Stability of misoprostol tablets collected in Malawi and Rwanda: Importance of intact primary packaging.

Misoprostol is listed in the WHO essential medicines list and can be used for induction of labour, for prevention and treatment of post-partum haemorrhage, and for abortions. The compound is unstable, and substandard misoprostol preparations have been detected in low- and middle-income countries. We now investigated the stability of misoprostol tablets according to the international guidelines for stability testing of pharmaceutical products. Three brands (four batches) of misoprostol tablets were collected in Malawi and Rwanda: the originator product, a WHO-prequalified product, and a generic product without WHO prequalification. A further batch of the originator product was collected in Germany. To investigate the effect of damage to the primary packaging, additional blister strips of one sample were intentionally damaged with a needle and investigated in parallel. Samples were placed in stability chambers for six months at 40°C/75% relative humidity (RH) and at 25°C/60% RH. After 0, 1, 2, 3 and 6 months, misoprostol content was determined according to the International Pharmacopeia. At 40°C/75% RH, all samples showed a decline of misoprostol content, but four of the batches still remained within the pharmacopeial specifications, while one of the two batches of the generic product without WHO-prequalification showed a final content of 86.2% which is out of specifications. Damage to the primary packaging greatly decreased stability, resulting in a final content of only 48.2% of the declared misoprostol amount. At 25°C/60% RH all samples remained in specifications for six months, even the sample with the damaged blister. Dissolution of misoprostol remained in specifications of the pharmacopoeia for six months for all batches, except for the sample with damaged blisters stored at 40°C/75% RH. This study confirms that the stability of misoprostol tablets must be ensured by intact, good-quality primary packaging. Careful supplier qualification is required in the procurement process.

Crystal structure of misoprostol bound to the labor inducer prostaglandin E2 receptor.

Misoprostol is a life-saving drug in many developing countries for women at risk of post-partum hemorrhaging owing to its affordability, stability, ease of administration and clinical efficacy. However, misoprostol lacks receptor and tissue selectivities, and thus its use is accompanied by a number of serious side effects. The development of pharmacological agents combining the advantages of misoprostol with improved selectivity is hindered by the absence of atomic details of misoprostol action in labor induction. Here, we present the 2.5 Å resolution crystal structure of misoprostol free-acid form bound to the myometrium labor-inducing prostaglandin E2 receptor 3 (EP3). The active state structure reveals a completely enclosed binding pocket containing a structured water molecule that coordinates misoprostol's ring structure. Modeling of selective agonists in the EP3 structure reveals rationales for selectivity. These findings will provide the basis for the next generation of uterotonic drugs that will be suitable for administration in low resource settings.

Intravaginal rings for continuous low-dose administration of cervical ripening agents.

Intravaginal rings (VRs) have been widely reported for administration of pharmaceutical drugs - most notably estrogens, progestogens and antiretrovirals - to the vagina for clinical benefit. Here, for the first time, we describe the design, manufacture and preclinical testing of VRs for sustained/controlled release of the cervical ripening agents isosorbide mononitrate (ISMN) and misoprostol (MP), either singly or in combination. Matrix-type silicone elastomer VRs containing ISMN showed declining daily release rates, ranging from 31 to 168 mg (Day 1) to 3-25 mg (Day 11). Novel orifice-type rings, in which a MP-containing silicone elastomer core is partially exposed to the external environment by overmolding with a non-medicated silicone elastomer sheath containing orifices, provided relatively constant daily MP release rates over 14 days (∼20 or 60 µg/day depending on the formulation type). Combination VRs offered simultaneous release of both ISMN and MP over 14 days, with an almost constant MP release rate (60 µg/day) and steadily declining daily ISMN release (295 mg on Day 1 and 24 mg on Day 11). The VR design can be readily tailored to provide sustained or controlled release of ISMN and MP at rates potentially useful for cervical ripening.

Development and validation of LC methods for the separation of misoprostol related substances and diastereoisomers.

Misoprostol is a synthetic prostaglandin E1 analogue which is mainly used for prevention and treatment of gastric ulcers, but also for abortion due to its labour inducing effect. Misoprostol exists as a mixture of diastereoisomers (1:1) and has several related impurities owing to its instability at higher temperatures and moisture. A simple and robust reversed phase liquid chromatographic (RPLC) method is described for the separation of the related substances and a normal phase (NP) LC method for the separation of misoprostol diastereoisomers. The RPLC method was performed using an Ascentis Express C18 (150 mm × 4.6 mm, 5 µm) column kept at 35 °C. The mobile phase was a gradient mixture of mobile phase A (ACN-H2O-MeOH, 28:69:3 v/v/v) and mobile phase B (ACN-H2O-MeOH, 47:50:3 v/v/v) eluted at a flow rate of 1.5 mL/min. UV detection was performed at 200 nm. The NPLC method was undertaken by using an XBridge bare silica (150 mm × 2.1 mm, 3.5 µm) column at 35 °C. The mobile phase contained 1-propanol-heptane-TFA (4:96:0.1%, v/v/v), pumped at a flow rate of 0.5 mL/min. UV detection was performed at 205 nm. This LC method can properly separate the two diastereoisomers (Rs > 2) within an analysis time of less than 20 min. Both methods were validated according to the ICH guidelines. Furthermore, these new LC methods have been successfully applied for purity control and diastereoisomers ratio determination of misoprostol bulk drug, tablets and dispersion.

Instability of misoprostol tablets stored outside the blister: a potential serious concern for clinical outcome in medical abortion.

INTRODUCTION: Misoprostol (Cytotec) is recognised to be effective for many gynaecological indications including termination of pregnancy, management of miscarriage and postpartum haemorrhage. Although not licensed for such indications, it has been used for these purposes by millions of women throughout the world. Misoprostol tablets are most often packaged as multiple tablets within an aluminium strip, each within an individual alveolus. When an alveolus is opened, tablets will be exposed to atmospheric conditions. OBJECTIVE: To compare the pharmaco technical characteristics (weight, friability), water content, misoprostol content and decomposition product content (type A misoprostol, type B misoprostol and 8-epi misoprostol) of misoprostol tablets Cytotec (Pfizer) exposed to air for periods of 1 hour to 720 hours (30 days), to those of identical non exposed tablets. METHODS: Four hundred and twenty (420) tablets of Cytotec (Pfizer) were removed from their alveoli blister and stored at 25°C/60% relative humidity. Water content, and misoprostol degradation products were assayed in tablets exposed from 1 to 720 hours (30 days). Comparison was made with control tablets (N=60) from the same batch stored in non-damaged blisters. Statistical analyses were carried out using Fisher's exact test for small sample sizes. RESULTS: By 48 hours, exposed tablets demonstrated increased weight (+4.5%), friability (+1 300%), and water content (+80%) compared to controls. Exposed tablets also exhibited a decrease in Cytotec active ingredient dosage (-5.1% after 48 hours) and an increase in the inactive degradation products (+25% for type B, +50% for type A and +11% for 8-epi misoprostol after 48 hours) compared to controls. CONCLUSION: Exposure of Cytotec tablets to 'typical' European levels of air and humidity results in significant time-dependent changes in physical and biological composition that could impact adversely upon clinical efficacy. Health professionals should be made aware of the degradation of misoprostol with inappropriate storage of misoprostol tablets.

Validated method for the determination of misoprostol acid in whole blood by ultra performance liquid chromatography-tandem mass spectrometry.

Misoprostol is a pharmaceutical synthetic compound, analog of prostaglandin E1, frequently used as an abortifacient in not medically supervised or self-induced abortions, particularly in countries with restrictive abortion laws representing a serious public health problem. The aim of this study was to develop and validate a sensitive analytical method for the determination of misoprostol acid in whole blood samples. The samples were prepared by SPE and the chromatographic separation was performed by UPLC-MS/MS using ESI- and MRM mode with an Acquity UPLC(®) BEH C18 (50mm×2.1mm i.d., 1.7µm) column using a methanol-ammonium 0.1% solution gradient in a total run time of 7.0min. The method showed to be selective and linear in range 25-2000ng/L. The LOD and LOQ were 10ng/L and 25ng/L, respectively. The recovery ranged from 89 to 97%. No carryover and significant matrix effect were observed. The intra- and inter-assay precisions and the inter-assay accuracy results were 4.0% and 5.4%, 5.5% and 4.1%, and -1.4% and -2.8%, for the concentrations 50 and 500ng/L, respectively. The method developed allows the analysis of misoprostol acid in whole blood samples with adequate sensitivity to the concentration range obtained from therapeutic doses. The method was successfully used in a controlled misoprostol administration study and has been applied in our laboratory in the forensic toxicology field.

[Developmental toxicity of misoprostol: an update]. / Toxicidad del misoprostol sobre la gestación: Revisión de la literatura.

Misoprostol, a synthetic analog of prostaglandin E1, is currently used in Chile and other countries as an antiulcer medication, mainly for the prevention of non-steroidal anti-inflammatory-induced gastric ulcers. Due to its uterotonic properties, it is also indicated in obstetrics for induction of labor and termination of pregnancy. In this last case, misoprostol is either used alone or in combination with other oxytocic drugs such as methotrexate or mifepristone. The use of misoprostol as an abortifacient agent is considered to be safe since it rarely causes serious side effects. However up to 15 % of misoprostol-induced-abortions may not be successful, even under medical supervision, leading to in utero exposure to the drug and to the induction of a series of birth defects including limb and joints defects and Moebius syndrome. Reports from the nineties failed to show a strong epidemiological association between in utero drug exposure and induction of defects, a situation that has changed now that the number of cases reported has increased. Since the practice of abortion is illegal in Chile, many women turn to off-medical procedures to interrupt their pregnancy and use misoprostol as an easy and cheap alternative, readily available in the INTERNET. The lack of medical supervision in these cases may lead to situations that favor the induction of congenital defects. Here, we present an updated review of scientific data, to evaluate the risk of birth defects in babies exposed to the drug during pregnancy termination failed attempts.

Development and validation of highly sensitive method for determination of misoprostol free acid in human plasma by liquid chromatography-electrospray ionization tandem mass spectrometry: application to a clinical pharmacokinetic study.

A highly sensitive, selective and evaporation free SPE extraction, ESI-LC-MS/MS method has been developed for estimation of misoprostol free acid in human plasma using misoprostol acid-d(5) as an internal standard (IS). The analyte was separated using isocratic mobile phase on reverse phase column and analyzed by MS/MS in the multiple reaction monitoring mode using the respective [M-H] anions, m/z 367-249 for misoprostol acid and m/z 372-249 for the IS. The total run time was 5.0 min and the elution of misoprostol acid and misoprostol acid-d(5) (IS) occurred at 3.6 min. The developed method was validated in human plasma with a lower limit of quantification of 2.5 pg/mL. A linear response function was established for the range of concentrations 2.5-1200 pg/mL (r>0.998) for misoprostol acid in human plasma. The intra and inter-day precision values for misoprostol acid met the acceptance as per FDA guidelines. Misoprostol acid was stable in the battery of stability studies viz., bench-top, auto-sampler and freeze/thaw cycles. The developed assay method was applied to an oral pharmacokinetic study in humans.

Toxicidad del misoprostol sobre la gestación: Revisión de la literatura / Developmental toxicity of misoprostol: An update

Misoprostol, a synthetic analog of prostaglandin E1, is currently used in Chile and other countries as an antiulcer medication, mainly for the prevention of non-steroidal anti-infammatory-induced gastric ulcers. Due to its uterotonic properties, it is also indicated in obstetrics for induction of labor and termination of pregnancy. In this last case, misoprostol is either used alone or in combination with other oxytocic drugs such as methotrexate or mifepristone. The use of misoprostol as an abortifacient agent is considered to be safe since it rarely causes serious side effects. However up to 15 percent of misoprostol-induced-abortions may not be successful, even under medical supervision, leading to in utero exposure to the drug and to the induction of a series of birth defects including limb and joints defects and Moebius syndrome. Reports from the nineties failed to show a strong epidemiological association between in utero drug exposure and induction of defects, a situation that has changed now that the number of cases reported has increased. Since the practice of abortion is illegal in Chile, many women turn to off-medical procedures to interrupt their pregnancy and use misoprostol as an easy and cheap alternative, readily available in the INTERNET. The lack of medical supervision in these cases may lead to situations that favor the induction of congenital defects. Here, we present an updated review of scientifc data, to evaluate the risk of birth defects in babies exposed to the drug during pregnancy termination failed attempts.

Misoprostol associated refractile material in fetal and placental tissues after medical termination of pregnancy.

Misoprostol is a synthetic prostaglandin analog administered vaginally to induce labor for intrauterine death or termination of pregnancy for congenital abnormalities. We encountered a case of misoprostol induction of labor at 14 weeks of gestation for fetal acrania associated with amniotic bands. Histology demonstrated abundant deposits of refractile material appearing to be of vegetable fiber origin on the maternal surface of the fetal membranes. Misoprostol tablet scrapings had a similar microscopic appearance. Ten additional placentas from cases of misoprostol induction of labor between 16 and 18 weeks of gestation were examined and half were found to contain such deposits. No deposits were seen in cases between 15 and 18 weeks of gestation where misoprostol was not used. We attribute the refractile material to a nonmedicinal ingredient, microcrystalline cellulose, in the misoprostol tablet preparation. This study demonstrates that vaginal administration of misoprostol tablets can be detected microscopically in at least half of cases and may have a florid appearance simulating a potential causative factor of fetal malformation. Despite the large amounts of microcrystalline cellulose and its apparent embedding in placental tissue, the misoprostol in our index case was unlikely to have caused the amniotic bands and the resulting cranial abnormality.

Method to determine stability and recovery of carboprost and misoprostol in infusion preparations.

The two synthetic prostaglandin analogues, carboprost and misoprostol, are used extensively in obstetric and gynaecological practice. Our recent research of these compounds' use for intra-umbilical injection to treat adherent placenta necessitated their storage in solution for 3-4 days. This raised concerns over the stability and applied dosage in the in-house infusion preparations. It requires various pharmacological preparations before administration in clinical practice. We used LCMS to develop a simultaneous, valid, fast and simple method to assess the stability and recovery of their in-house preparations in different conditions. The linearity between 0-40 microg/ml was above 0.995. The reproducibility (CV) was within 5.2%. The limit of quantitation of the method for both compounds is about 2 microg/ml. The accuracy of both compounds from 0.4-40 microg/ml is 96.4-104.3% while the precision is 0.4-7.4%. The recoveries of carboprost in the infusion were from 100.3+/-4.0 to 102.4+/-1.6% and that of misoprostol in Cytotec tablet was from 44.9+/-3.5 to 50.0+/-5.0% in water and saline at 4 degrees C and room temperature. No interference was found from the matrix and between the tested compounds. The compounds were basically stable for 6 days in water and in saline, whether they were stored at 4 degrees C or at room temperature. However, only half of the dosage of misoprostol was recovered in the solution. Therefore, misoprostol dosage should be adjusted before clinical application.

The effect of Misoprostol, a prostaglandin E1 analog, on apoptosis in ischemia-reperfusion-induced intestinal injury.

The aim of this study was to investigate whether Misoprostol, a synthetic prostaglandin (PG) E1 analog, has any effect on the prevention of apoptosis in ischemia-reperfusion (I/R)-induced intestinal injury. Thirty adult male Wistar albino rats were divided into three groups: group I=sham operated+saline; group II=I/R+saline; and group III=I/R+Misoprostol. Misoprostol (50microg/kg/d) was administered as an intragastric meal for 3 days. The terminal ileum was collected for histological and biochemical investigations. Apoptotic cells were detected by terminal deoxynucleotidyl transferase-mediated dUTP nick end-labelled (TUNEL) reaction. Immunohistochemical analysis was performed to determine the distribution of inducible nitric oxide synthase (iNOS) and endothelial NOS (eNOS). Samples were also analyzed for malondialdehyde (MDA), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px). The number of TUNEL-positive cells was higher in group II when compared to the other two groups (p<0.05). In group III this value was higher when compared to group I, but lower than group II (p<0.05). iNOS immunoreactivity was not detected in ileum sections of group I animals, but moderate immunoreactivity was seen in group II and mild immunoreactivity in group III. The immunoreactivity of eNOS was moderate in ileum sections of all three groups. In ileum tissue, MDA was found to be higher in group II compared to group I (p<0.05), but there was no difference in group III. SOD was not different between groups I and III, but was significantly higher in group II (p<0.05). In our experimental model of I/R-induced intestinal injury, apoptosis is induced in enterocytes, whereas Misoprostol decreases enterocyte apoptosis in this experimental model. Our results indicate that Misoprostol may play a key role in the pathophysiologic events leading to failure of the intrinsic gut barrier defense mechanisms of intestinal epithelium.

The pharmacokinetics and different regimens of misoprostol in early first-trimester medical abortion.

Misoprostol is a synthetic prostaglandin E(1) analogue that is commonly used for medical abortion. It can be given orally, vaginally and sublingually. A pharmacokinetic study has shown that sublingual misoprostol has the shortest onset of action, the highest peak concentration and the greatest bioavailability among the three routes of administration. Earlier clinical trials have shown that vaginal misoprostol is superior to oral misoprostol when combined with mifepristone for early first-trimester medical abortion. Recent studies on the clinical efficacy of sublingual misoprostol have demonstrated that it is as effective as vaginal misoprostol. Further studies are required to determine the optimal dose and route of administration of misoprostol that can give the highest complete abortion rate, lowest ongoing pregnancy rate and least side effects.

Pharmacokinetics of prostaglandins.

Naturally occurring prostaglandins (PGs) are rapidly metabolized in the human circulation. For clinical use a number of PG analogues have therefore been developed which are resistant to rapid inactivation. Among these are carboprost, gemeprost and misoprostol. Following intramuscular injection of carboprost, plasma levels peaked after 20 minutes and declined slowly thereafter. In amniotic fluid the half-life was between 31 and 37 hours. Gemeprost is administered vaginally, and maximum plasma levels were reached after 2-3 hours, with detectable levels for at least 6-8 hours. Pharmacokinetic data on misoprostol are available following oral, vaginal and sublingual administration. Following oral treatment, plasma levels peaked at about 30 minutes, while after vaginal administration of the tablets the levels increased gradually and reached maximum levels after 70-80 minutes, but remained detectable for a significantly longer time. After sublingual administration the peak concentration was the same as for oral treatment but declined significantly more slowly. Endocervical administration of PGE(2) might be regarded as a local therapy, while following vaginal administration increased plasma levels of metabolites can generally be found. The plasma profile varies with the vehicle used.

Stabilization and sustained-release effect of misoprostol with methacrylate copolymer.

The use of ammonio methacrylate copolymer (Eudrgit RS, RL) to form a sustained-release solid dispersion of Misoprostol can improve and enhance two important physical and chemical properties of Misoprostol. First, the solid dispersion matrix formed by the copolymer can protect Misoprostol from being degraded by water so that its stability is improved. Second, Misoprostol can be slowly released by diffusion from the copolymer matrix. Accelerated stability studies of Misoprostol-Eudragit solid dispersion after storing at various temperatures for different time periods were carried out. According to high performance liquid chromatography (HPLC) analyses, the stability of Misoprostol in a series of Eudragit appeared significantly improved at different ratios. The Misoprostol-Eudragit dispersion can be used in a powder form, filled in capsules, or compressed into tablets. The dissolution profiles of Misoprostol-Eudragit solid dispersion and its tablets in water, pH 1. 2, 4.5 and 6.8, dissolution media show that this stable solid dispersion is a sustained-release type.

Effect of salicylic acid on the plasma protein binding and pharmacokinetics of misoprostol acid.

The in vitro serum protein binding and erythrocyte uptake of [3H]misoprostol acid ([3H]MPA; SC-30695), an active metabolite of the prostaglandin E1 (PGE1) analogue misoprostol, was determined in the blood of young (20-40 years) and elderly subjects (64 years or older) at concentrations ranging between 20 and 5000 pg/mL. The effect of selected other drugs on the displacement of [3H] MPA from the binding sites was also investigated. [3H]MPA serum binding (between 81 and 89 %) was similar and concentration independent in the young and elderly subjects and the erythrocyte partitioning coefficient was about 1, indicating the absence of a significant accumulation of MPA in red blood cells. Both the plasma and serum protein binding of [3H] MPA were substantially reduced in the presence of high (> 100 microg/mL) concentrations of salicylic acid. In an in vivo study, the single-dose pharmacokinetics of MPA did not change significantly when misoprostol (200 microg) was given alone or concomitantly with 975 mg of aspirin. These findings indicate that MPA is displaced from its protein binding sites only by high concentrations of salicylic acid and that this displacement is unlikely to be of clinical significance with the usual therapeutic doses of aspirin.

Misoprostol dehydration kinetics in aqueous solution in the presence of hydroxypropyl methylcellulose.

Misoprostol (Searle), and E1-type prostaglandin, is known to be stabilized in the form of a solid dispersion with hydroxypropyl methylcellulose (HPMC), yet no evidence has been found for specific intermolecular interactions. In the present study, the dehydration kinetics of this prostaglandin were studied in aqueous solution in the absence and the presence of HPMC. The dispersion of the drug with HPMC, when dissolved in pH 7.66 aqueous solution, exerted a small but significant stabilizing effect. A possible interpretation of this kinetic result, together with lack of evidence for complex formation in both the solid and solution states, may be that HPMC exerts its stabilizing effect by physically limiting the access of water the prostaglandin through an entanglement of the prostaglandin in the polymer environment, the diffusion of drug away from the polymer being slow on the time scale of the dehydration kinetics.

Mechanism of misoprostol stabilization in hydroxypropyl methylcellulose.

The stability of misoprostol oil is significantly improved in a hydroxypropyl methylcellulose (HPMC) dispersion (1:100). In order to understand the enhanced stability of misoprostol oil in HPMC, the physical state of misoprostol oil in HPMC films was investigated using differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and transmission IR (TIR). Further, to determine the effect of polymer structure and the mobility of both water and misoprostol on misoprostol stability, the rate of misoprostol degradation was investigated in the misoprostol/HPMC dispersion (1:100) at 55 degrees C. The water sorption isotherm of the dispersion at 55 degrees C was determined, at seven different relative humidities, ranging from zero to 81%. The DSC and DMA measurements indicated that misoprostol oil, up to 29% in dry weight, is molecularly dispersed in the glassy HPMC. The TIR studies showed no evidence of complexation between misoprostol and HPMC. Stability studies of the misoprostol/HPMC (1:100) dispersion indicated that the first-order rate constants for misoprostol degradation increased in a concave-up fashion as the water content of the dispersion increased. Below two percent water content, the rate of misoprostol degradation was found to be minimal. Overall, it is suggested that misoprostol is stabilized in the dispersion by being molecularly dispersed in HPMC. Further, the glassy state of HPMC should reduce the mobility of misoprostol and water, leading to a minimal rate of degradation for misoprostol at low moisture levels.