The postantibiotic suppressive effect of L-ofloxacin, an optically active isomer of ofloxacin.

The postantibiotic suppressive effect (PAE) of L-ofloxacin was studied and compared with those of ciprofloxacin and norfloxacin. The PAE of L-ofloxacin was observed against all Gram-positive organisms tested: Staphylococcus aureus, S. epidermidis, and Enterococcus faecalis. At the achievable serum concentrations L-ofloxacin showed a longer PAE than ciprofloxacin and norfloxacin. Exposure of organisms to 4 micrograms/ml of L-ofloxacin for 2 hr produced a 3.1 and 4.2 hr PAE for methicillin-sensitive and methicillin-resistant staphylococci, respectively. Against E. faecalis and S. epidermidis, the PAEs of L-ofloxacin were 1.9 and 1.6 hr, respectively.

Bronchodilator and antiallergic effects of thiazinamium chloride in guinea pigs, rats, cats and dogs.

This study characterized the in vivo pulmonary pharmacology of thiazinamium chloride administered largely by the aerosol route in different animal species. The compound has greater anticholinergic but weaker antihistaminic activity than promethazine, the parent compound. It was less potent than atropine or ipratropium as an anticholinergic and had a shorter duration of action, but unlike these compounds it had long-lasting antihistaminic activity. It is effective in both IgG- and IgE-induced models of passive lung anaphylaxis in guinea pigs and rats, respectively. In Ascaris-induced allergic asthma in the conscious dog it produced a dose-related inhibition of the antigen-induced bronchospasm. No major side effects were observed in acute oral and inhalation toxicity studies in guinea pigs or rhesus monkeys. The results demonstrate that thiazinamium chloride is a safe, potent and efficacious bronchodilator after aerosol administration, with a rapid onset and moderate duration of action in animal models.

Antigastrolesive, gastric antisecretory, diarrheagenic and mucus-stimulating effects in rats following topically applied rioprostil, a synthetic prostaglandin E1 analog.

Prostaglandins may have many biological actions including hypotensive and antipeptic ulcer activity. The purpose of this investigation was to determine if the primary alcohol prostaglandin E1 analog rioprostil1 prevents ethanol-induced gastric lesions (antigastrolesive activity), inhibits gastric acid secretion (antisecretory activity), or causes diarrhea in rats when administered topically, and to compare these responses to the effect of rioprostil following enteral (oral or intraduodenal) administration. Rioprostil exhibited antigastrolesive activity in rats when administered either orally or when applied topically. The topical antigastrolesive potency of rioprostil against ethanol-induced lesions [ED50 = 3.7 (0.5-12) micrograms/kg] was similar to its oral potency [ED50 = 1.9 (1.7-2.2) micrograms/kg]. In 4 hr pylorus-ligated rats, topically administered rioprostil inhibited total gastric acid output with a potency [ED50 = 5.1 (2.6-24) mg/kg] similar to intraduodenal administration [ED50 = 3.7 (2.8-5.3) mg/kg]. In addition, in these rats rioprostil increased mucin levels and did not cause dermal irritation. Finally, the incidence of diarrhea was lower when rioprostil was applied topically than when given orally with a 16-fold difference in potency between these two routes of administration. These data show that when rioprostil is applied via the skin it has antigastrolesive, gastric antisecretory and mucus stimulatory effects in rats equal to enteral administration, and a diarrheagenic potency lower than following oral administration. This profile suggests that topical administration of rioprostil may be a useful means of delivery for clinical treatment of peptic ulcer disease.

Antifertility activity and general pharmacological properties of ORF 13811: a synthetic analog of zoapatanol.

ORF 13811, a synthetic analog of zoapatanol, was evaluated in a variety of in vivo and in vitro biological test systems to determine antifertility and uterotonic activity as well as its general pharmacological profile. ORF 13811 is a potent antifertility agent after oral administration in a number of animal species including mice, rats, guinea pigs, dogs and baboons. The single oral ED50 for contragestational activity in the pregnant guinea pig (day 22), mouse (day 16) and rat (day 16) is in the range of 6 to 10 mg/kg. In pregnant beagle dogs, a dose-related contragestational effect was obtained within several days after oral administration of ORF 13811 in the dosage range of 10 to 30 mg/kg. ORF 13811, when administered to pregnant baboons, caused dose-related vaginal bleeding and evacuation of uterine contents within 3 days following treatment with oral doses of 40 to 60 mg/kg. Serum progesterone levels were decreased in baboons and the degree of reduction correlated with contragestational activity. ORF 13811 was also effective in inhibiting implantation in mice, rats and hamsters, but required higher dose levels than those of the post-implantive treatments. In vitro uterotonic properties of ORF 13811 were demonstrated by its ability to induce contraction of uterine strips obtained from female guinea pigs at two different reproductive stages (day 15 of the estrous cycle and day 22 of pregnancy). In these preparations ORF 13811 was approximately 1/30 to 1/50th as potent as PGF2 alpha. In a series of pharmacological tests, ORF 13811 was found to possess slight sedative properties but was devoid of activity on pulmonary, gastrointestinal, and immune systems as well as in a number of biochemical tests, data not reported here. However, in cardiovascular studies, ORF 13811 appears to possess a vasoconstrictor profile in the dog, monkey and baboon as indicated by an increase in mean arterial blood pressure as well as total peripheral and regional vascular resistances. The in vitro pharmacological profile of ORF 13811 was examined in myocardial tissue and vascular smooth muscle test systems and compared to PGF2 alpha. ORF 13811 was found to contract rat aortic strips, 15 times less potent than PGF2 alpha. The compound had no direct effect on isolated guinea pig atria or papillary muscle. In summary, ORF 13811 is a potent orally active antifertility agent characterized primarily as a contractor of uterine and vascular smooth muscle.

Gastric antisecretory and antigastrolesive pharmacology of rioprostil.

Rioprostil, a primary alcohol prostaglandin E1 analogue, inhibits gastric acid secretion, both in vivo and in vitro, and prevents the formation of experimentally-induced gastric lesions in rats and dogs. In vitro experimental evidence suggests that the mechanism of the gastric antisecretory activity of rioprostil involves inhibition of the membrane bound histamine-stimulated adenylate cyclase. In vivo, rioprostil inhibits gastric acid secretion in 4-h pylorus-ligated rats, in gastric fistula dogs stimulated by betazole, tetragastrin, bethanechol, or 2-deoxy-D-glucose, and in Heidenhain pouch dogs stimulated by food. Rioprostil can completely prevent macroscopically visible gastric lesions induced by a variety of noxious agents in rats, including 50% ethanol, aspirin, indomethacin, strong acid, strong base and hypertonic saline. In dogs, rioprostil, but not the H2-blockers cimetidine or ranitidine, totally prevents endoscopically visible gastric lesions induced by aspirin tablets or 60% ethanol, and accelerates the healing of established aspirin-induced gastric lesions from 20 days (vehicle control) to 6 days (33 micrograms/kg p.o., t.i.d.) or 11 days (3 micrograms/kg p.o., t.i.d.). The precise mechanism for the antigastrolesive activity of rioprostil is not known, but may involve increased mucus and bicarbonate secretion, maintaining or increasing gastric mucosal blood flow, increasing the rate of cellular restitution, or possibly antigastrin activity that has been demonstrated in dogs. In rats, rioprostil also prevents duodenal lesions induced by cysteamine, small intestinal lesions induced by indomethacin, and colonic lesions induced by ethanol. The antisecretory and antigastrolesive potency of rioprostil given transdermally to rats is similar to its potency when given systemically, although its diarrhoeagenic potential is lower when given topically compared to oral administration. When used in combination with several non-steroidal anti-inflammatory drugs (NSAIDs) in a model of arthritis in rats, rioprostil inhibits gastric lesion formation without interfering with the anti-inflammatory or analgesic potency of the NSAIDs. In addition, concomitant use of either antacid or cimetidine with rioprostil does not inhibit either the antisecretory or antigastrolesive potency of rioprostil, with the effect of the combination being additive. The doses required to inhibit formation of experimentally-induced gastric lesions in both rat and dog are lower than those required to inhibit gastric acid secretion. This separation of antigastrolesive from antisecretory activity distinguishes rioprostil from other non-prostanoid antisecretory agents, such as histamine H2- receptor antagonists, and establishes rioprostil as a 'selective antigastrolesive agent' (SAGA).(ABSTRACT TRUNCATED AT 400 WORDS)

Adjuvant arthritis: immunopathological and hyperalgesic features.

Adjuvant arthritis is an experimental immunopathy that is thought to share many features of human rheumatoid arthritis and, as such, is one of the most widely used models for studying the anti-inflammatory properties of compounds. Adjuvant arthritis can be induced in the rat by the injection of various bacterial cell walls or their components; however, the exact immunogen remains unknown. Recently, an autoantibody response to type II collagen was described not only in the collagen-induced arthritic model but in the adjuvant-induced disease as well. This response thus suggests that shared antigenic determinants exist between type II collagen and the responsible immunogen in the bacterial cell wall components. The contribution of the T lymphocyte to the pathogenesis of adjuvant arthritis is well known. It has now been shown that under specific conditions, adjuvant arthritis can be either enhanced or suppressed with pharmacologic or surgical manipulation, thus suggesting the heterogenicity of T lymphocytes capable of influencing the course of the disease. Levamisole was shown to reverse the augmentation of adjuvant disease seen after adult thymectomy, which suggests that levamisole can restore an aberrant immune response. Monoclonal antibodies are now being developed to evaluate T cell subsets in the rat. The use of these antibodies to study or selectively deplete lymphocyte subpopulations in this disease model promises to reveal immunologic characteristics that may lead to the development of new classes of immunoregulant drugs. Finally, the adjuvant rat has been found useful as a pain model capable of detecting the analgesic properties of both central and the newer peripheral analgesics. The above studies further corroborate the similarities between the immunopathological and hyperalgesic features of human rheumatoid arthritis and adjuvant disease. Recently developed immunologic technology may allow a new look at an old model and may result in the ability to evaluate new classes of immunoregulating agents.

Potent and selective effects of suprofen on uterine prostaglandin synthesis.

Suprofen is a non-narcotic, peripheral analgesic that exhibits potent prostaglandin (PG) synthesis inhibitory activities in a variety of subcellular tissue preparations and in vivo. The results of the present study show suprofen to be significantly more potent than either ibuprofen (6-fold) or aspirin (1000-fold) as an inhibitor of PG production by cell-free preparations of guinea pig uteri. It is selectively more potent against the production of PGF2 alpha and PGE2 than against the formation of 6-keto PGF1 alpha, the stable metabolite of prostacyclin. Suprofen is markedly more potent inhibiting the conversion of arachidonic acid to PGF2 alpha than is ibuprofen (30 times) or aspirin (1250 times). Taken together with the important role PGF2 alpha plays in the etiology of dysmenorrhea and the observation (Hahn et al., 1982) that suprofen is more potent and effective than a number of other PG synthesis inhibitors, including ibuprofen and aspirin, at reducing in vivo guinea pig uterine contractions induced by arachidonic acid, the results of the present study suggest a mechanism to support the clinical findings that suprofen is a very effective treatment for the signs and symptoms of dysmenorrhea.

Animal pharmacology of Wy-16,225, a new analgesic agent.

The analgesic potency of Wy-16,225 in rodents and primates is greater than morphine while antagonist potency is slightly less than that of nalorphine. The compound demonstrates properties unlike those of standard narcotic and narcotic antagonist agents and has a wide margin of safety. In dependence liability studies, Wy-16,225 neither acutely substitutes for morphine nor produces direct dependence when administered chronically to monkeys. Wy-16,225 has no anti-inflammatory properties, is not constipating in rats, has no significant cardiovascular toxicity in dogs and produces minimal respiratory depression in monkeys.

Suprofen, a new peripheral analgesic.

The antinociceptive properties of suprofen [alpha-methyl-4-(thienylcarbonyl)benzene acetic acid] are described in a pathologically induced hyperalgesic model, the rat adjuvant arthritis flexion test. By using this assay, suprofen was characterized as an orally effective, non-narcotic analgesic with a rapid onset and 4-hr duration of activity. Suprofen is 50 times more potent than acetaminophen, five times more potent than codeine and equipotent to the new peripheral analgesics, zomepirac and diflunisal. In combination experiments, suprofen potentiates the analgesic effects of acetaminophen and, unlike morphine, the analgesic effect of suprofen is not blocked by naloxone. In other hyperalgesic assays, suprofen is an extremely potent inhibitor of arachidonate-induced writhing and is equipotent to morphine in the yeast-induced paw edema (Randall-Selitto) assay. Additionally, suprofen is inactive on the normal paw in the Randall-Selitto test, the mouse Eddy hot-plate test and the tail withdrawal reflex assay induced by warm water in rats, all sensitive tests capable of detecting central (narcotic) but not peripheral analgesics. Activity on prostaglandin biosynthesis from several species and tissues suggests that suprofen is a tissue selective inhibitor of prostaglandin synthesis. These experiments suggest that suprofen represents a new class of potent, orally effective, peripheral (non-narcotic) analgesics with potential usefulness in a variety of clinical pain situations formerly reserved for narcotics.

Introduction to the pharmacology of suprofen.

A number of peripherally acting analgesics have become available in the past two decades for the treatment of mild to moderate pain of diverse etiology. The action of these agents is based on their putative ability to inhibit prostaglandin biosynthesis and attenuate hyperalgesia. Suprofen is a new and potent peripherally acting analgesic with anti-inflammatory and antipyretic properties which appears to inhibit prostaglandin synthetase in a tissue-selective manner. In preclinical studies, suprofen was shown to possess a wide separation of analgesic activity from gastrointestinal irritation. Suprofen appears to exert its pharmacological effect by inhibiting synthesis of prostaglandins from precursor arachidonic acid, inhibiting the pain induced by bradykinin, and by raising the threshold to pain induced by prostaglandins. The onset of action is rapid with peak analgesic effect reached in 1-2 h. Preclinical data suggest that suprofen may be an extremely valuable and versatile analgesic for the clinical management of pain.

Actions of prostaglandins on the respiratory tract of animals.

Experimental data now strongly suggest that the PGs, by nature of their natural local occurrence and destruction, powerful effects on, and release from lung tissue are important in regulating both pulmonary homeostasis and dysfunction. Laboratory studies on their activity, potency, duration, preferred route of administration, mechanism and possible antiallergic effects, have been largely substantiated in humans. Structure activity studies on a large number of congeners of PGE, PGF, and PGA emphasize the critical importance of stereochemistry and various substituent groups on biologic activity in the lung.

The antialgesic drugs: human therapeutic correlates of their potency in laboratory animal models of hyperalgesia.

This survey discusses the correlation between the oral potency of antialgesic drugs in several pharmacology laboratories and their human oral dose in clinical practice. We also present a brief overview of a few biological assays that have been successfully used to direct the synthesis of newer antialgesic drugs. The laboratory assay that our analysis showed to be most predictive of the clinical analgesic dose is based upon the response of rats to flexion of an arthritic joint. Laboratory ED50 values from the ACh-induced abdominal constriction assay in mice are nearly as predictive while the predictive power of the yeast-induced hyperalgesia assay in rats is somewhat less. Probably because of the small number of experiments, the correlation between the efficacy of these agents in a canine model of synovitis and their clinical doses only reached borderline statistical significance (p = 0.0651). Regression equations are presented that permit calculations of single clinical analgesic doses from efficacy data in individual tests. Calculation of stepwise multiple regression showed that the clinical dose could be best predicted when efficacy data obtained in the joint flexion assay in rats and the ACh-induced constriction assay in mice are both taken into account. We have concluded that the effective doses are highly predictive of clinical efficacy because these animal assays have been designed to reflect the action of drugs upon prostanoid-induced hyperalgesia.

Selective gastric antilesion properties of rioprostil, a prostaglandin E1 analog, in rats and dogs.

This paper characterizes the ability of rioprostil, a synthetic primary alcohol prostaglandin E1 analog, to inhibit gastric acid secretion and prevent experimentally induced gastric lesions in rats and dogs, and determines the selectivity (the separation in potency) for these effects. In 4-hr pylorus ligated rats, rioprostil inhibited gastric acid output when administered i.v., s.c., p.o. or intraduodenally, with ED50 values of 0.9, 1.8, 2.9 and 3.7 mg/kg, respectively. Rioprostil suppressed meal-stimulated acid output in Heidenhain pouch dogs and inhibited gastric acid output stimulated by tetragastrin, 2-deoxy-D-glucose, betazole or bethanechol in gastric fistula dogs with ED50 values of 7, 10, 16 and 17 micrograms/kg p.o., respectively. These values in dogs were not significantly different from each other, suggesting that the mechanism of the antisecretory effect of rioprostil is similar regardless of the secretagogue used. Rioprostil prevented ethanol induced gastric lesions in rats (ED50 = 1.5 micrograms/kg p.o.; 12.0 micrograms/kg s.c.) after a 30-min pretreatment. The 8-fold difference in potency between the p.o. and s.c. routes may reflect a local component in the antilesion mechanism of rioprostil. In dogs, rioprostil inhibited aspirin-induced gastric lesions with a p.o. ED50 of 1.6 micrograms/kg. Maximum antilesion activity in dogs for cimetidine or ranitidine was less than 50%, whereas rioprostil inhibited lesion formation by 100% without the appearance of side effects. Oral antilesion selectivity of rioprostil in rats (antisecretory ED50/antilesion ED50) was nearly 2000-fold using the optimum pretreatment time (30 min), and was 12-fold when the pretreatment time (4 hr) was the same as the duration of the antisecretory assay.(ABSTRACT TRUNCATED AT 250 WORDS)