Evaluating misoprostol content in pregnant women with hourly oral administration during labor induction by microElution solid phase extraction combined with liquid chromatography tandem mass spectrometry.

Misoprostol is a widely used alternative of prostaglandin for labor induction. Based on previous studies, we envision that small and frequent oral dosage of misoprostol is an effective method for labor induction. To monitor the misoprostol content during labor induction, a rapid, sensitive, and selective microElution solid phase extraction (µElution SPE) combined with liquid chromatography tandem mass spectrometry (LC-MS/MS) was developed. Using µElution SPE could minimize the sample consumption and elution volume in order to maximize the sample enrichment and throughput. The misoprostol acid, a metabolite of misoprostol, was gradient separated in a Bidentate C18 column, then quantified by highly-selective reaction monitoring (H-SRM) in a total run time of 6min. The developed method was optimized and validated in human plasma, and showed linear range of 0.01-10ng/mL. The limit of detection (LOD) was 0.001ng/mL. The recovery ranged from 89.0 to 96.0%, and no significant matrix effect or carryover was observed. The precision, accuracy and stability were met with the criteria of U.S. FDA guidance. The developed method was successfully applied to evaluate misoprostol concentration during labor induction in pregnant women. The concentration-time profiles approves that hourly oral administration of misoprostol is a safe and effective method without drug accumulation for labor induction.

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.

Effect of bacterial vaginosis on the pharmacokinetics of misoprostol in early pregnancy.

BACKGROUND: Misoprostol has been shown to be an effective agent for cervical ripening and termination of early pregnancy especially when administered vaginally. Our objective was to evaluate whether bacterial vaginosis (BV) affected the pharmacokinetics of vaginally administered misoprostol during early pregnancy. METHODS: Ten women with BV and 10 healthy women requesting medical abortion up to 9 weeks of pregnancy were administered 200 mg mifepristone followed 24-48 h later by a single dose of 800 µg misoprostol vaginally. Blood samples were taken before (0 h) and 0.5, 1, 2, 3 and 4 h after misoprostol administration. Misoprostol acid was determined in serum samples using liquid chromatography/tandem mass spectrometry. RESULTS: All women with BV had a vaginal pH > 4.7. The mean bioavailability measured as the area under the curve (AUC) and maximum concentration (C(max)) appeared higher in the control than in the BV group (1458.7 versus 878.1 pg h/ml) and (630.7 versus 342.5 pg/ml), respectively, but did not achieve statistical significance and there was no other significant difference in the pharmacokinetics between the two groups. However, if two women with vaginal pH > 4.7 were excluded from the control group the difference in AUC240 (1359 versus 878.1 pgh/ml) reached statistical significance (P = 0.048). CONCLUSIONS: BV had an effect on pharmacokinetics of vaginally administered misoprostol in early pregnancy. However, the results should be interpreted with caution due to the small sample size and marked individual variations.

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.

Pharmacokinetics of repeated doses of misoprostol.

BACKGROUND: Misoprostol is widely used in obstetrics and gynaecology for medical abortion, cervical priming and induction of labour. To aid the design of effective and safe regimens, we have investigated the pharmacokinetic parameters after the vaginal or sublingual administration of repeated doses of 400 microg of misoprostol. METHODS: Women undergoing termination of pregnancy by suction evacuation were randomized to receive 400 microg of sublingual or vaginal misoprostol every 3 h for five doses. Venous blood was taken at 180, 200, 240, 360, 380, 420, 540, 560, 600, 720, 740, 780 and 900 min after the first dose of misoprostol for determination of the plasma level of misoprostol acid (MPA). RESULTS: The peak plasma levels of MPA decreased with successive doses of vaginal misoprostol, whereas the peak plasma levels were similar with successive doses of sublingual misoprostol. After the third dose, the peak plasma levels of MPA after sublingual misoprostol were significantly higher than those after vaginal administration. After the final dose, the area under the MPA concentration-time curve after sublingual administration was significantly higher than that after vaginal misoprostol (P < 0.031). However, subgroup analysis in the vaginal administration group showed that the progressive decline in the peak plasma levels of MPA occurred only in women with significant vaginal bleeding. CONCLUSIONS: The peak plasma level of MPA after each dose of misoprostol is higher and the bioavailability is also greater after sublingual administration, compared with that after vaginal administration, of repeated doses of misoprostol. The difference was probably due to the reduction in absorption of vaginal misoprostol in the presence of significant vaginal bleeding.

Pharmacokinetic profiles up to 12 h after administration of vaginal, sublingual and slow-release oral misoprostol.

BACKGROUND: It has been shown that the route of administration of misoprostol has a strong impact on the pharmacokinetic profile and result in different clinical efficacy. No study has so far evaluated the pharmacokinetics beyond 6 hours. Furthermore a new slow-release misoprostol formulation was included in the study. METHODS: Pharmacokinetics of a novel slow-release (SR) oral misoprostol was compared during 12 h after administration to conventional misoprostol administered vaginally or sublingually. Thirty-three women requesting surgical abortion up to 12 weeks were randomly allocated to groups receiving a single dose of 400 microg conventional misoprostol administered vaginally or sublingually or 800 microg SR oral misoprostol. Blood samples were taken before (0 h) and 0.5, 1, 2, 3, 4, 6, 8, 10 and 12 h after misoprostol administration. Misoprostol acid (MPA) was determined in serum samples using liquid chromatography/tandem mass spectrometry. RESULTS: Three women did not complete the study. Serum concentrations reached their highest level following sublingual misoprostol (P<0.0001) and the time to peak concentration was shortest for this group (P=0.0094). The area under the curve (AUC) up to 12 h was greater following sublingual treatment than for the other alternatives (P<0.0001) and lowest for SR misoprostol. Cumulative serum levels of MPA did not increase beyond 6 h following sublingual and vaginal administration, while they continued to increase up to 12 h following SR misoprostol. CONCLUSIONS: The new SR form of misoprostol demonstrated lower peak levels and a lower AUC but longer lasting elevation in serum levels when compared to conventional misoprostol administered sublingually or vaginally. SR misoprostol may offer an alternative to repeated administration of conventional misoprostol.

Determination of misoprostol acid in human plasma by liquid chromatography coupled to tandem mass spectrometry.

A rapid and sensitive liquid chromatographic/tandem mass spectrometric method for determination of misoprostol acid, the active metabolite of misoprostol, was developed and validated. Following liquid-liquid extraction, the analytes were separated using an isocratic mobile phase on a C(18) column. An API 4000 tandem mass spectrometer equipped with Turbo IonSpray ionization source was used as detector and was operated in the negative ion mode. Multiple reaction monitoring using the precursor to product ion combinations of m/z 367-249 and 296-269 was performed to quantify misoprostol acid and the internal standard hydrochlorothiazide, respectively. The method was linear in the concentration range of 10.0-3000 pg mL(-1) using 200 microL plasma. The lower limit of quantification was 10.0 pg mL(-1). The intra- and inter-day relative standard deviation over the entire concentration range was less than 8.3%. Accuracy determined at three concentrations (25.0, 200 and 2700 pg mL(-1) for misoprostol acid) ranged from -0.5 to 1.2% in terms of relative error. Each plasma sample was chromatographed within 3.5 min. The method was successfully used in a pharmacokinetic study of misoprostol in human plasma after an oral administration of 0.6 mg misoprostol.

Pharmacokinetics of a controlled-release misoprostol vaginal insert at term.

OBJECTIVE: The objective of this investigation was to report the pharmacokinetic properties of misoprostol administered intravaginally to women at term via a controlled-release hydrogel polymer insert. METHODS: This open-label, dose escalation trial consisted of 31 nulliparous women at term who were treated intravaginally in cohorts of six with inserts containing reservoirs from 25 through 300 microg (7 at 200 microg) of misoprostol. Inserts remained intravaginally until the patient went into labor, developed adverse events, or completed 24 hours of treatment. Complete data about residual drug in the inserts and plasma concentrations of misoprostol acid were gathered for 27 and 25 patients, respectively. RESULTS: Misoprostol was released at a constant rate (5.1% total dose per hour) with the amount absorbed being directly proportional to the dose reservoir. For the 25-, 50-, 100-, 200-, and 300-microg reservoir doses, the maximum median plasma concentrations were 6.4, 11.3, 21.7, 40.8, and 74.2 pg/mL, respectively, and the area under the curve until drug removal was 39, 117, 223, 269, and 477 pg x h/mL. Regardless of dose, the peak plasma concentration occurred at approximately 7 hours after insertion and the elimination half-life of the misoprostol acid was 0.55 hours (95% confidence interval, 0.36 to 1.32 hours). CONCLUSIONS: Misoprostol is released from the vaginal insert in a controlled manner and is eliminated rapidly after removal. Pharmacokinetic parameters are proportional to the reservoir dose.

Comparison of misoprostol plasma concentrations following buccal and sublingual administration.

BACKGROUND: New indications for misoprostol include medical abortion, cervical softening, induction of labor and treatment of postpartum hemorrhage. Various routes of misoprostol administration under study include oral, vaginal, buccal, sublingual and rectal. MATERIALS AND METHODS: This was an open-label, randomized, cross-over study of the pharmacokinetic differences of buccal vs. sublingual misoprostol 800 mug in 10 healthy women. RESULTS: Of the 10 women enrolled, 2 withdrew after experiencing excessive cramping from the sublingual route of misoprostol. The mean misoprostol plasma concentration-time curves at 4 h [area under the curve (AUC)0-4)] and the maximum concentration (C(max)) showed that levels were significantly higher for sublingual administration than the buccal route. Buccal misoprostol administration resulted in fewer symptoms and was found to be more acceptable. CONCLUSIONS: Sublingual administration of misoprostol had a higher AUC and C(max) compared with buccal administration. The pharmacokinetics may help to determine the best application of misoprostol depending on the indication.

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.

The pharmacokinetics of the prostaglandin E1 analogue misoprostol in plasma and colostrum after postpartum oral administration.

OBJECTIVE: To study pharmacokinetics of prostaglandin E1 analogue, misoprostol in plasma and colostrum after postpartum oral administration. STUDY DESIGN: Twenty women received 600 microg doses of misoprostol orally after delivery. Plasma levels of the principal metabolite, misoprostol acid, were measured at 2, 10, 20, 30, 40, 50, 60, 90, 120, 180, 240 and 300 min (48 samples). Colostrum was expressed from the breasts to measure misoprostol acid at 60, 120, 180, 240, and 300 min (24 samples). Assay was done using isotope dilution gas chromatography (GC)/negative ion chemical ionisation mass spectrometry (MS). RESULTS: The plasma concentration of misoprostol acid rose quickly. Two minutes after oral administration its mean level was 91.5 pg/ml, peaked at 20 min (344 pg/ml), then fell steeply by 120 min (27.8 pg/ml) and remained low for the duration of the study. Misoprostol acid in colostrum reached maximum concentration of 20.9 pg/m within 1h after oral administration. It then declined gradually to 17.8 pg/ml at 2h, 2.8 pg/ml at 4h and to <1 pg/ml at 5h. Areas under misoprostol concentration versus time curves up to 5h were 290.1 pgh/ml in the plasma and 51.4 pgh/ml in colostrum, respectively. CONCLUSION: Misoprostol acid is secreted in colostrum within 1h of oral administration of 600 microg of misoprostol; the pharmacokinetics of misoprostol after oral administration during postpartum is similar to that of other pregnancy periods.

Oral misoprostol is rapidly absorbed in postpartum women at term.

OBJECTIVE: To determine the rate of bioavailability of oral misoprostol in the tablet and a new capsule form in women with term pregnancies in the postpartum period. METHODS: Twenty-seven women received 400 microg of misoprostol orally after delivery of the fetal vertex in either the standard tablet form or crushed in methylcellulose capsules prepared in our pharmacy. Serum levels of misoprostol free acid, the principal metabolite, were measured at 5-, 15- and 30-min intervals after administration of the medication. The pharmacokinetics of the tablet and capsule groups were then compared. RESULTS: Twenty patients were included in the analysis. At 5 min, there was a trend towards a statistically significant difference in the concentration of misoprostol acid in the tablet group (89 pg/ml) versus the capsule group (20 pg/ml) (p = 0.007). No significant difference in plasma concentration was noted in the two groups at 15 min (tablet group, 256 pg/ml; capsule group, 245 pg/ml; p = 0.85) or 30 min (tablet group, 381 pg/ml; capsule group, 455 pg/ml; p = 0.45). CONCLUSION: Oral misoprostol is rapidly absorbed and bioavailable in the postpartum period. Misoprostol may prove useful in postpartum management. The novel packaging of misoprostol in capsule form allows for double-blinded studies with similar pharmacokinetics to the standard tablet.

Determination of misoprostol free acid in human breast milk and serum by gas chromatography/negative ion chemical ionization tandem mass spectrometry.

To study an expected transition of misoprostol from human blood into breast milk, a novel method for the determination of its active metabolite misoprostol acid (MPA) was developed. MPA was determined in serum and breast milk samples by an isotope dilution assay using gas chromatography/negative ion chemical ionization tandem mass spectrometry (GC/NICI-MS/MS). After addition of (15S)-15-methylprostaglandin E(2) (15-methyl-PGE(2)) as an internal standard, MPA was extracted from both matrices using a reversed-phase cartridge. The prostanoids were derivatized with O-2,3,4,5,6-pentafluorobenzylhydroxylamine hydrochloride (PFBHA) and 2,3,4,5,6-pentafluorobenzyl bromide (PFBB) to the pentafluorobenzyl oxime (PFBO)-pentafluorobenzyl ester (PFB) derivatives. The sample was subjected to thin-layer chromatography with ethyl acetate-hexane (1 : 1 (v/v)) as the developing solvent. The corresponding zone was extracted. After derivatization to the trimethylsilyl ether, MPA was determined by GC/NICI-MS/MS using the [molecule (M) - pentafluorobenzyl (PFB)](-) ([P](-)) ions as precursor in the negative ion chemical ionization mode. The product ions used for quantification were [P - 2TMSOH - C(6)F(5)CH(2)OH](-) (MPA) and [P - 2TMSOH - C(6)F(5)CH(2)OH - CO(2)](-)(15-methyl-PGE(2)), respectively. The limit of quantification for MPA was approximately 1 pg ml(-1) in breast milk and serum samples. The correlation coefficients of the calibration curves for MPA were r > 0.997 in the 0.5-2000 pg ml(-1) range for both tested matrices.

Effect of misoprostol (PGE1) on glucose metabolism in type-2-diabetic and control subjects.

In vitro and in vivo studies have demonstrated that prostaglandins of the E series enhance muscle glucose uptake. We examined the effect of acute misoprostol (PGE1) administration on whole body insulin-mediated glucose disposal, as well as the major intracellular pathways of glucose metabolism in type 2 diabetic (n = 10) and non-diabetic (n = 4) subjects. Each subject received two 240-min euglycaemic insulin (40 mU/m2/min) clamp studies with tritiated glucose and indirect calorimetry. During one of the insulin clamp studies, 200 microg of misoprostol was ingested at 90 and 150 min after the start of the insulin infusion. Insulin-mediated total body glucose disposal, glycolysis, glycogenesis and glucose oxidation were similar during the insulin clamp studies performed without and with misoprostol in both the diabetic and non-diabetic groups. These results demonstrate that the acute administration of misoprostol does not enhance insulin-mediated glucose disposal in either type-2-diabetic or non-diabetic subjects.

Pharmacokinetics of different routes of administration of misoprostol.

BACKGROUND: The pharmacokinetic parameters of four different routes of administration of a single dose of 400 microg of misoprostol were studied. METHODS: A total of 40 women undergoing termination of pregnancy by suction evacuation was randomized by computer model to receive 400 microg of misoprostol by one of four routes: (i) sublingual (ii) oral (iii) vaginal and (iv) vaginal with addition of water. Venous blood samples were taken at 0, 1, 2, 5, 10, 20, 30, 45, 60, 120, 240 and 360 min after the administration of misoprostol. Misoprostol acid (MPA) was determined in serum samples using gas chromatography/tandem mass spectrometry. RESULTS: Sublingual misoprostol achieved the highest serum peak concentration (Cmax) (574.8 +/- 250.7 pg/ml) of MPA and this was significantly higher than those in the other groups [Oral: 287.6 +/- 144.3 pg/ml (P < 0.01), vaginal: 125.2 +/- 53.8 pg/ml (P < 0.001) and vaginal with water: 162.8 +/- 57.1 pg/ml (P < 0.001)]. The time to peak concentration (Tmax) was similar in both the sublingual (26.0 +/- 11.5 min) and oral groups (27.5 +/- 14.8 min) and was significantly shorter than those in both vaginal groups. The area under the MPA concentration versus time curve up to 360 min in the sublingual group (743.7 +/- 291.2 pg.h/ml) was significantly greater than those in oral (402.8 +/- 151.6 pg.h/ml, P < 0.05) and vaginal (433.7 +/- 182.6 pg.h/ml, P < 0.05) groups, but no significant difference was found between sublingual and vaginal administration if water (649.3 +/- 333.8 pg.h/ml) was added. CONCLUSION: The new sublingual route of administration of misoprostol demonstrated a great potential to be developed into a method of medical abortion.

A high performance liquid radiochromatographic assay for the simultaneous analysis of iloprost and misoprostol.

A high-performance liquid chromatographic (HPLC) method utilizing ultraviolet absorbance coupled with radioisotove detection was developed for the precise and simultaneous determination of iloprost and misoprostol. This assay allows complete resolution of iloprost diastereoisomers and has a total run time of approximately twenty minutes. Samples were prepared for chromatographic analysis by extracting a mixture of tritiated drugs from rat plasma with acetonitrile. The resulting solutions were chromatographed on a reversed phase Zorbax Rx-C8 column using 0.02M potassium phosphate (pH 3.0), acetonitrile, and methanol (46:30:24, v/v) at a flow rate of 1.7 mL/min. 2-Naphthoic acid was employed as an internal standard. The correlation coefficient for varying concentrations of tritiated iloprost (12.7 Ci/mmol specific activity) from 2.18 ng/mL to 21.8 ng/mL was 0.995, and the correlation coefficient for concentrations of tritiated misoprostol (50 Ci/mmol specific activity) from 0.617 ng/mL to 6.17 ng/mL was 0.993. The high selectivity and sensitivity of this assay make it useful for the simultaneous quantitation of iloprost and misoprostol.

Pharmacokinetics of diclofenac and misoprostol when administered alone or as a combination product.

The pharmacokinetics of a new diclofenac/misoprostol combination dosage form have been investigated. Diclofenac is a nonsteroidal anti-inflammatory drug (NSAID) that has been commercially available for many years and its pharmacokinetics are well documented. Similarly, misoprostol is a prostaglandin analogue with well documented pharmacokinetics. It is available commercially as both an effective treatment for peptic ulceration and as prophylaxis of NSAID-induced gastric and duodenal damage. The aim of studies of the diclofenac/misoprostol combination dosage form has been to determine the potential for drug-drug interactions between the 2 drugs when they are coadministered. A single dose crossover study in young healthy volunteers showed no statistically significant differences between the plasma concentrations of either diclofenac or misoprostol when the drugs were each administered alone and those after administration of the combination dosage form. Although not statistically significant, slight variations in plasma diclofenac concentrations appeared to occur between dosage forms. Use of a replicate design study in which the same dosage of diclofenac was administered in 2 different treatment periods to elderly volunteers showed that this variation was due to interindividual variations in the disposition of diclofenac. The latter study had both single and multiple dose components and confirmed the lack of interaction between misoprostol and diclofenac at steady-state. Thus, diclofenac and misoprostol may be given in a combination dosage form without either drug altering the pharmacokinetics of the other.

Biopharmaceutical profile of diclofenac-misoprostol combination tablet, Arthrotec.

Arthrotec, a combination tablet has been developed that contains 50 mg of diclofenac in an inner core and 200 micrograms of misoprostol in an outer mantle. Both diclofenac and misoprostol are extensively absorbed and their maximum plasma concentrations, but not total availability, are diminished when taken with food. Both drugs have elimination half-lives of less than 2 hours and do not accumulate in plasma after recommended doses. Pharmacokinetic and bioavailability studies of the combination product taken separately and together reveal a high between- and within-subject variability in plasma diclofenac levels, especially when the enteric-coated tablets were given after food; reliable values for peak plasma diclofenac concentration could not be ascertained. No pharmacokinetic interactions between diclofenac and misoprostol were apparent. The bioavailability of diclofenac and misoprostol from the combination tablet was similar to that seen when the two drugs are given separately.