in transaminases, requiring therapy delays and/or dose reductions, or removal from therapy. Only 3 out of 14 patients (21.4%) had a 50% decline in prostate specific antigen (PSA) level that lasted > or =4 weeks; 1 out of 14 patients (7%) had a lymph node response. Median survival was 17.28 months. Docetaxel pharmacokinetics for 11 patients demonstrated mean +/- SD clearance values that were similar during week 1 and week 3 when exisulind had been added.

CONCLUSIONS

: Overall, our trial indicated that the toxicity profile and efficacy of this regimen is unlikely to be substantially better than single agent docetaxel.

Capillary electrophoresis combining field-amplified sample stacking and electroosmotic flow suppressant for analysis of sulindac and its two metabolites in plasma

Field-amplified sample stacking with electroosmotic flow (EOF) suppressant in capillary electrophoresis was used to determine the concentration of sulindac (SU) and its two active metabolites, sulindac sulfide (SI) and sulindac sulfone (SO), in human plasma. After acidification, the analytes were extracted from the plasma with dichloromethane. Before sample loading, a water plug (0.5 psi, 3 s) was injected to contain sample anions and to permit field-amplified stacking. Electrokinetic injection at a reversed voltage (-6 kV, 99.9 s) was then used to introduce anions. Separation was performed using phosphate buffer (80 mM, pH 6.0) containing 2,6-di-O-methyl-beta-cyclodextrin (0.75 mM), and poly(ethylene oxide) (0.01%) as an EOF suppressant. The separation was performed at -30 kV and 200 nm. During method validation, calibration plots were linear (r > 0.994) over a range of 0.3-30.0 microM for SU and SO, and 0.5-30.0 microM for SI. During intra- and inter-day analysis, relative standard deviations (RSD) and relative errors (RE) were all less than 16%. The limits of detection were 0.1 microM for SU and SO, and 0.3 microM for SI (S/N = 4, sampling 99.9s at -6 kV). This method was feasible for determining SU and its metabolites in plasma. One female volunteer (27 years, 42 kg) was orally administered one SU tablet (Clinoril, 20 0 mg/tab), and blood samples were drawn at regular intervals over an 8h period. After pretreatment and analysis, the plasma levels of SU, SI and SO were monitored. The pharmacokinetic profile of SU was also investigated.

A phase I clinical and pharmacokinetic study of the multi-drug resistance protein-1 (MRP-1) inhibitor sulindac, in combination with epirubicin in patients with advanced cancer

PURPOSE

Multi-drug resistance mediated by ATP-binding cassette trans-membrane protein pumps is an important cause of cancer treatment failure. Sulindac has been shown to be a competitive substrate for the clinically important resistance protein, multi-drug resistance protein-1 (MRP-1), and thus might enhance the anti-cancer activity of substrate chemotherapeutic agents, e.g. anthracyclines.

METHODS

We conducted a dose-escalating, single arm, prospective, open label, non-randomised phase I trial of epirubicin (75 mg/m(2)) in combination with escalating oral doses of sulindac (0-800 mg) in patients with advanced cancer to identify an appropriate dose of sulindac to use in future resistance studies. Anthracycline and sulindac pharmacokinetics were studied in cycles 1 and 3.

RESULTS

Seventeen patients (8 breast, 3 lung, 2 bowel, 1 melanoma, 1 renal, 1 ovarian and 1 of unknown primary origin, 16/17 having had prior chemotherapy) were enrolled. Eight patients received a full six cycles of treatment; 14 patients received three or more cycles. Dose-limiting toxicity was observed in two patients at 800 mg sulindac (1 renal impairment, 1 fatal haemoptysis in a patient with advanced lung cancer), and sulindac 600 mg was deemed to be the maximum tolerated dose. Sulindac had no effect on epirubicin pharmacokinetics. Among 15 patients with evaluable tumour, two partial responses were seen (malignant melanoma and breast cancer). Four others had prolonged stable disease.

CONCLUSION

Epirubicin 75 mg/m(2) and sulindac 600 mg are the recommended doses for phase II studies for these agents in combination.

A Phase I/II Study of Exisulind in Combination with Docetaxel/Carboplatin in Patients with Metastatic Non–Small-Cell Lung Cancer

Exisulind is a sulfone derivative of sulindac that induces apoptosis and demonstrates synergy with docetaxel in lung cancer models. This study evaluated the safety, efficacy, and pharmacokinetic interactions of exisulind and docetaxel/carboplatin in patients with metastatic non-small-cell lung cancer (NSCLC). Fifty-seven patients received 218 cycles of docetaxel (75 mg/m2) and carboplatin (area under the curve, 5.0) in combination with exisulind (125-250 mg orally twice daily). Two complete responses and 9 partial responses were observed among the 47 patients assessable for response (overall response rate, 23%). The median duration of response was 5.9 months and median survival was 9.4 months. The 1- and 2-year survival rates are 35% and 14%, respectively. The hematologic toxicities were consistent with those previously reported with docetaxel/carboplatin. The most common nonhematologic toxicities were mild to moderate fatigue, anorexia, nausea, and vomiting. The addition of exisulind to the chemotherapy regimen did not interfere with the metabolism or elimination of docetaxel and vice versa, and docetaxel did not interfere with the pharmacokinetic parameters of exisulind. This trial did not allow direct comparison of patients receiving docetaxel/carboplatin with and without exisulind, but when compared with historical data of docetaxel/carboplatin alone, the addition of exisulind does not appear to enhance antitumor activity, duration of response, or survival. Although preclinical data demonstrate increased apoptosis and prolonged survival for the combination of exisulind and docetaxel, multiple clinical trials do not support further clinical development of this combination regimen in patients with advanced NSCLC.

Exisulind: Aptosyn, FGN 1, Prevatac, sulindac sulfone

Exisulind [Aptosyn trade mark, FGN 1 trade mark, Prevatac trade mark, sulindac sulfone], the sulfone derivative of sulindac, is the lead compound in a series of selective apoptotic antineoplastic drugs (SAANDs) being developed by OSI Pharmaceuticals. The compounds were originally developed by Cell Pathways, which was acquired by, and integrated into, OSI Pharmaceuticals in June 2003. Exisulind inhibits the enzyme cyclic GMP phosphodiesterase (GMP-PDE), overexpressed in precancerous and cancerous colorectal cells, and induces apoptosis in such cells with minimal effects on normal cells. This apoptotic effect is independent of COX I or COX II inhibition, p53, Bcl-2, or cell-cycle arrest. Preclinical evidence suggests that exisulind also inhibits angiogenesis. Cell Pathways has formed sales and distribution agreements with three healthcare-related companies in the US for its future marketing and support campaign for exisulind. Innovex will hire and train sales representatives for Cell Pathways to launch and promote exisulind, Livingston Healthcare Services will be responsible for customer service, order and distribution administration, and Lash Group will be responsible for the development and implementation of reimbursement support services for exisulind. Cell Pathways has issued an exclusive licence for exisulind to Paladin Labs of Montreal, Canada. The agreement allows Paladin exclusive rights to commercialise the drug in Canada. In August 1999 Cell Pathways submitted an NDA application to the US FDA for exisulind (Aptosyn) for the treatment of familial adenomatous polyposis (FAP). However, in September 2000, the FDA announced that it had found deficiencies in the safety and efficacy data of Cell Pathways' NDA, and returned a non-approvable letter to the company. Cell Pathways then initiated another phase III study of the agent in combination with Aventis' docetaxel and comparing combination therapy with docetaxel alone. Exisulind has fast-track designation for FAP in the US. Phase I and II paediatric trials are also underway in the US. Cell Pathways announced in April 2000 that it had completed enrollment in an open-label phase II study in children with familial adenomatous polyposis (FAP). Patients will be evaluated to determine whether polyp numbers have been reduced after 1 year relative to baseline. In June 2000, Cell Pathways announced the results of a 1-year extension of a 1997-1999 phase III trial that showed that exisulind significantly reduced polyp formation in patients with FAP. Enrollment of 282 patients in a multicentre, placebo-controlled phase III trial for the treatment of sporadic colonic polyps was completed in the US in May 1999. In its 2003 Annual Report, Paladin Labs announced that it is conducting a phase III study of exisulind in patients with prostate cancer in Canada. Exisulind has completed a pivotal phase II/III trial for preventing the recurrence of prostate cancer in the US. Two phase II prostate cancer trials were initiated in June 1999. The first study assessed the efficacy of exisulind in 15 patients who had undergone prostatectomy, were receiving LHRH-agonist hormone therapy and had increasing PSA levels (study EX1001). The second trial was to enroll 20 hormone-refractory patients scheduled for radical prostatectomy within 2-8 weeks of diagnosis (study EX1004). This study compared the effect of exisulind + docetaxel on the rate of apoptosis and GMP-PDE expression in premalignant or malignant and normal prostate tissue. Cell Pathways and Rhône-Poulenc Rorer (now Aventis) agreed to collaborate on clinical trials of exisulind in combination with docetaxel in the treatment of various solid tumours. The first phase I/II trial (study 026) was to enroll previously untreated patients with non-small cell lung cancer (NSCLC). OSI Pharmaceuticals and Bristol-Myers Squibb are conducting a phase I/II trial (study EX 2002) of exisulind in combination with paclitaxel and carboplatin as first-line treatment for patients with NSCLC. Both companies will share costs and information gathered from the SCLC. Both companies will share costs and information gathered from the trial. A phase I/II trial (study EX 2006) of weekly paclitaxel and carboplatin combined with exisulind is also underway in patients with advanced NSCLC. Cell Pathways and Glaxo Wellcome are cooperating in supporting a clinical trial (study EX 2004) of exisulind in combination with vinorelbine as first-line treatment for elderly patients with advanced NSCLC. The study will be conducted at the University of Wisconsin, and the two companies will share the costs of the trial while maintaining the rights to their respective compounds. Cell Pathways and Eli Lilly have a phase I/II trial (study EX 2005) of exisulind in combination with gemcitabine underway in patients with NSCLC. This study will investigate the efficacy and tolerability of escalating doses of exisulind in combination with a standard gemcitabine regimen. The Cancer and Leukaemia Group B (CALGB) initiated a phase II study of exisulind in combination with etoposide and carboplatin in patients with small cell lung cancer in the US in September 2002. The Eastern Cooperative Oncology Group (ECOG) initiated a phase II study in NSCLC patients in September 2002 that will investigate the effects of exisulind in combination with gemcitabine and carboplatin. The objectives of the two studies are to determine the 12-month survival rate and response rates following treatment with the combination regimens. Patents covering the mechanism of action of exisulind have been allowed in Europe and Japan, and extend to the methods of identifying compounds that selectively stimulate apoptosis in precancerous and cancerous cells.

A Phase I and Pharmacokinetic Study of Exisulind and Docetaxel in Patients with Advanced Solid Tumors

PURPOSE

Exisulind (sulindac sulfone, FGN-1, Aptosyn) is a sulindac metabolite that induces apoptosis via inhibition of cyclic GMP-phosphodiesterase. This agent demonstrated tumor growth inhibition in rodent models of colon, breast, prostate, and lung carcinogenesis. In an orthotopic model of human non-small-cell lung cancer, the combination of exisulind and docetaxel prolonged survival in athymic nude rats, forming the basis of this phase I combination study.

EXPERIMENTAL DESIGN

This study evaluated the toxicity and pharmacokinetics of combining exisulind (150-250 mg) given orally twice daily and docetaxel (30-36 mg/m2) administered intravenously on days 1, 8, and 15 of a 4-week cycle.

RESULTS

Twenty patients with a range of advanced solid tumors (median age, 59 years; age range, 35-77 years; median performance status, 1) received a total of 70 courses. Observed adverse events were mild to moderate, and there was no dose-limiting toxicity at any level. Grade 3 gastrointestinal toxicities were present in 10 of the 70 cycles (10%) and included nausea, vomiting, dyspepsia, and elevated alkaline phosphatase. Neutropenia was present in four cycles in patients treated with a docetaxel dose of 36 mg/m2. Pharmacokinetic analysis did not demonstrate a clear effect of exisulind on docetaxel pharmacokinetics and vice versa. Relationships were evident between the plasma concentration of exisulind and the development of grade 2 or greater toxicities. One third of patients maintained stable disease for 3 to 12 cycles, but no objective responses were observed.

CONCLUSIONS

The combination of docetaxel (36 mg/m2, weekly) and exisulind (500 mg/d) was reasonably well tolerated, and it is undergoing phase II testing in patients with non-small-cell lung cancer.

Phase I and pharmacokinetic trial of the proapoptotic sulindac analog CP-461 in patients with advanced cancer

CP-461 is a member of a class of novel proapoptotic drugs that specifically inhibit cyclic GMP phosphodiesterases but not cyclooxygenase-1 or -2. CP-461 inhibits the growth of a broad range of human tumor cell lines in vitro at micromolar concentrations and selectively induces apoptosis in cancer cell lines but not normal cells. Preclinical studies revealed good oral bioavailability and no toxicity in dogs and rats at single doses up to 500 mg/kg. In a Phase I trial, 21 patients with a range of solid tumors and good performance status received CP-461 p.o. twice daily for 28 consecutive days. Cycles were repeated without a treatment-free interval. CP-461 doses ranged from 100 to 800 mg/day. Therapy was well tolerated overall, and a maximum tolerated dose was not reached. Grade 3 asymptomatic aspartate aminotransferase/alanine aminotransferase elevation in 1 patient treated at 800 mg/day was the only dose-limiting toxicity. No hematologic toxicity was noted. Peak plasma concentrations occurred between 1 and 2 h after dosing, and doses above 200 mg/day exceeded the known in vitro EC(50) (1-2 micro M) for apoptosis in cancer cells. No drug was detectable after 24 h of administration, and the terminal half-life was 6.7 h. The area under the plasma concentration-time curve was dose-proportional from 200 to 800 mg/day. Four patients exhibited disease stability after two cycles of treatment. CP-461 is minimally toxic at doses up to 800 mg/day when administered p.o. on a twice-daily schedule.

Preclinical and clinical studies of docetaxel and exisulind in the treatment of human lung cancer

Lung cancer is the leading cause of cancer death in the United States. The majority of patients with non-small cell lung cancers present with inoperable disease because of the presence of metastases to regional lymph nodes or other metastatic sites. About one third of patients have stage IV disease with metastases to distant organs at the time of diagnosis. The prognosis for these patients is very poor. With best supportive care the median survival is only 4 months and the 1-year survival rate is 10% to 15%. Current chemotherapy combinations improve the survival and quality of life for patients with advanced non-small cell lung cancer. With two-drug combinations, median survival is increased to 8 months or more and 1-year survival is increased to 35% to 40%. Still, complete response rates are low and more than 80% of patients die within 1 year of diagnosis. The improvements created by current therapies led to studies of chemotherapy in the second-line setting. Docetaxel has been shown to improve survival of patients who failed platinum-based chemotherapy and was approved by the U.S. Food and Drug Administration for therapy in this setting. However, response rates were very low and survival very short. Therefore, new therapies are urgently needed. Exisulind is a novel oral anticancer agent that holds promise for the treatment of patients with advanced non-small cell lung cancer. Exisulind was originally developed as a chemoprevention agent for colorectal cancer. Preclinical studies showed that exisulind could prevent polyp formation and inhibit the growth of colorectal cancers. Subsequent preclinical studies showed that exisulind also inhibited the growth of human breast, prostate, and lung cancers. Phase I clinical studies showed that twice-daily oral doses could be given safely and would provide peak concentrations that were equivalent to those required for in vitro effects. These observations lead to the studies of the combination of exisulind and docetaxel in preclinical and clinical studies in human lung cancer described in this article.

Exisulind, a selective apoptotic antineoplastic drug

Exisulind (Aptosyn, Cell Pathways, Inc.) is the first of a new class of targeted, pro-apoptotic drugs that show promise in the treatment of cancer. These agents induce apoptosis (i.e., programmed cell death) in a broad range of pre-cancerous and cancerous tissues without affecting normal cells. The antineoplastic effect of exisulind appears to be the result of activation of protein kinase G (PKG) which leads to multiple downstream effects culminating in apoptosis. Exisulind has demonstrated antineoplastic activity in solid tumour and haematological cancer cell lines and is an inhibitor of tumour growth in rodent models of colon, prostate, bladder, mammary and lung cancer. Preclinical data evaluating selective apoptotic antineoplastic drugs (SAANDs) in combination with various chemotherapy drugs indicates additive or synergistic antineoplastic effects. In clinical studies, exisulind prevented colorectal polyp formation in patients with familial adenomatous polyposis (FAP) over 24 months. In a randomised, placebo-controlled study of prostate cancer patients, exisulind inhibited the rise of prostate-specific antigen (PSA) in men with PSA progression after radical prostatectomy. Exisulind has been well-tolerated by most patients in clinical trials. In conclusion, preclinical evidence and early clinical results suggest that exisulind and other drugs in this class may have wide applications in treating cancer both as monotherapy and in combination with chemotherapy and other targeted agents.

Chemoprevention of intestinal polyposis in the Apcdelta716 mouse by rofecoxib, a specific cyclooxygenase-2 inhibitor

Mutations in the human adenomatous polyposis (APC) gene are causative for familial adenomatous polyposis (FAP), a rare condition in which numerous colonic polyps arise during puberty and, if left untreated, lead to colon cancer. The APC gene is a tumor suppressor that has been termed the "gatekeeper gene" for colon cancer. In addition to the 100% mutation rate in FAP patients, the APC gene is mutated in >80% of sporadic colon and intestinal cancers. The Apc gene in mice has been mutated either by chemical carcinogenesis, resulting in the Min mouse Apcdelta850, or by heterologous recombination, resulting in the Apcdelta716 or Apedelta1368 mice (M. Oshima et al., Proc. Natl. Acad. Sci. USA, 92: 4482-4486, 1995). Although homozygote Apc-/- mice are embryonically lethal, the heterozygotes are viable but develop numerous intestinal polyps with loss of Apc heterozygosity within the polyps (M. Oshima et al., Proc. Natl. Acad. Sci. USA, 92: 4482-4486, 1995). The proinflammatory, prooncogenic protein cyclooxygenase (COX)-2 has been shown to be markedly induced in the Apcdelta716 polyps at an early stage of polyp development (M. Oshima et al., Cell, 87: 803-809, 1996). We demonstrate here that treatment with the specific COX-2 inhibitor rofecoxib results in a dose-dependent reduction in the number and size of intestinal and colonic polyps in the Apcdelta716 mouse. The plasma concentration of rofecoxib that resulted in a 55% inhibition of polyp number and an 80% inhibition of polyps > 1 mm in size is comparable with the human clinical steady-state concentration of 25 mg rofecoxib (Vioxx) taken once daily (A. Porras et al., Clin. Pharm. Ther., 67: 137, 2000). Polyps from both untreated and rofecoxib- or sulindac-treated Apcdelta716 mice expressed COX-1 and -2, whereas normal epithelium from all mice expressed COX-1 but minimal amounts of COX-2. Polyps from either rofecoxib- or sulindac-treated mice had lower rates of DNA replication, expressed less proangiogenic vascular endothelial-derived growth factor and more membrane-bound beta-catenin, but showed unchanged nuclear localization of this transcription factor. This study showing the inhibition of polyposis in the Apcdelta716 mouse suggests that the specific COX-2 inhibitor rofecoxib (Vioxx) has potential as a chemopreventive agent in human intestinal and colon cancer.

Phase I trial of exisulind (sulindac sulfone, FGN-1) as a chemopreventive agent in patients with familial adenomatous polyposis

Exisulind (sulindac sulfone; FGN-1), a metabolite of sulindac without known effects on prostaglandin synthesis, can promote apoptosis and inhibit tumorigenesis in preclinical systems. We performed a Phase I trial of this compound in patients with familial adenomatous polyposis (FAP) to examine the tolerability and safety of this drug in the cancer chemoprevention setting. Six patients each were treated with exisulind at doses of 200, 300, and 400 mg p.o. twice a day. Reversible hepatic dysfunction was noted in four of six patients treated at the 400-mg p.o., twice-a-day dose level, but in only one to two of six patients treated at each of the lower dose levels. The serum half-life of exisulind was 6-9 h; little drug accumulation was noted over time. A nonsignificant trend toward increased apoptosis in polyps was noted at the maximum tolerated dose, but no decrease in polyp numbers or significant effects on cellular proliferation was noted. After treatment, polyps tended to display a "halo" appearance grossly and mucinous differentiation histologically. The maximum safe dose of exisulind is 300 mg p.o. twice a day in patients with subtotal colectomies. Reversible hepatic dysfunction limits further dose escalation. A decrease in polyp numbers could not be demonstrated, but the trend toward increased apoptosis at the MTD and the observation of mucinous change histologically suggest that further investigation of drugs of this class might be warranted.

Sulindac is excreted into bile by a canalicular bile salt pump and undergoes a cholehepatic circulation in rats

BACKGROUND & AIMS

Dihydroxy bile acids induce a bicarbonate-rich hypercholeresis when secreted into canalicular bile in unconjugated form; the mechanism is cholehepatic shunting. The aim of this study was to identify a xenobiotic that induces hypercholeresis by a similar mechanism.

METHODS

Five organic acids (sulindac, ibuprofen, ketoprofen, diclofenac, and norfloxacin) were infused into rats with biliary fistulas. Biliary recovery, bile flow, and biliary bicarbonate were analyzed. Sulindac transport was further characterized using Tr(-) rats (deficient in mrp2, a canalicular transporter for organic anions), the isolated perfused rat liver, and hepatocyte membrane fractions.

RESULTS

In biliary fistula rats, sulindac was recovered in bile in unconjugated form and induced hypercholeresis of canalicular origin. Other compounds underwent glucuronidation and were not hypercholeretic. In the isolated liver, sulindac had delayed biliary recovery and induced prolonged choleresis, consistent with a cholehepatic circulation. Sulindac was secreted normally in Tr(-) rats, indicating that its canalicular transport did not require mrp2. In the perfused liver, sulindac inhibited cholyltaurine uptake, and when coinfused with cholyltaurine, induced acute cholestasis. With both basolateral and canalicular membrane fractions, sulindac inhibited cholyltaurine transport competitively.

CONCLUSIONS

Sulindac is secreted into bile in unconjugated form by a canalicular bile acid transporter and is absorbed by cholangiocytes, inducing hypercholeresis. At high flux rates, sulindac competitively inhibits canalicular bile salt transport; such inhibition may contribute to the propensity of sulindac to induce cholestasis in patients.

Chemopreventive efficacy of sulindac sulfone against colon cancer depends on time of administration during carcinogenic process

Epidemiological and model studies with laboratory animals have provided evidence that nonsteroidal anti-inflammatory drugs reduce the risk of colon cancer. Sulindac, a nonsteroidal anti-inflammatory drug, has been shown to inhibit azoxymethane (AOM)-induced colon carcinogenesis in rats when administered continuously before, during, and after carcinogen treatment (initiation and postinitiation periods) or when given continuously beginning 14 weeks after carcinogen administration (promotion/ progression stage). The present study was designed to investigate the chemopreventive efficacy of sulindac sulfone (exisulind), the sulfone metabolite of sulindac, when administered during the promotion/progression stage of colon carcinogenesis in comparison to the effect during the initiation and postinitiation periods. We have also studied the modulating effect of exisulind on colonic tumor apoptosis. At 5 weeks of age, groups of male F344 rats were fed diets containing 0%, 0.06%, and 0.12% exisulind. At 7 weeks of age, groups of animals were injected s.c. with AOM (15 mg/kg body weight, once weekly for 2 weeks). Animals intended for the promotion/progression study and receiving 0% exisulind were switched to an experimental diet containing 0.12% exisulind at 14 weeks after the second AOM treatment. All rats remained on their respective dietary regimens until the termination of the study, 50 weeks after the second AOM injection. Colon tumors were evaluated histopathologically for tumor type. Administration of 0.06% and 0.12% exisulind during the initiation and postinitiation periods significantly inhibited the incidence and multiplicity of invasive and/or noninvasive adenocarcinomas of the colon. The inhibition of colon tumorigenesis by exisulind was associated with a significant retardation of body weight gain shortly after sulfone administration and increased apoptosis in the colon tumors. In contrast, administration of the higher dose (0.12%) of exisulind during the promotion/progression stage had only minimal effects on colon tumorigenesis and apoptosis in the colon tumors, suggesting that early administration, but not late administration, may be required for chemopreventive efficacy of this drug.

Placental transfer of sulindac, sulindac sulfide, and indomethacin in a human placental perfusion model

OBJECTIVE

Evaluation of the transplacental transfer and placental metabolism of sulindac, its active sulfide metabolite, and indomethacin, drugs used as tocolytic agents, in dual recirculating human placental perfusion.

STUDY DESIGN

Term placentas were obtained with maternal consent immediately after delivery. Drugs were added to the maternal reservoir, together with antipyrine as a reference compound, and disappearance from the maternal circulation and appearance in the fetal circulation were followed up for 2 hours in 4 experiments for each compound. Drug concentrations were analyzed by high-performance liquid chromatography.

RESULTS

The fetal/maternal concentration ratios after 2-hour perfusions were 0. 34 +/- 0.19 (mean +/- SD, sulindac), 0.54 +/- 0.17 (sulfide), and 0. 45 +/- 0.16 (indomethacin), and the fetal-maternal transfer percentages at 2 hours were 11.6 +/- 5.9 (sulindac), 18.2 +/- 5.2 (sulfide), and 15.3 +/- 4.5 (indomethacin). No metabolism of sulindac or indomethacin was detected.

CONCLUSION

Sulindac sulfide, formed through hepatic metabolism, reaches the fetus in higher concentrations than does sulindac or indomethacin. Neither sulindac nor indomethacin is metabolized by the human placenta.

Sulindac sulfone inhibits azoxymethane-induced colon carcinogenesis in rats without reducing prostaglandin levels

Nonsteroidal anti-inflammatory drugs (NSAIDs), such as sulindac, have cancer chemopreventive properties by a mechanism that has been suggested to involve cyclooxygenase inhibition and reduction of prostaglandin (PGE2) levels in the target tissue. To test this hypothesis, we studied the effect of dietary sulindac sulfone (500-2000 ppm), a metabolite of sulindac reported to lack cyclooxygenase inhibitory activity, on tumor formation and PGE2 levels in the azoxymethane model of colon carcinogenesis. Rats treated with sulindac at 400 ppm and piroxicam at 150 ppm were used as positive controls. Rats received two s.c. injections of azoxymethane (15 mg/kg) for 2 weeks and were fed either experimental or control diets until necropsy. After 31 weeks of sulfone treatment, a dose-related increase in sulfone levels in both serum and cecal contents was measured; there was no evidence of metabolic conversion to sulindac or other metabolites. Rats treated with sulfone at 1000 and 2000 ppm, sulindac, and piroxicam had significantly fewer colonic adenomas and carcinomas compared with rats fed control diet as measured by tumor incidence, multiplicity, and tumor burden. Sulfone-treated rats also showed a dose-response relationship for inhibiting all tumor parameters. Colons from rats treated with sulindac or piroxicam contained PGE2 levels that ranged from approximately 16-49% of control levels. PGE2 levels in rats treated with sulfone up to 2000 ppm ranged from 78-118% of control levels. Moreover, the effects of sulindac sulfone on various enzymes responsible for regulating prostaglandin levels were evaluated. No significant inhibitory effects were observed for cyclooxygenase, lipoxygenase, or phospholipase A2. These results suggest that reduction of prostaglandin levels in the target tissue may not be necessary for the chemopreventive properties of sulindac.

Clinical pharmacokinetics of sulindac. A dynamic old drug

Sulindac is a nonsteroidal anti-inflammatory drug (NSAID) of the indene acetic acid class. The absorption of sulindac is rapid when given orally. Sulindac is reversibly metabolised to sulindac sulphide which has anti-inflammatory and analgesic properties and is irreversibly metabolised to sulindac sulphone which has been suggested to possess antiproliferative effects against tumours. Sulindac and its sulphide and sulphone metabolites bind extensively to plasma albumin. Sulindac is eliminated following bio-transformation; sulindac and sulindac sulphone and their respective glucurooconjugated metabolites are excreted in urine; however only a small amount of the sulindac sulphide metabolite is eliminated in urine. Following long term twice daily administration both sulindac and its metabolites accumulate in plasma. Both patients with cirrhosis and the elderly demonstrate elevated concentrations of all species upon long term sulindac administration as compared with a single dose. The disposition of sulindac and its metabolites may be tied to renal function. In end-stage renal disease, increased free fractions of all species and accumulation of the sulphide and sulphone metabolites, and to a lesser extent sulindac, occurs. Significant drug interactions have been demonstrated for dimethylsulphoxide, cyclosporin, furosemide (frusemide), hydrochlorothiazide, methotrexate and cholestyramine.

Absorption of sulindac from a novel (Pro-SorbTM) liquid formulation

The absorption of sulindac from two different 200 mg oral dosage forms, Pro-SorbTM liquid and Clinoril tablets, was compared following administration to eight healthy human volunteers. Subjects received both formulations according to a randomized crossover design and blood samples were collected at selected times during 24 h. Concentrations of both sulindac and its active sulphide metabolite were determined by HPLC and individual serum concentration versus time profiles were constructed. Maximal serum concentrations (Cmax) and area under the curve values (AUClast and AUC0-infinity) were compared for both sulindac and sulindac sulphide. The results indicate that the rate and extent of absorption of sulindac from Pro-SorbTM liquid are significantly greater than those from Clinoril tablets, a finding consistent with the observation that the liquid form produces less gastric irritation following oral administration.

Human placental transfer of the prostaglandin inhibitor sulindac using an in vitro model

OBJECTIVE

We determined whether the prostaglandin inhibitor sulindac crosses the human placenta.

METHODS

The recirculating single-cotyledon placenta model was used to characterize the maternal-to-fetal and fetal-to-maternal transport of 14C-labeled sulindac in normal term placentas perfused immediately after delivery. Antipyrine was added as a standard for simple diffusion. Serial samples were taken from both reservoirs during each 3-hour perfusion. Transport was calculated using liquid scintillation spectrometry for 14C-labeled sulindac and high-performance liquid chromatography for antipyrine.

RESULTS

There was significant maternal-to-fetal transfer of sulindac. The mean (+/- SD) transfer at 2 hours was 7.22 +/- 2.57%. The fetal-to-maternal transfer was similar at 10.75 +/- 3.80%. The mean maternal/fetal concentration ratio of sulindac was 0.42 at 3 hours. Placental uptake ranged from 24-45 ng/g of placenta.

CONCLUSIONS

Sulindac crosses the human placenta in small but significant amounts. The transport is similar in both directions, implying simple diffusion.

Influence of cholestyramine resin administration on single dose sulindac pharmacokinetics

Cholestyramine, a nonabsorbable anion exchange resin, has been reported to bind concomitantly administered drugs and decrease their bioavailability. The objective of the study was to determine cholestyramine effect on the plasma concentrations of sulindac and its sulfide metabolite following concurrent and staggered (sulindac 3 hours before cholestyramine) dosing. Six healthy volunteers participated in an open-label, 3-way crossover study. Subjects received 400 mg sulindac orally followed by serial blood sampling for sulindac and sulindac sulfide plasma concentrations over a 24-hour period. During the concurrent phase, 4 g of cholestyramine was coadministered resulting in a decrease (p < 0.05) in the area under the curve (AUC) for sulindac compared to sulindac alone (7.11 +/- 3.25 micrograms-h/ml vs 31.65 +/- 7.94 micrograms-h/ml respectively). Also, the sulindac sulfide AUC decreased (p < 0.05) to 7.26 +/- 4.37 micrograms-h/ml coadministration of both drugs compared to 44.69 +/- 11.81 micrograms-h/ml when sulindac is given alone. When the same doses of each drug were given 3 hours apart, the AUC for sulindac (17.88 +/- 3.69 micrograms-h/ml) and its sulfide metabolite (20.12 +/- 7.46 micrograms-h/ml) were still significantly decreased (p < 0.05) when compared to sulindac given alone (31.65 +/- 7.94 micrograms-h/ml for sulindac and 44.69 +/- 11.81 micrograms-h/ml for sulindac sulfide). Based on the lower AUCs for sulindac and sulindac sulfide, separating sulindac and cholestyramine by 3-hour intervals did not prevent the interaction. It is likely that the enterohepatic recycling features of sulindac may not prevent the interaction with cholestyramine even when the 2 drugs are staggered.

Pharmacokinetics and dialyzability of sulindac and metabolites in patients with end-stage renal failure

Sulindac was administered as a single 300-mg oral dose to six patients with end-stage renal failure and six normal subjects. Plasma concentrations of sulindac and its sulfide and sulfone metabolites were examined over a 48-hour period. As determined by ultrafiltration methods at 37 degrees C, the percentage free of sulindac and sulindac sulfide in plasma was greater, respectively, in the patients with renal failure (10.50 +/- 2.42 and 9.96 +/- 1.21) than in the normal subjects (6.78 +/- 0.45 and 6.01 +/- 0.37). Free sulindac plasma concentrations were not different between the two groups. However, sulindac sulfide, total and free, plasma concentrations were substantially decreased in the group with renal failure. Total area under the curve (AUC) of the sulfide metabolite was 18% in the normal subjects and the free AUC was 29%. In patients with renal failure, the apparent half-lives of sulindac (1.98 +/- 0.76 hours) and sulindac sulfide (15.6 +/- 5.8 hours) were not different from those of normal subjects. Sulindac sulfone half-life was highly variable and longer in the patient group. Studies of dialysis clearance showed that sulindac and its metabolites are poorly dialyzed. A 4-hour dialysis period increased the plasma binding of both sulindac and sulindac sulfide in the patient group. Based on the decreased plasma concentration of the active sulindac sulfide metabolite in the patient group, dosage adjustments may be required in patients with end-stage renal failure.

Inhibitory effects of nonsteroidal anti-inflammatory drugs (NSAIDs) on the metabolism of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) in mouse lung explants

Our previous study showed that the nonsteroidal anti-inflammatory drug (NSAID), sulindac, inhibited lung tumorigenesis induced by the tobacco-specific carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK). In this paper, we describe the metabolism of sulindac and its sulfide metabolite and their inhibition of NNK metabolism in lung tissues cultured in vitro. The extent of oxidation of sulindac to the sulfone metabolite was linear with time (0 to 16 hr) and with concentration (0 to 1 mM). The sulfide metabolite was oxidized to sulindac more rapidly than sulindac was oxidized to the sulfone metabolite. The three metabolic pathways of 2.36 microM NNK in lung tissues are alpha-carbon hydroxylation, pyridine N-oxidation, and carbonyl reduction. alpha-Carbon hydroxylation and pyridine N-oxidation were not significantly inhibited by 100 microM sulindac. In contrast, 100 microM sulfide metabolite inhibited overall alpha-carbon hydroxylation by 35% (p < 0.001) and pyridine N-oxidation by 32% (p < 0.001). The sulfide had no effect on carbonyl reduction. We conclude that the sulfide is competing with NNK for the same monooxygenase enzyme system. We have compared the extent of inhibition of 2.36 microM NNK metabolism by 5 NSAIDs. Sulindac was the least effective and naproxen and ibuprofen were the most effective. Naproxen and ibuprofen inhibited the alpha-carbon hydroxylation of NNK by 72%. Inhibition of this pathway by indomethacin and piroxicam was 32% and 28%, respectively. Inhibition by sulindac (20%) was not statistically significant. These results indicate that NSAIDs inhibit carcinogen activation in target tissues.(ABSTRACT TRUNCATED AT 250 WORDS)

NSAIDs: maternal and fetal considerations

Nonsteroidal anti-inflammatory drugs (NSAIDs) gained popularity in the late 1970s. Inhibition of prostaglandin synthesis with indomethacin has been reported to be effective for prevention of labor and for treatment for symptomatic polyhydramnios. Concern about its possible constrictive effect on the fetal ductus arteriosus has limited its use in pregnancy. Maternal indomethacin therapy has also been associated with reduction in urine production in the fetus and with oligohydramnios. Obstetricians have discouraged pregnant women from taking analgesic doses of aspirin, mainly because of the availability of paracetamol (acetaminophen), which causes less gastric irritation, but also because of fear of maternal and fetal hemorrhage and of possible premature closure of the ductus. These fears largely derive from studies on patients taking large doses and from extrapolation from other NSAIDs. The likelihood that treatment with 60-75 mg/day of aspirin markedly reduces the incidence of preeclampsia and fetal intrauterine growth retardation makes it important to reexamine its use. This review describes the pharmacology and pharmacokinetics of aspirin with particular reference to pregnancy and considers teratogenesis, prolongation of pregnancy and labor, maternal bleeding, fetal and neonatal bleeding, possible effects on the ductus arteriosus and pulmonary circulation, and possible nonspecific effects on intelligence and breast feeding and acute toxicity in the neonate.

The role of metabolites in bioequivalency assessment. I. Linear pharmacokinetics without first-pass effect

The estimation of bioequivalency using metabolite data was investigated for immediate release formulations with drugs exhibiting linear pharmacokinetics and no first-pass effect. This was accomplished by generating parent drug and metabolite plasma level profiles assuming formation and excretion rate-limited pharmacokinetic models with absorption rate constants obtained from bivariate normal distributions and designated random errors. Simulation results indicated that bioequivalence determination using Cmax of parent drug and metabolite was independent of the metabolite models as evaluated by confidence interval approach. However, a clear difference with respect to the outcome of bioequivalence evaluation arises depending upon the utilization of Cmax values for the parent drug and metabolite. The major reason for this disparity was attributed to the minimal effect of the absorption process for the parent drug on the formation of the metabolite. This phenomenon results in an apparent lower intrasubject variability for Cmax of the metabolite and, in turn, a tighter confidence interval for Cmax of the metabolite in comparison with the parent drug. The simulated results have been found to be in agreement with the bioequivalency data for acetohexamide, allopurinol, procainamide, and sulindac. In all cases, the interval of the 90% confidence limit for Cmax of the metabolite is always smaller than that of the parent drug, regardless of the drug pharmacokinetics and the level of error contained in the data.

Sulindac kinetics and effects on renal function and prostaglandin excretion in renal insufficiency

The purpose of this study was to evaluate the pharmacokinetics of sulindac, a purported "renal sparing" nonsteroidal anti-inflammatory drug, and its effects on renal function and prostaglandin excretion in patients with reduced glomerular filtration rate. Twelve female patients (glomerular filtration rate 37 +/- 4 mL/min) were treated with sulindac 200 mg bid for 11 days. Urinary PGE2, 6-keto-PGF1 alpha and serum thromboxane (TxB2) generation were measured by radioimmunoassay (RIA) following extraction on C-18 columns. Glomerular filtration rate and effective renal plasma flow were measured by 99TC-DPTA and 131I-para-aminohippuric acid clearance. In six patients serum and urine levels of sulindac and its metabolites were measured by high-pressure liquid chromatography (HPLC). Sulindac was rapidly absorbed and converted to sulindac sulfide with peak levels 2 hours after a single dose, but steady state levels were not reached prior to drug discontinuation. Sulindac sulfide AUC (0-5 hours micrograms min/mL) progressively increased from 382 to 3,030 on day 11. It did not appear in the urine. Baseline urinary PGE2 and 6-keto-PGF1 alpha excretion were 23.8 +/- 5.6 and 18.9 +/- 2.7 ng/hr respectively and were reduced by 68% and 47% by day 4 of therapy. TxB2 generation fell by 34% after one dose and by 67% by day 11. There was a significant increase in serum creatinine from 1.88 +/- 0.13 mg/dl before treatment to 2.16 +/- 0.15 mg/dL (P less than .05) after eleven days.(ABSTRACT TRUNCATED AT 250 WORDS)

[Pharmacokinetics of sulindac in aged patients presenting with inflammatory joint disease]

The kinetic of sulindac and its two metabolites (sulfide and sulfone) was investigated in twelve elderly patients, following multiple oral dose administration of 400 mg/d. Data were compared to those obtained previously in ten healthy volunteers who received the same dosage regimen. Following multiple dose administration, accumulation ratios indicate that sulindac do not accumulate either in elderly patients (R = 1.35; R = AUC0-24 J8/AUC0-24 J1) or in healthy young subjects (R = 1.38; R = U0-24 J1). No significant modification of sulindac and sulfide kinetic parameters was observed. The apparent bioavailability of the inactive metabolite, sulfone, was found to be doubled in elderly patients (p less than 0.05). We conclude that there is no need to modify the dosage regimen of Arthrocine (400 mg once a day) in elderly patients.

[Prodrugs]

Prodrugs are pharmacologically inert and nontoxic chemical compounds which are transformed in vivo into pharmacologically and therapeutically active compounds, i.e. drugs. Prodrugs are used to solve problems which cannot be solved by the drugs themselves. There are three types of problems: problems arising before the drug enters the body (solubilization, stabilization and improved acceptability); problems associated with the penetration and fate of the drug in the body (absorption, barrier crossing, duration of action); problems relating to the therapeutic target (selective local delivery). The principal prodrugs that solve these problems and the mechanisms of the solutions they provide are described and discussed.

Deactivation of sulindac-sulphide by human renal microsomes

The renal metabolism of sulindac-sulphide was studied in subcellular fractions from human kidney. It was shown that renal microsomes, in the presence of NADPH, effectively catalyzed the sulphoxidation of sulindac-sulphide. Also the mitochondrial fraction catalyzed the reaction but at a ten-fold lower rate than the microsomes. Carbon monoxide, metyrapone and n-octylamine did not inhibit renal sulphoxidation of sulindac-sulphide and the reaction could occur in a monooxygenase containing fraction free from NADPH-cytochrome P-450 reductase. Hydroxylation of lauric acid was studied in microsomes and in the purified monooxygenase containing fraction under the same experimental condition as sulindac-sulphide sulphoxidation. Lauric acid is a substrate known to be metabolized by a renal cytochrome P-450 to 11 and 12-hydroxylated products. This reaction was sensitive to carbon monoxide and did not occur in the absence of NADPH cytochrome P-450 reductase. Based on these results we conclude that cytochrome P-450 plays at the most a limited role in human kidney metabolism of sulindac-sulphide. In contrast, sulphoxidation of sulindac-sulphide was substantially reduced in the presence of methimazole suggesting a role of the flavin-containing monooxygenase in the renal biotransformation of sulindac-sulphide in man.