Misoprostol: new frontiers; benefits beyond the gastrointestinal tract

Lack of evidence for neonatal misoprostol neurodevelopmental toxicity in C57BL6/J mice

Misoprostol is a synthetic analogue of prostaglandin E1 that is administered to women at high doses to induce uterine contractions for early pregnancy termination and at low doses to aid in cervical priming during labor. Because of the known teratogenic effects of misoprostol when given during gestation and its effects on axonal growth in vitro, we examined misoprostol for its potential as a neurodevelopmental toxicant when administered to neonatal C57BL6/J mice. Mice were injected subcutaneously (s.c.) with 0.4, 4 or 40 µg/kg misoprostol on postnatal day 7, the approximate developmental stage in mice of human birth, after which neonatal somatic growth, and sensory and motor system development were assessed. These doses were selected to span the range of human exposure used to induce labor. In addition, adult mice underwent a battery of behavioral tests relevant to neurodevelopmental disorders such as autism including tests for anxiety, stereotyped behaviors, social communication and interactions, and learning and memory. No significant effects of exposure were found for any measure of development or behavioral endpoints. In conclusion, the results of the present study in C57BL/6J mice do not provide support for neurodevelopmental toxicity after misoprostol administration approximating human doses and timed to coincide with the developmental stage of human birth.

In vitro effects of non-steroidal anti-inflammatory drugs on cytokine, prostanoid and matrix metalloproteinase production by interface membranes from loose hip or knee endoprostheses

OBJECTIVE

To study the effects of the non-steroidal anti-inflammatory drugs (NSAIDs) aceclofenac, piroxicam, tenoxicam and indomethacin on cytokine, matrix metalloproteinases (MMPs), tissue inhibitors of metalloproteinases (TIMPs) and prostaglandin E2 (PGE2) production, by interface membranes (IFT), obtained at revision surgery for aseptic loosening of total joint arthroplasty. Involvement of these soluble factors is well documented and probably, a pharmaceutically induced inhibition of them might retard loosening.

METHODS

IFTs from 10 patients with a loose hip or knee endoprosthesis were collected. The possibility of septic loosening was thoroughly excluded by histopathologic and microbiologic evaluation. IFTs were cultured in the absence or presence of the tested drugs and the levels of the soluble mediators were determined, using electrophoretic and enzyme-linked immunosorbent assay techniques. Paracetamol was used as neutral drug.

RESULTS

All NSAIDs exhibited a pronounced inhibitory effect upon the production of interleukin-6 (IL-6) and tumour necrosis factor-alpha (TNF-alpha). This specific effect on IL-6 is reported in the literature for the first time. The majority of NSAIDs also induced the production of IL-1beta in an adequate portion of samples. These drugs did not have a clear effect on MMP synthesis, but they had a stimulatory tendency on TIMP-1 production. Paracetamol, significantly decreased the synthesis of TNF-alpha and that of the gelatinases.

CONCLUSION

Our in vitro results are encouraging, since it appears that the action of NSAIDs, globally considered, may be beneficial upon the loosening process. The inhibitory effect of paracetamol upon TNF-alpha and gelatinases is intriguing. Our data, if supported by similar observations, probably justify performance of long-term clinical trials.

Misoprostol therapeutics revisited

Misoprostol, a prostaglandin E1 analog, is a racemate of four stereoisomers. On administration it rapidly de-esterifies to its active form, misoprostolic acid. Misoprostolic acid is 85% albumin bound and has a half-life of approximately 30 minutes. It is excreted in urine as inactive metabolites. No significant drug interactions have been reported. Besides its gastrointestinal protective and uterotonic activities, misoprostol regulates various immunologic cascades. It inhibits platelet-activating factor and leukocyte adherence, and modulates adhesion molecule expression. It protects against gut irradiation injury, experimental gastric cancer, enteropathy, and constipation. It improves nutrient absorption in cystic fibrosis. Misoprostol has utility in acetaminophen and ethanol hepatotoxicity, hepatitis, and fibrosis. It is effective in asthmatics and aspirin-sensitive asthmatic and allergic patients. It lowers cholesterol and severity of peripheral vascular diseases, prolongs survival of cardiac and kidney transplantation, synergizes cyclosporine, and protects against cyclosporine-induced renal damage. It works against drug-induced renal damage, interstitial cystitis, lupus nephritis, and hepatorenal syndrome. It is useful in periodontal disease and dental repair. Misoprostol enhances glycosoaminoglycan synthesis in cartilage after injury. It prevents ultraviolet-induced cataracts and reduces intraocular pressure in glaucoma and ocular hypertension. It synergizes antiinflammatory and analgesic effects of diclofenac or colchicine and has been administered to treat trigeminal neuralgic pain. It reduces chemotherapy-induced hair loss and recovery time from burn injury, and is effective in treating sepsis, multiple sclerosis, and pancreatitis.

Effect of misoprostol on the secretion of histamine from basophils of whole blood

BACKGROUND

Misoprostol (MSP), the synthetic prostaglandin E1 (PGE1) analog, possesses multifunctional features, including modulating some inflammatory aspects of immune and allergic disorders.

OBJECTIVES

To investigate the effect of MSP on histamine release (HR) from basophils of whole blood using anti-IgE, specific allergens, and calcium ionophore.

METHODS

The study was performed using the automated glass fiber-based whole blood leukocyte histamine release test (LHRT).

RESULTS

Very low concentrations of MSP produced a marked inhibition of HR induced with anti-IgE. Maximum inhibition was observed at 10-9 M. It was also shown that the levels of HR inhibition with MSP varied at different incubation times. The greatest inhibition of HR was noted at 1 to 2 hours of incubation at MSP concentrations of 10-8 and 10-9 M, respectively. Incubation of blood from allergic patients at the optimal MSP concentration and optimal elapsed time (2 hours) resulted in significant reductions of allergen-specific HR induced by both Timothy pollen grass allergen and D.pteronissinus. Incubation of blood with varying concentrations of MSP and subsequent stimulation with calcium ionophore A23187 also inhibited HR from basophils. In the latter case, the most effective concentrations of MSP ranged from 10-8 to 10-6 M.

CONCLUSIONS

This study demonstrated that MSP can inhibit basophil HR indicating a potentially beneficial role of PGE1 analogs as pharmacotherapy for allergic diseases.

Effects of misoprostol and prostaglandin E2 on proteoglycan biosynthesis and loss in unloaded and loaded articular cartilage explants

The effects of misoprostol, a prostaglandin E1 analog, and prostaglandin E2 on proteoglycan biosynthesis and loss were studied in unloaded and mechanically loaded mature bovine articular cartilage explants. The prostaglandins were administered daily at dosages of 0, 10, 100 and 1000 eta g/ml for up to seven days, and proteoglycan biosynthesis determined by measurement of radiolabelled sulfate incorporation. The presence of misoprostol lead to a significant (p < 0.001) dose-dependent inhibition (30%-50%) in proteoglycan biosynthesis which was also dependent on exposure time (p < 0.05). A significant decrease in biosynthesis (34%) was also found for prostaglandin E2, but only at the highest dose (1000 eta g/ml). Proteoglycan catabolism rates were not affected by either substance as assessed by loss of newly synthesized proteoglycan. The application of a continuous cyclic mechanical compressive load (stress of 1.0 MPa at 1 hertz for 24 hours) resulted in a significant inhibition of proteoglycan biosynthesis (up to 50%) as compared to unloaded explants. However, there was no additive effect when mechanical load and misoprostol or prostaglandin E2 were combined. These results suggest that prostaglandins may have a role in the degenerative and repair process in various forms of arthritis where elevated intra-articular levels of prostaglandin E2 are present.

The effects of chronic administration of indomethacin and misoprostol on renal function in cirrhotic patients with and without ascites

BACKGROUND

Non-steroidal anti-inflammatory drugs (NSAIDs) often cause renal dysfunction in cirrhotic patients with ascites through inhibition of prostaglandin synthesis. However, their renal effects in cirrhotic patients without ascites are controversial. In addition, the role of prostaglandins in cirrhotic patients with ascites and in non-ascitic cirrhotic patients receiving NSAIDs also remains elusive. Thus we evaluated the chronic renal effects of indomethacin and misoprostol in 9 cirrhotic patients with ascites (protocol 1) and 21 cirrhotic patients without ascites (protocol 2).

METHODS

The patients of protocol 1 received 200 micrograms of misoprostol every 6 h for 7 consecutive days. In protocol 2, 11 patients received 25 mg indomethacin three times a day for 7 consecutive days. The other 10 patients received 25 mg indomethacin three times a day plus 200 micrograms misoprostol every 6 h for 7 consecutive days. Renal function tests, plasma renin activity, and plasma aldosterone concentration were measured before and after treatment.

RESULTS

In protocol 1, misoprostol tended to reduce the urinary sodium excretion (p = 0.08). In protocol 2, indomethacin alone greatly impaired renal plasma flow (p < 0.05), creatinine clearance (p < 0.05), blood urea nitrogen (p < 0.05), and serum creatinine (p = 0.06) in 11 patients. Similar magnitudes of renal dysfunction were observed in the other 10 patients despite the concomitant misoprostol treatment.

CONCLUSION

Chronic administration of misoprostol may have caused a negative natriuretic effect in cirrhotic patients with ascites. In cirrhotic patients without ascites chronic administration of indomethacin may induce a renal dysfunction that cannot be reversed by misoprostol.

Experience with misoprostol therapy for NSAID gastropathy in children

OBJECTIVE

To determine the effect of misoprostol, a synthetic prostaglandin E1 analogue, on the gastrointestinal tract (GIT) symptoms associated with non-steroidal anti-inflammatory drug (NSAID) administration and on the haemoglobin value, in children.

METHODS

Retrospective chart review of children attending the paediatric rheumatology clinic at a tertiary referral hospital over a three year period, who were receiving NSAIDs and were prescribed misoprostol for treatment of GIT symptoms or anaemia.

RESULTS

Twenty five children (mean age 12.0 (SD 2.8) (range 7-17) years were prescribed misoprostol (mean dose 308.4 (76.5) micrograms/m2/day; 9.8 (2.5) micrograms/kg/day) while NSAID therapy was continued. Of the 22 (88%) patients with GIT complaints, 18 (82%) had complete resolution of symptoms and two (9%) had some improvement. Four patients (18%) had a recurrence of symptoms after initial resolution while still receiving misoprostol. Misoprostol therapy was associated with a statistically significant increase in haemoglobin concentration (mean value before misoprostol 115 (18) g/l; after misoprostol 126 (15) g/l (p = 0.02)). The only adverse effect reported was self limited diarrhoea in one child.

CONCLUSION

Misoprostol appeared to be effective in the treatment of GIT symptoms in children receiving NSAIDs and to result in significant increase in the haemoglobin concentration. Further prospective studies are needed to evaluate the role of misoprostol therapy for NSAID associated GIT complaints in the paediatric population.

Modulation of IL-4 production in murine spleen cells by prostaglandins

Recently, it has been reported that IL-4 production by murine Th2 cell lines is insensitive to inhibition by E-type prostaglandins. In the present study, IL-4 production in vitro by freshly isolated concanavalin A (Con A)-stimulated murine spleen cells was readily suppressed by PGE2 with an I50 of 2 nM. Comparable suppression by PGE2 was seen after priming by anti-CD3 epsilon antibody instead of Con A or with other changes in the culture conditions. PGE2 was an effective inhibitor after elimination of Ly2.2+ T cells, consistent with a direct effect on Th2 cells. In the absence of added prostaglandins, IL-4 production was enhanced 1.5- to 7.0-fold by 0.2-2.0 microM indomethacin, indicating that endogenous arachidonate metabolites such as PGE2 and PGI2 regulate IL-4 production in our usual culture system. The inhibition of Th2 cell secretion by PGE2 in vitro may have physiologic and pharmacologic implications for the regulation of Th2 cell function and IgE production in vivo.

Dose-dependent effects of oral misoprostol on renal function in alcoholic cirrhosis

BACKGROUND/AIMS

Prostaglandins are important modulators of renal physiology, particularly when the effective circulatory volume is decreased. The aim of this study was to determine the dose-dependent effects of an oral prostaglandin E1 analogue, misoprostol, on renal function in patients with well-compensated alcoholic cirrhosis.

METHODS

Renal hemodynamics and tubular function were assessed by clearance techniques, before and after 100-microgram, 200-microgram, 400-microgram, or 800-microgram oral doses of misoprostol.

RESULTS

Overall, the results indicate that low-dose misoprostol is vasodilatory, natriuretic, and diuretic whereas high-dose misoprostol increases renal vascular tone and inhibits sodium and water excretion. The 200-microgram dose produced a transient but significant increase in the glomerular filtration rate and effective renal plasma flow and a decrease in renal vascular resistance. Urinary volume and urinary sodium excretion increased and urinary osmolality decreased.

CONCLUSIONS

The results suggest that, in patients with well-compensated cirrhosis, the renal effects of misoprostol are determined by a bell-shaped dose-response curve. The renal vasodilatory, natriuretic, and diuretic potential of 200-micrograms of misoprostol suggests that it may be of therapeutic value in patients with cirrhosis.