Double-blind, placebo-controlled trial of famotidine in children with abdominal pain and dyspepsia: global and quantitative assessment.

To determine the benefit of using an H2-receptor antagonist in children with abdominal pain and dyspepsia, 25 such children were enrolled in a double-blind, placebo-controlled trial of famotidine. Global and quantitative pain assessments were done before and after each treatment period. The quantitative assessment was calculated based on the abdominal pain score that was the sum of three components. Based on the global evaluation, there was a clear benefit of famotidine over placebo (68% vs 12%). Using the quantitative assessment, however, the mean improvement of the score using famotidine versus placebo was not statistically significant (3.37+/-3.53 vs 1.66+/-2.7). There was a significant improvement in this score during the first treatment period regardless of medication used (period effect: P = 0.05). A subset of patients with peptic symptoms demonstrated a significant drug effect that outweighed the period effect (drug effect: P = 0.01; period effect: P = 0.02). We conclude that famotidine subjectively improves the symptoms of children with recurrent abdominal pain but not objectively using the derived score. However, famotidine is significantly more effective than placebo among children with peptic symptoms. The use of this simple scoring scale may facilitate selecting those children who will benefit from H2-receptor antagonist therapy.

Celecoxib, a selective cyclooxygenase-2 inhibitor for the treatment of rheumatoid arthritis and osteoarthritis.

Nonsteroidal anti-inflammatory drugs (NSAIDs) are among the most frequently prescribed drugs, despite their well-established association with gastroduodenal injury. Recent discovery of the cyclooxygenase (COX) isoenzymes COX-1 and COX-2 has improved our knowledge of the action of NSAIDs. COX-1 is continuously expressed in almost all tissues, where it converts arachidonate to the prostaglandins (PGs) important in homeostatic function; COX-2 is present in immune cells, blood vessel endothelial cells, and synovial fibroblasts. Classic NSAIDs inhibit both COX isoenzymes by occupying the cyclooxygenase-active site, preventing access by arachidonic acid. In theory, a drug such as celecoxib that selectively inhibited COX-2 might block inflammation, pain, and fever while reducing the side effects (gastric erosions and ulcers) associated with inhibition of COX-1. In animal models of inflammation and pain, celecoxib has shown marked suppression of PG production and inflammation compared with indomethacin, the standard COX-1/COX-2 inhibitor. In clinical trials, celecoxib dosed at 100, 200, and 400 mg BID was found to significantly reduce the signs and symptoms of rheumatoid arthritis (RA) and osteoarthritis. In one RA study, celecoxib was found to be as clinically effective as diclofenac after 24 weeks of treatment; at the end of the study, gastroduodenal ulcers occurred significantly more frequently in the diclofenac group (15%) than in the celecoxib group (4%). In a 1-week endoscopy study comparing celecoxib with naproxen and placebo, the incidence of gastric erosions/ulcers was significantly greater in the naproxen group than in the celecoxib or placebo group. The most common adverse effects of celecoxib in clinical studies were headache, diarrhea, abdominal discomfort, and dizziness. Celecoxib has shown significant equivalent anti-inflammatory and analgesic efficacy and has produced less endoscopically apparent gastrointestinal (GI) ulceration or erosion than have 3 classic NSAIDs. Whether it will have long-term GI adverse effects or interact with other medications to cause serious adverse responses (eg, increased GI bleeding or rash in conjunction with other sulfonamide-like drugs) is unknown and remains to be established.

An extended-release formulation of oxybutynin chloride for the treatment of overactive urinary bladder.

Detrusor instability, or urinary incontinence, is common in elderly patients, particularly elderly women. The clinical symptoms of overactive, or unstable, urinary bladder include urge urinary incontinence, urgency, and frequency. Mixed urinary incontinence, which comprises urge urinary incontinence and stress incontinence, is manifested by increased intraabdominal pressure on coughing or sneezing. The detrusor muscle of the bladder is under the control of the parasympathetic, or muscarinic, nervous system. The drug of choice in this condition is oxybutynin chloride, which has the ability to block acetylcholine released from parasympathetic nerves in the urinary bladder, preventing contractions of the muscle and exerting a direct spasmolytic effect on the bladder. A new extended-release oral tablet formulation, OROS oxybutynin, uses osmotic pressure to deliver the drug at a controlled rate over approximately 24 hours. It resembles a conventional tablet but has a two-part core consisting of a drug layer and below it, a "push" layer containing osmotically active components, the whole surrounded by a semipermeable membrane with a laser-drilled opening in the drug side. Water in the gastrointestinal tract enters the tablet and mixes with the drug to form a suspension. The "push" layer expands and pushes the suspended drug out of the orifice and into the gastrointestinal tract for eventual absorption. Pharmacokinetic studies have indicated a slow rise in mean plasma concentration of the isomer R-oxybutynin for 4 to 6 hours after a single dose of OROS oxybutynin, followed by maintenance of steady concentrations for up to 24 hours, minimizing the fluctuations between peak and trough associated with TID dosing of 5-mg immediate-release oxybutynin tablets. Efficacy and safety studies comparing the extended-release with the immediate-release formulation of oxybutynin demonstrated equivalent efficacy in patients with overactive urinary bladder. The adverse-event profile of oxybutynin is similar to that of a typical anticholinergic agent such as atropine--dry mouth, constipation, somnolence, blurred vision, headache, and gastrointestinal pain--although in 2 clinical studies, the incidence of dry mouth was less with the extended-release formulation. Once-daily dosing with OROS oxybutynin appears to be well tolerated and effective, as well as convenient, for the treatment of overactive bladder, particularly for elderly patients using multiple medications.

Paricalcitol, a new agent for the management of secondary hyperparathyroidism in patients undergoing chronic renal dialysis.

Patients with end-stage renal disease commonly develop secondary hyperparathyroidism. Calcitriol may be administered to such patients to decrease the synthesis and secretion of parathyroid hormone (PTH) and to help maintain calcium and phosphorus homeostasis. However, the doses of calcitriol required to suppress serum PTH concentrations can lead to hypercalcemia or hyperphosphatemia in many patients undergoing hemodialysis. Paricalcitol is a new vitamin D analogue that is safe and effective in suppressing elevated concentrations of PTH in patients with established hyperparathyroidism who are maintained on chronic hemodialysis. As with vitamin D, the biologic action of paricalcitol is mediated through activation of the vitamin D receptor (VDR). The VDR functions as a ligand-induced transcription factor regulating the rate of expression of genes that are involved in controlling not only calcium homeostasis and bone remodeling but also hormone secretion, inhibition of cell growth, and induction of cell differentiation. In vitro studies have shown that paricalcitol inhibits PTH secretion from bovine parathyroid cells in a dose-dependent manner. Studies in renally insufficient rats demonstrated that paricalcitol caused approximately 10 times less elevation of serum calcium concentrations than calcitriol. In clinical studies, paricalcitol effectively decreased PTH by about 60% over a 12-week period. Mean serum concentrations of calcium were significantly increased but remained within the normal range. There were occasional (5/414 determinations) transient elevations in serum calcium above the upper limit of normal in some (5/401) patients. Serum phosphorus values did not change significantly compared with baseline, although they tended to be slightly higher in the paricalcitol-treated group than in the group receiving placebo. Elevations of the calcium-times-phosphorus product were relatively few but occurred more often in the paricalcitol than in the placebo group. The terminal half-life of paricalcitol was 5 to 7 hours in healthy subjects; in patients undergoing hemodialysis, it was 14 hours. Adverse events associated with paricalcitol use included, among others, chills, feeling unwell, fever, sepsis, palpitations, dry mouth, gastrointestinal bleeding, nausea, vomiting, edema, light-headedness, and pneumonia. Paricalcitol should be considered as an alternative to calcitriol in the treatment of patients who are undergoing maintenance hemodialysis for end-stage renal disease, as it has a decreased potential to induce hypercalcemia and hyperphosphatemia. Additional studies are required to determine the long-term effects of therapy.

Trastuzumab, a recombinant DNA-derived humanized monoclonal antibody, a novel agent for the treatment of metastatic breast cancer.

Amplification of the human epidermal growth factor receptor 2 protein (HER2) in primary breast carcinomas has been shown to correlate with poor clinical prognosis for certain patients. Trastuzumab (Herceptin, Genentech, Inc., South San Francisco, California) is a highly purified recombinant DNA-derived humanized monoclonal immunoglobulin G1 kappa antibody that binds with high affinity and specificity to the extracellular domain of the HER2 receptor. In vitro and in vivo preclinical studies have shown that administration of trastuzumab alone or in combination with paclitaxel or carboplatin significantly inhibits the growth of breast tumor-derived cell lines that overexpress the HER2 gene product. At therapeutic doses in breast cancer patients, the mean half-life of trastuzumab is 5.8 days. Trastuzumab serum concentrations reach steady state with mean trough and peak concentrations of 79 microg/mL and 123 microg/mL, respectively. In a 222-patient, single-arm clinical study, treatment with a loading dose of trastuzumab 4 mg/kg administered IV followed by weekly IV doses of 2 mg/kg produced an overall response rate of 14% (2% complete remission and 12% partial remission). The beneficial effects were greatest in patients with the greatest degree (3+) of HER2 protein overexpression. In another clinical study, 469 women with metastatic breast carcinoma were randomized to a paclitaxel or anthracycline-plus-cyclophosphamide regimen with or without trastuzumab. The overall response rate was significantly greater in the trastuzumab-plus-chemotherapy group than in the chemotherapy-alone cohort. The magnitude of observed effects was greatest with pacli taxel plus trastuzumab. The most common adverse effects attributed to trastuzumab in clinical studies were fever and chills, pain, asthenia, nausea, vomiting, increased cough, diarrhea, headache, dyspnea, infection, rhinitis, and insomnia. Trastuzumab in combination with chemotherapy can lead to cardiotoxicity, leukopenia, anemia, diarrhea, abdominal pain, and infection. Trastuzumab has been approved by the US Food and Drug Administration as a single agent for the treatment of patients who have metastatic breast cancer involving overexpression of the HER2 protein and who have received 1 or more chemotherapy regimens; in combination with paclitaxel, it has been approved for the treatment of such patients who have not received chemotherapy.

Etanercept, a novel drug for the treatment of patients with severe, active rheumatoid arthritis.

The US adult rheumatoid arthritis (RA) population numbers approximately 2.1 million, with a greater proportion of cases in women. RA is a disease of the immune system that has no known cure, and current drugs do not affect the underlying cause. The side effects such drugs produce limit their usefulness, and many patients stop responding to these treatments over time. Etanercept, a biologic inflammation modulator, is a novel human recombinant version of the soluble p75 tumor necrosis factor (TNF) receptor that is linked to the Fc receptor of human immunoglobulin G subclass 1. It acts as a competitive inhibitor of the binding of TNF-alpha to cell-surface TNF receptors and thereby inhibits TNF-alpha-induced proinflammatory activity in the joints of RA patients. Etanercept acts as a cytokine "carrier" and TNF-alpha antagonist, rendering TNF-alpha biologically inactive, even though prolonging its half-life. In Phase I, II, and III clinical studies in patients with active, severe RA who had not responded to disease-modifying antirheumatic drug (DMARD) therapy, etanercept treatment decreased disease activity, increased functional activity, and improved health-related quality of life. In a recent 12-month continuation of an earlier 6-month study, 105 patients who received etanercept 25 mg subcutaneously twice weekly demonstrated rapid and sustained improvements in disease activity. The US Food and Drug Administration has approved etanercept for marketing for the treatment of moderately to severely active RA in patients who have not responded adequately to other DMARDs.

Leflunomide, a novel immunomodulator for the treatment of active rheumatoid arthritis.

Rheumatoid arthritis (RA) is a chronic disease affecting 0.8% of the population. Nonsteroidal anti-inflammatory drugs reduce the pain and inflammation of RA and improve mobility but do not slow the progression of joint damage. Disease-modifying antirheumatic drugs (DMARDs), which limit potentially irreversible joint damage, may influence the course of disease progression. This review describes the recently approved DMARD leflunomide, an isoxazole-based immunomodulator. Unlike other DMARDs, leflunomide arrests the growth of activated lymphocytes by inhibiting the enzyme dihydroorotate dehydrogenase, a critical link in the production of uridine monophosphate. Leflunomide is rapidly metabolized to the active major metabolite A77 1726, which is responsible for the drug's pharmacologic activity. Leflunomide has exerted inhibitory activity in animal models of RA. Its clinical efficacy has been demonstrated in a number of controlled trials. In two multinational 52-week studies and two 24-week studies, all leflunomide-treated patients received an initial loading dose of 100 mg for 3 days, followed by 20 mg/d. The effects on the signs and symptoms of RA were evaluated using the American College of Rheumatology (ACR) 20 responder index, tender and swollen joint counts and scores, patients' and physician's global assessments, and pain intensity index. Erosions and joint-space narrowing were assessed by radiography. Compared with placebo, leflunomide significantly improved the signs and symptoms of RA (41%-64% improvement) by ACR 20 responder criteria (P < 0.001). Leflunomide, methotrexate, and sulfasalazine were equally effective in terms of symptom outcomes. In terms of retarding the progression of disease, leflunomide was significantly superior to placebo, with no consistent difference from methotrexate or sulfasalazine. In a trial using a combination of leflunomide and methotrexate therapy, 53% of patients were responders by ACR 20 criteria. Adverse effects in RA patients receiving leflunomide included diarrhea, elevated liver enzymes, alopecia, and rash. Additional adverse events occurring with a frequency >5% included allergic reaction, asthenia, abdominal pain, back pain, and hypertension, among others. Thus leflunomide may be used in selected RA patients (ie, those starting RA therapy for the first time or failing earlier DMARD therapy). However, the product labeling requires monthly monitoring of liver enzymes until stable concentrations are reached. Other labeled warnings include a risk of immunosuppression and an increased risk of fetal death or teratogenic effects in pregnant women. Methotrexate, which is also hepatotoxic, is usually the initial DMARD recommended for use in patients with aggressive RA.

Safety and efficacy of sildenafil citrate in the treatment of male erectile dysfunction.

Sildenafil citrate, an oral therapy for erectile dysfunction, is a selective inhibitor of cyclic guanosine monophosphate (cGMP)-specific phosphodiesterase type 5 (PDE5), the predominant isozyme metabolizing cGMP in the corpus cavernosum. Chemically, it is a compound of the pyrazolo-pyrimidinyl-methylpiperazine class. Sildenafil has no direct relaxant effect on human corpus cavernosum but enhances the relaxant effect of nitric oxide (NO) on the corpus cavernosum by inhibiting PDE5, which is responsible for degradation of cGMP in this tissue. When sexual stimulation causes local release of NO, inhibition of PDE5 by sildenafil increases concentrations of cGMP in the corpus cavernosum, causing smooth muscle relaxation and blood flow into the penis, resulting in an erection. Sildenafil at recommended doses has no effect in the absence of sexual stimulation. The drug is rapidly absorbed after oral administration, with absolute bioavailability of 40%. Its pharmacokinetics are dose proportional over the recommended dosage range. Maximum plasma concentrations are reached within 30 to 120 minutes after oral dosing in the fasting state. Sildenafil is cleared predominantly by the hepatic microsomal isoenzymes CYP3A4 (major route) and CYP2C9 (minor route). Clinical studies assessed the effect of sildenafil on the ability of men with erectile dysfunction to engage in sexual activity and, specifically, to achieve and maintain an erection sufficient for satisfactory sexual intercourse. Sildenafil was evaluated at doses of 25, 50, and 100 mg in randomized, double-masked, placebo-controlled clinical trials of up to 6 months' duration. The drug was administered to hundreds of patients aged 19 to 87 years having erectile dysfunction of various etiologies for a mean duration of 5 years. Sildenafil was associated with statistically significant improvement in erectile function compared with placebo. Adverse effects reported at a rate of >2% were headache, flushing, dyspepsia, nasal congestion, urinary tract infection, abnormal vision, diarrhea, dizziness, and rash. No cases of priapism were reported. The use of sildenafil is contraindicated in men who are taking organic nitrates, because of the potential for a precipitous decrease in blood pressure. Postmarketing reports and surveillance have revealed at least 39 deaths with sildenafil use in men having a history of heart disease, men taking nitrate medications, and men in poor physical health due to lack of exercise. Many of the men who experienced serious adverse effects or death had a variety of concomitant diseases and were taking multiple medications.

The effects of topical S(+)-ibuprofen on interleukin-1 induced ocular inflammation in a rabbit model.

Topical non-steroidal anti-inflammatory drugs may serve as an alternative or adjunct to topical corticosteroid therapy for iritis. We have tested the efficacy of topically given S(+)-ibuprofen in a rabbit model of uveitis secondary to the intravitreal injection of human recombinant interleukin 1-alpha. Topically administered S(+)-ibuprofen was found to inhibit increased vascular permeability associated with this model. These results with topical S(+)-ibuprofen compare favorably to the results seen with topical prednisolone and are significantly superior to the results seen with topical flurbiprofen. Topical S(+)-ibuprofen did not significantly reduce the cellular infiltration associated with interleukin-1 induced inflammation. These findings suggest a potential role for topical S(+)-ibuprofen in the treatment of ocular inflammation and, in this animal model, it appears to be superior to an alternative non-steroidal compound, but further studies are indicated to assess its activity in alternate models of ocular inflammation.

Characterization of 5-[5-(4-chlorophenyl-2-furanyl)]dihydro-2(3H)-furanone as a nonsteroidal antiinflammatory drug.

5-[5-(4-Chlorophenyl-2-furanyl)]dihydro-2(3H)-furanone (F-1044), a nonsteroidal antiinflammatory drug related to orpanoxin, lacks the usual acid moiety of such agents. F-1044 had antiinflammatory activity equivalent to ibuprofen's and orpanoxin's in the carrageenin-induced paw edema model in normal and adrenalectomized rats. Antiinflammatory activity was also expressed in the guinea pig UV-induced erythema and rat established arthritis models. F-1044 was a more potent analgesic than ibuprofen and orpanoxin in the rat paw pressure assay. In contrast to the reference agents, F-1044 raised the pain threshold of both the yeast-injected and non-injected paws, suggesting a central component to its analgesic action. F-1044 was more potent than ibuprofen and orpanoxin in the rat brewer's yeast pyresis model. Based on its low activity in inhibiting bradykinin-induced bronchoconstriction in guinea pigs and low gastric irritation activity in rats. F-1044 appears to have a mechanisms of action that involves more than simple inhibition of prostaglandin synthesis. Thus F-1044 is a nonsteroidal antiinflammatory agent with unique chemical and pharmacological features.

Inflammatory responses to intradermal injection of platelet activating factor, histamine and prostaglandin E2 in healthy volunteers: a double blind investigation.

1. The local responses to intradermal injection of PAF, histamine and PGE2 were investigated in eight healthy male volunteers. Acute effects were monitored by weal and flare measurement; delayed effects were investigated by pain threshold testing and skinfold thickness measurements. 2. PAF and PGE2 were found to induce weal and flare responses which were clearly distinguishable from vehicle and dose related. 3. PAF was approximately 50 times as potent as PGE2 at inducing weal on a molar basis. 4. A dose related hyperalgesia was recorded in response to PGE2. No hyperalgesia could be demonstrated following PAF injection compared with vehicle. 5. PAF and histamine elicited an increase in skinfold thickness up to 2 h after injection which was distinguishable from vehicle.

Pharmacological evidence for a role of lipoxygenase products in platelet-activating factor (PAF)-induced hyperalgesia.

Platelet-activating factor (PAF), a potent inflammatory mediator, decreases the nociceptive threshold in the rat hindpaw. Pain sensitivity, measured by the applied pressure necessary to induce vocalization, was increased maximally at 3 and 4 hr after injection of synthetic PAF. The hyperalgesic response to PAF was specifically inhibited by agents that interfere with the lipoxygenase pathway of arachidonic acid metabolism and was not affected by cyclooxygenase inhibitors. BW-755C (3-30 mg/kg, p.o.) and L-615,919 (0.01-0.3 mg/kg, p.o.) significantly reduced PAF-induced hyperalgesia, whereas indomethacin had no effect. The finding that L-615,919, a specific 5-lipoxygenase inhibitor, was a potent inhibitor of this model of hyperalgesia leads to speculation that leukotrienes are important mediators of inflammatory pain.

2-[3-(1,1-Dimethylethyl)-5-methoxyphenyloxazolo[4,5-b]pyridine, a new topical antiinflammatory and analgesic compound lacking systemic activity and gastric side effects.

The substituted oxazolopyridine 2-[3-(1,1-dimethylethyl)-5-methoxyphenyl]oxazolo[4,5-b]pyridine (OZP) inhibits phorbol myristate acetate-induced increases in vascular permeability and neutrophil accumulation in rat ears with ED50 of 253 and 200 micrograms, respectively. This compound is as potent as indomethacin to inhibit UV-induced erythema in guinea pig skin and is an effective analgesic when applied topically to the rat footpad in the yeast hyperalgesia model. OZP is a cyclooxygenase inhibitor with an IC50 of 0.06 mumol/l and inhibits prostaglandin E2, but not leukotriene C4 synthesis, by mouse peritoneal macrophages. This compound is inactive in the carrageenan paw edema assay at 90 mg/kg when administered orally or intraperitoneally, but is effective when injected into the paw. OZP is not a contact allergen and does not cause gastric irritation in rats at doses up to 180 mg/kg orally. OZP is rapidly metabolized by rat liver microsomes in a concentration and time dependent manner. Furthermore, when administered orally, OZP is cleared rapidly in rats with plasma levels being detected only at 5 and 30 min following a 2 mg/kg dose. There was no drug in the gastrointestinal tract of rats 3 h after an oral dose. Thus, this compound appears to be a new, potent and safe topical antiinflammatory and an analgesic agent lacking systemic effects.

A pharmacologic analysis of the action of platelet-activating factor in the induction of hindpaw edema in the rat.

Platelet-activating factor (PAF), a phospholipid product of neutrophils, alveolar macrophages, monocytes, and platelets and an important mediator of inflammatory reactions, was studied for its ability to evoke hindpaw edema in the rat. PAF caused edema, peaking at 1 hr and gradually declining over the next 2 hr. The H1 and H2 antihistamines, mepyramine and cimetidine, the serotonin/histamine antagonist, cyproheptadine, and the serotonin antagonist, methysergide, were ineffective in reducing PAF-induced paw edema. Indomethacin, acetylsalicylic acid, and dexamethasone did not inhibit the peak edematous response but significant reduction was noted with only dexamethasone at 3 hr. Prazosin and propranolol did not prevent PAF-induced edema, whereas, yohimbine, phentolamine, rauwolscine, verapamil and theophylline partially inhibited edema. Clonidine and guanfacine did not induce edema when injected into the rat hindpaw. These results suggest that PAF elicits edema at vascular sites of the rat hindpaw which are partially dependent on extracellular Ca2+ movement, are not due to alpha-1 or alpha-2-adrenoreceptor stimulation, histamine, serotonin, or prostaglandin activity, and demonstrates variable sensitivities to agents blocking Ca2+ entry. Inhibition of specific PAF-sensitive receptors await the discovery of specific PAF antagonists.

2,3-dihydro-4H-1-benzopyran-4-one O-carbamoyloximes, a series of gastric antisecretory agents.

A series of 2,3-dihydro-4H-1-benzopyran-4-one O-carbamoyloximes were synthesized and evaluated for gastric antisecretory activity in a pylorus-ligated rat model. Various substituents in the 6-position did not afford any compounds more active than I.

The effect of leukotriene D4 on the isolated stomach and colon of the rat.

The effect of synthetic leukotriene D4 (LTD4) was evaluated on isolated gastric longitudinal or circular smooth muscle and distal colon of the rat. The concentrations of LTD4, 2.5 X 10(-10)M to 5 X 10(-7)M, evoked minimal to maximal contractile responses. In addition, selected prostaglandins were used to identify the mediator of LTD4-induced contraction of gastric smooth muscle. FPL 55712 inhibited LTD4-induced contractions of gastric longitudinal or circular muscle. Indomethacin inhibited only LTD4-induced contractions of the longitudinal muscle. A combination of FPL 55712 and indomethacin produced greater inhibition of LTD4-induced contractions of longitudinal muscle than either agent alone. However, the same combination of inhibitors showed no greater effect than FPL 55712 alone on LTD4-induced contractions of circular smooth muscle. Unlike PGI2, PGF2, PGA2, or PGD2, PGE2 evoked contraction of the longitudinal muscle and relaxation of the circular muscle of the stomach. The dissimilar effect of PGE2 in the two smooth muscle layers of the rat stomach may signify that PGE2 is the prostaglandin released by LTD4 from the longitudinal and circular gastric muscle. However, the opposing pharmacologic effects following LTD4-induced release of prostaglandins in the circular muscle of the stomach would preclude the appearance of an inhibitory effect of indomethacin in this tissue. In contrast, PGE2 and other prostaglandins contract gastric longitudinal muscle in response to LTD4. Thus, these studies clearly suggest that LTD4 has both a direct and indirect effect on gastric smooth muscle of the rat. Unlike the stomach, LTD4-induced contraction of the distal colon was not inhibited by indomethacin while FPL 55712 antagonized contractions. Thus, these findings indicate a differential mechanism of stimulation of rat gastrointestinal tissue by LTD4.

The effect of calcium antagonists on contractions of the sensitized and normal guinea pig ileum.

The purpose of this study was to learn whether a number of Ca2+ antagonists were effective in reducing contractile responses of the isolated ileum of the sensitized and normal guinea pig. Contractions of the normal ileum in response to LTD4, acetylcholine, histamine, and potassium chloride were obtained before and after verapamil, diltiazem and papaverine. Ovalbumin-induced contractions of the ovalbumin-sensitized ileum were obtained in the presence of the three Ca2+ antagonists. In the normal ileum, all the Ca2+ antagonists were highly effective in diminishing the contractile responses to LTD4, acetylcholine, histamine and potassium chloride. In the sensitized ileum, ovalbumin-evoked contractions, with subsequent release of a potent contractile mediator (presumably SRS-A), were Ca2+-dependent since verapamil, diltiazem and papaverine caused a concentration-related reduction of contractions. Thus, the influx of extracellular Ca2+ plays a key role in the contractile responses of the normal and sensitized guinea pig ileum when stimulated by various potent agonists acting on specific receptors or on the cell membrane.

Inhibition of guinea pig gastric microsomal potassium-stimulated ATPase by nolinium bromide.

Although nolinium bromide (NB) [2-(3,4-dichlorophenylamino)-quinolizinium bromide] inhibited histamine-stimulated acid secretion in vivo in the pylorus-ligated guinea pig, no inhibition of basal or histamine-stimulated acid secretion from the isolated guinea pig gastric fundic disk was observed at serosal or mucosal concentrations from 0.1 to 200 microM. NB did not inhibit carbonic anhydrase in whole stomach homogenates of guinea pig, but did inhibit the potassium-stimulated gastric microsomal ATPase. The IC50 value (compound concentration giving 50% inhibition of the rate of ATP hydrolysis) for the net stimulated reaction (activity with KCl minus activity without KCl) was 65 microM (95% confidence limits = 42-101 microM). The basal reaction (no added KCl) was not inhibited. Inhibition of ATPase by NB was not due to its bromide ion, since NaBr did not, while the chloride analog of NB did, inhibit the enzyme. It was concluded that NB has no direct histamine-H2 receptor blocking activity. Whether ATPase inhibition contributes to its gastric acid antisecretory property is uncertain because of the lack of inhibitory activity in the isolated gastric disk assay.

2-Bromo-1-hydroxyquinolizinium bromide substituted anilinium salts: a new class of anti-inflammatory agents.

A series of 2-bromo-1-hydroxyquinolizinium bromide substituted anilinium salts have been prepared by reaction of 1-acetoxy-2-bromoquinolizinium bromide with an appropriately substituted aniline. The resulting anilinium derivatives exhibited a moderate to high degree of anti-inflammatory activity in the carrageenin-induced rat paw edema assay. The most active anilinium salt of the series was evaluated for antiarthritic activity in the adjuvant induced arthritis rat model.