Daily application of alprostadil topical cream (Vitaros) does not impact vaginal pH, flora, or histology in female cynomolgus monkeys.

Topical alprostadil cream (Vitaros) is approved in Canada and Europe for the treatment of erectile dysfunction. To determine the effects on the female urogenital tract with repeated administration of the entire dose (300 µg alprostadil containing 2.5% dodecyl-2-n,n-dimethylaminopropionate hydrochloride), the vaginal pH, flora, and histology were assessed as a model for 100% transference from male to the female during unprotected sexual intercourse. Female cynomolgus monkeys were administered the entire dose of Vitaros for 14 days with a 7-day recovery. Relative to vehicle and placebo cream, the vaginal pH and microflora were determined at baseline and weekly, thereafter. Vaginal biopsies were evaluated at the end of dosing and recovery. All animals were clinically normal for the study duration, and the vaginal pH was consistent between dose groups and the dosing period. Vaginal microflora and histopathology findings of mild inflammation were generally similar across treatment groups. In conclusion, repeated vaginal exposure to Vitaros did not alter the pH, microflora, or histology after 14 daily doses, supporting the safety of Vitaros transference to the female partner.

Comparison of prostaglandin E1- and prostaglandin E2-induced hyperalgesia in the rat.

We have studied prostaglandin E1-induced mechanical hyperalgesia in the rat hindpaw, by assessing paw-withdrawal thresholds, before and after injecting prostaglandin E1 alone or with other agents, in normal and streptozotocin-induced diabetic rats. In normal and diabetic rats, prostaglandin E1 (1-1000 ng) produced a dose-dependent decrease in mechanical nociceptive threshold. In diabetic rats, prostaglandin E1 was more potent than in normal rats, in producing hyperalgesia, whereas prostaglandin E2 hyperalgesia was not changed in normal and diabetic rats. Prostaglandin E1-induced hyperalgesia was not inhibited by E-type 1 prostaglandin receptor antagonists, SC19220 or SC51089, either in normal or diabetic rats. In fact, in the presence of SC19220, prostaglandin E1 produced enhanced hyperalgesia, in normal rats. Prostaglandin E1 hyperalgesia was not significantly modified by sympathectomy or indomethacin. Unlike prostaglandin E2, prostaglandin E1 hyperalgesia was not blocked by the inhibitor of the stimulatory guanine nucleotide-binding regulatory protein, guanosine 5'-O-(2-thiodiphosphate). It is suggested that prostaglandin E1 decreases primary afferent nociceptive threshold directly, by activating a prostaglandin receptor other than the E-type 1 prostaglandin receptor, and that this receptor is not coupled to a stimulatory guanine nucleotide-binding regulatory protein.

Aspartic and glutamic acids increase in the frontal cortex during prostaglandin E1 hyperthermia.

The aim of the present experiment was to evaluate the role played by aspartic acid and glutamic acid of frontal cerebral cortex during the hyperthermia induced by prostaglandin E1. Two groups of six Sprague Dawley male rats were anaesthetized with ethyl-urethane. The frontal cortical concentrations of aspartic and glutamic acids, the firing rate of the sympathetic nerves to the interscapular brown adipose tissue, the colonic and interscapular brown adipose tissue temperatures were monitored both before and after an intracerebroventricular injection of prostaglandin E1 (500 ng) or saline. Aspartic and glutamic acids were collected using a microdialysis probe placed in the frontal cortex. Concentrations of aspartic and glutamic acids were measured by high-pressure liquid chromatography with fluorescence detector. Prostaglandin E1 induced an increase in the concentrations of aspartic and glutamic acids, in the firing rate of sympathetic nerves and in the colonic and interscapular brown adipose tissue temperatures. The findings of the present experiment indicate that an intracerebroventricular injection of prostaglandin E1 causes release of aspartic and glutamic acids in the frontal cortex.

Prostaglandins act as neurotoxin for differentiated neuroblastoma cells in culture and increase levels of ubiquitin and beta-amyloid.

Although chronic inflammatory reactions have been proposed to cause neuronal degeneration associated with Alzheimer's disease (AD), the role of prostaglandins (PGs), one of the secretory products of inflammatory reactions, in degeneration of nerve cells has not been studied. Our initial observation that PGE1-induced differentiated neuroblastoma (NB) cells degenerate in vitro more rapidly than those induced by RO20-1724, an inhibitor of cyclic nucleotide phosphodiesterase, has led us to postulate that PGs act as a neurotoxin. This study has further investigated the effects of PGs on differentiated NB cells in culture. Results showed that PGA1 was more effective than PGE1 in causing degeneration of differentiated NB cells as shown by the cytoplasmic vacuolation and fragmentation of soma, nuclei, and neurites. Because increased levels of ubiquitin and beta-amyloid have been implicated in causing neuronal degeneration, we studied the effects of PGs on the levels of these proteins during degeneration of NB cells in vitro by an immunostaining technique, using primary antibodies to ubiquitin and beta-amyloid. Results showed that PGs increased the intracellular levels of ubiquitin and beta-amyloid prior to degeneration, whereas the degenerated NB cells had negligible levels of these proteins. These data suggest that PGs act as external neurotoxic signals which increase levels of ubiquitin and beta-amyloid that represent one of the intracellular signals for initiating degeneration of nerve cells.

Effects of tetramethylpyrazine on prostaglandin E(2)- and prostaglandin E(2) receptor agonist-induced disruption of blood-aqueous barrier in pigmented rabbits.

PURPOSE: To evaluate the effect of tetramethylpyrazine on the elevation of aqueous flare and intraocular pressure (IOP) induced by prostaglandin (PG) E(2) and PGE(2) receptor (EP) agonists. METHODS: PGE(2) or EP agonists (11-deoxy PGE(1), EP(2) agonist; 17-phenyl trinor PGE(2), EP(1) and EP(3) agonist; or sulprostone, EP(1) and EP(3) agonist), 25 microg/mL, were transcorneally administered to pigmented rabbits. Animals were pretreated with tetramethylpyrazine intravenously (10 or 30 mg/kg) or topically (0.1% solution). Aqueous flare was measured using a laser flare-cell meter, and the intensity was expressed as the area under the curve (AUC). Intraocular pressure was measured using a noncontact tonometer. RESULTS: After administration of PGE(2), aqueous flare and IOP increased and then gradually decreased. The AUC of eyes pretreated with tetramethylpyrazine, 10 or 30 mg/kg, intravenously, or topical 0.1% solution, was significantly smaller than that of the controls. The mean Delta IOP of eyes pretreated with tetramethylpyrazine, 30 mg/kg intravenously, was significantly lower than that of the controls. After administration of 11-deoxy PGE(1), aqueous flare increased and then gradually decreased. 17-phenyl trinor PGE(2) and sulprostone did not disrupt the blood-aqueous barrier. The AUC of eyes pretreated with tetramethylpyrazine, 10 or 30 mg/kg, intravenously, before 11-deoxy PGE(1) application was significantly smaller than that of the controls. CONCLUSION: The results indicated that tetramethylpyrazine inhibited PGE(2)- or 11-deoxy PGE(1)-induced elevation of aqueous flare and IOP.

[Effects of hypotensive anesthesia with prostaglandin E1 or trimethaphan on renal microstructure].

A study was made on the presence or absence and the degree of histopathological renal cell damage, in hypotensive anesthesia models with prostaglandin E1 (PGE1) or trimethaphan. Cell damage was most noticeable in the S3 segment, the straight and second half part of the proximal renal tubule. The lesion was evaluated and semiquantified. The trimethaphan group in this area exhibited degeneration--including cell vacuolation and granule increase in this site, as well as cytoclasis such as cell fragments in the lumen, luminal extension, flattening of epithelial cell and damage of distal renal tubular columns. In the PGE1 group, cell degeneration was milder than in the trimethaphan group, and there were no cytoclasis findings. Renal cell damage in the PGE1 group was slighter than in the trimethaphan group.

Toxicity of prolonged high dose inhaled PGE1 in ventilated neonatal pigs.

OBJECTIVE: To study the toxicity of inhaled PGE1 (IPGE1) in healthy ventilated piglets. METHODS: Mechanically ventilated anesthetized piglets received either high dose IPGE1 (IPGE1 group) or nebulized saline (control group) continuously for 24h. Cardio-respiratory parameters, complete blood counts and serum electrolytes were monitored. Lung histology was evaluated by a masked pathologist for the severity (minimal, moderate, and severe) and extent (focal, multifocal, and diffuse) of histologic injury. RESULTS: Ten neonatal pigs were instrumented. Four received nebulized saline and six received high dose IPGE1. There was no evidence of adverse cardio-respiratory effects, bronchial irritation or hypernatremia related to IPGE1. Diffuse/multifocal alveolar edema and focal polymorphonuclear infiltration was observed in both the control and IPGE1 groups suggesting that alveolar alterations may be secondary to effects of mechanical ventilation. The most distinct histomorphological abnormalities observed in the IPGE1 animals were focal ulceration, flattening of the bronchial epithelium and loss of cilia of moderate to severe degree in the trachea and bronchi. CONCLUSION: In healthy piglets, inhalation of high dose IPGE1 was not associated with adverse cardiorespiratory effects, bronchial irritation, or hypernatremia and produced minimal signs of pulmonary toxicity even after 24h. Prolonged inhalation of high dose PGE1 therefore appears safe in newborn piglets.

Clinical application of prostaglandin E1 in cases of occlusive arterial disease.

For the present time, intraarterial infusion of PGE1 is the treatment of choice for impending gangrene. But because of its technical difficulties and unpleasant side effects, mentioned earlier, intravenous administration of PGE1 should be considered in some cases.

Biological activity of prostaglandin E3 with regard to oedema formation in mice.

The biological activity of PGE3 with regard to oedema formation in mice was examined. Paw swelling was measured 30 minutes after injection of 10 microliters PGE2 or PGE3 into the plantar region of the hind paw. Doses investigated ranged from 1 ng-10 micrograms. Both PGE2 and PGE3 had substantial oedemogenic activity in this system.

Two-year evaluation of misoprostol for carcinogenicity in CD Sprague-Dawley rats.

The carcinogenic potential of misoprostol, a synthetic prostaglandin E1 analogue with anti-ulcer potential, was evaluated in CD Sprague-Dawley rats. The compound was given daily by gavage at 24, 240, and 2,400 micrograms/kg, up to 150 times the daily human dose for 2 years. Necropsies were done on all animals and the incidences of non-neoplastic and neoplastic changes analyzed for significance by life table methods. The only statistically significant non-neoplastic finding was epithelial hyperplasia and hyperkeratosis of the gastric mucosa. These changes, which are characteristic of some prostaglandins, were expected. Other non-neoplastic findings were typical of known spontaneous conditions in this strain of rats. The most frequent neoplasm was the pituitary adenoma, followed by the mammary fibroadenoma, mammary adenoma, mammary adenocarcinoma, and thyroid C-cell adenoma. A rare neoplasm, squamous cell carcinoma of the ovary was found in two rats. There was no evidence that misoprostol is carcinogenic for CD Sprague-Dawley rats.

Twenty-one-month evaluation of misoprostol for carcinogenicity in CD-1 mice.

Misoprostol, a synthetic prostaglandin E1 methyl ester analogue with anti-ulcer potential, was evaluated for its carcinogenic potential in CD-1 strain mice. The compound was given daily by gavage at 160, 1,600, and 16,000 micrograms/kg for 21 months. Necropsies were done on all animals and the incidences of non-neoplastic and neoplastic changes analyzed for significance by life table methods. The only statistically significant non-neoplastic compound-related findings were epithelial hyperplasia and hyperkeratosis of the gastric mucosa and hyperostosis of bone in the marrow cavity of sternebrae and femurs. The changes in the gastric epithelium are characteristic of some prostaglandins and were expected. The bone hyperostosis was associated with misoprostol in high dosages, and was considered unique to the mouse. Other non-neoplastic findings were typical of known spontaneous conditions in mice. The most frequent neoplasm was the hepatocellular adenoma followed by lymphosarcoma, lung alveolar carcinoma, and Harderian gland adenoma. Several proliferative lesions of the duodenum were considered to be spontaneous. These were focal avillous hyperplasia, focal atypical hyperplasia, and junctional polyp. There was no evidence that misoprostol is carcinogenic for CD-1 mice.

Prostaglandin E1-associated pathology of pulmonary microvasculature in newborn pups: similarity to findings in prostaglandin E1-treated human newborns.

Prostaglandin E1 (PGE1) administration is a useful therapeutic measure for short-term maintenance of ductal patency in patients with obstructions to pulmonary or systemic blood flow. Such treatment is not without complications, however, and a report of three infants from our institution with abnormalities of the pulmonary microvasculature after varying periods of PGE1 therapy was recently published (Heffelfinger et al., Pediatr Pathol 1987;7:165-73). The vascular abnormalities appeared to be temporally related to the PGE1 administration. To test this hypothesis, we investigated the effects of PGE1 in newborn beagles by infusing PGE1 for periods of up to 21 days in four experimental pups. Two control pups were infused with saline for the same period of time. Five of the animals developed respiratory infection during the course of the infusions. One PGE1-treated pup was not infected. Both the PGE1- and saline-treated pups had bronchopneumonias of similar severity; however, pulmonary arteritis occurred only in the PGE1-treated pups. The severity of the arteritis varied with the amount of pulmonary parenchymal inflammation and not with the duration of PGE1 administration. Inflammatory and vascular lesions were found in organs other than the lung only in two pups receiving longer courses of PGE1 treatment. We conclude that systemic PGE1 infusion at therapeutic levels plays a role in the development of arterial lesions in small muscular arteries and that this is potentiated by the presence of infection.

Developmental toxicity of alprostadil in rats after subcutaneous administration or intravenous infusion.

Timed-pregnant Upj:TUC(SD)spf (Sprague-Dawley) rats were dosed with alprostadil (prostaglandin E1), either subcutaneously on Days 6-15 of gestation at 0.0, 0.5, 1.0, or 2.0 mg/kg/day or by iv infusion into the jugular vein (24 hr/day) on Days 7-15 at 0.0, 0.5, 1.0, 2.0, 4.0, or 6.0 mg/kg/day. Maternal toxicity was observed in all dams receiving alprostadil subcutaneously, the severity of which increased in a dose-related manner. Toxicity also was evident in the offspring in the 2.0 mg/kg/day group as evidenced by a significant increase in the percentage of resorptions and a significant decrease in the percentage of live fetuses. Mean fetal weight was significantly depressed in all three alprostadil-treated groups and several skeletal and visceral variations were significantly higher in the 1.0 and 2.0 mg/kg/day groups than in the vehicle control group; in addition, there were two instances of significantly increased frequencies of skeletal variations in the 0.5 mg/kg/day group. Gross, visceral, and skeletal malformations were significantly increased in the high-dose group. During iv infusion of alprostadil more than 50% of the dams in the 6.0 mg/kg/day group died and there was one death in the 4.0 mg/kg/day group. Significant decreases in maternal weight gain between Days 7 and 11 of gestation were observed at doses of 1.0 mg/kg/day and above. However, continuous iv infusion of this prostaglandin, at dosages which were not severely toxic to the dams, was judged not to be teratogenic or otherwise embryotoxic in rats. The increase in uterine contractions, observed at 1.0 and 2.0 mg/kg after sc administration to rats implanted with chronic uterine microballoons, was consistent with the hypothesis that the developmental toxicity observed after bolus sc administration was the consequence of decreased blood flow in the uterus and/or placenta and/or embryos.

Effect of chronic misoprostol ingestion on rat gastric morphology and cell turnover.

The effect of long-term misoprostol - a synthetic prostaglandin E1 analogue - ingestion on rat gastric morphology and cell turnover was studied. Misoprostol in a daily dose of 90 micrograms/kg or 9,000 micrograms/kg was intragastrically administered to rats. Control rats were treated with the vehicle only. Following 90 days of treatment, 3H thymidine was injected i.v. and rats were sacrificed 1 h later. Tissue sections were prepared from the stomach body and subjected to autoradiography. Misoprostol treatment significantly reduced body weight gain. High dose misoprostol treatment induced significant increases in gastric wall thickness and in gastric gland length. On the other hand, the labelling index was significantly reduced by treatment with high dose misoprostol. These results indicate that chronic administration of misoprostol in high doses increases gastric wall thickness and decreases gastric cell turnover, suggesting that administration of prostanoids causes an increase in cell survival and a decrease in cell shedding.

Adverse effects of (15S)-15-methyl-prostaglandin E1 in normal and paraquat-exposed rats.

Single, daily injections of approximately 1 mg/kg of (15S)-15-methyl-PGE1 (mPGE1), a PGE1 analog, have been reported to inhibit inflammation and to prolong survival in several animal models of local and systemic inflammation. We examined the effect of this dose of mPGE1 on paraquat toxicity in rats. A significant increase in early mortality was identified in mPGE1-treated rats as early as 3 hr following injection of paraquat and appeared associated with increased respiratory effort. Rats given mPGE1 without paraquat also appeared to increase respiratory effort but did not die. Rats killed at 3 hr following injections demonstrated increased lung weights in both paraquat-injected and control animals receiving mPGE1. Although a neutrophilia was identified in these animals, no significant increase in lung lavage neutrophils or albumin was identified. These data suggest that large intermittent doses of a PGE1 analog may adversely affect the respiratory system of normal and injured animals, and will accelerate mortality following exposure to potentially lethal doses of paraquat.

Gastric protection by misoprostol against 1300 mg of aspirin. An endoscopic study.

Misoprostol, a synthetic prostaglandin E1 analog, is being evaluated in the treatment of peptic ulcer. It has been reported to have both antisecretory and cytoprotective properties. In this placebo-controlled, double-blind study, pretreatment with 200-micrograms doses of misoprostol was evaluated in the prevention of gastric injury caused by aspirin. Five oral doses of misoprostol or placebo were administered over 24 hr followed by a single oral 1296-mg dose of aspirin 30 min after the fifth dose of test agent. Two hours later the gastric mucosa was examined with a small-caliber fiberendoscope. Protection was defined as no more than 10 petechiae and no more than two hemorrhagic streaks in the gastric mucosa. Twenty of 30 (67%) subjects who received misoprostol was protected, whereas only one of 30 (3%) subjects receiving placebo was protected. The difference between the effects of misoprostol and placebo was highly significant (P less than 0.001). We concluded that five 200-micrograms doses of misoprostol given over 24 hr protects the gastric mucosa from the injurious effect of a single dose of aspirin.

Preclinical toxicology profile of misoprostol.

The toxicity of misoprostol has been extensively examined in a variety of in vitro and in vivo studies. Preclinical studies evaluated acute and chronic toxicity, mutagenicity and carcinogenicity, and reproductive toxicity. Single oral dose studies in rodents and non-rodents indicate a safety margin of at least 500 to 1000 fold between lethal doses in animals and therapeutic doses in humans. Chronic toxicity studies (52 weeks) have been performed at daily oral doses of up to 300 and 9000 micrograms/kg body weight in dogs and rats, respectively. Rectal temperatures were increased at 100 and 300 micrograms/kg in dogs and serum iron was increased at 9000 micrograms/kg in rats. Stomach weights were increased in dogs and rats in a dose-correlated manner related, at least in part, to an increase in the number of normal epithelial cells (gastric hyperplasia). When drug treatment was stopped rectal temperatures, serum iron and stomach weights reverted to normal. Electron microscope studies on hyperplastic tissue showed that the ultrastructure was not affected. Hyperostosis has been observed, mainly in female mice, following prolonged drug treatment at high doses. Histological studies of bone tissues of rats and dogs and radiological studies of long bones of dogs following chronic administration of misoprostol showed that bone development was normal in all respects. Mutagenicity studies were negative and misoprostol was not fetotoxic or teratogenic in rats at oral doses up to 10000 micrograms/kg body weight, or in rabbits at doses up to 1000 micrograms/kg body weight.(ABSTRACT TRUNCATED AT 250 WORDS)

A double-blind study of prophylactic effect of misoprostol on lesions of gastric and duodenal mucosa induced by oral administration of tolmetin in healthy subjects.

Tolmetin, a nonsteroidal antiinflammatory drug, is known to induce edema, submucosal hemorrhage, and erosions of the gastrointestinal tract when administered at recommended doses. The purpose of our study was to determine whether misoprostol prevented or reduced the severity of duodenal and gastric mucosal injury induced by tolmetin. Following endoscopic screening, 60 healthy male and female subjects were assigned at random to one of two treatment groups. One group was treated with tolmetin (2000 mg/day, in four divided doses) and misoprostol (200 micrograms four times daily); the other with tolmetin and placebo. Both drugs were administered for six and a quarter days. On the seventh day, 2 hr after the last dose, an endoscopic examination of the gastric and duodenal mucosa was repeated, and the results graded. Subjects with 10 or fewer hemorrhages or erosions were considered treatment successes; those with 11 or more erosions, plus any other lesions, were considered treatment failures. A total of 59 subjects completed the study. One withdrew because of an unsuspected pregnancy. In regard to the gastric mucosa, seven of 29 (24%) placebo subjects were considered treatment successes. In the misoprostol group, 27 of 30 (90%) were treatment successes. This difference is statistically significant at the P less than 0.0001 level. The overall damage to the duodenal mucosa caused by tolmetin is less than that to the gastric mucosa, with the misoprostol-treated subjects having significantly less damage than the placebo subjects (P less than 0.001). Side effects were common in both groups, but almost all were mild, gastrointestinal in origin, and did not require treatment or withdrawal from the study.(ABSTRACT TRUNCATED AT 250 WORDS)