Misoprostol is an agonist of prostaglandin E2 (PGE2) receptors, binding to EP2, EP3, and EP4 subtypes with reported binding constants (Kc) of 34 nM, 7.9 nM, and 23 nM, respectively.[1]

Misoprostol, a PGE2 receptor agonist that is utilized clinically as an anti-ulcer agent and signals through the protective PGE2 EP2, EP3, and EP4 receptors, would reduce brain injury in the murine middle cerebral artery occlusion–reperfusion (MCAO-RP) model. Administration of misoprostol, at the time of MCAO or 2 h after MCAO, resulted in significant rescue of infarct volume at 24 and 72 h. Immunocytochemistry demonstrated dynamic regulation of the EP2 and EP4 receptors during reperfusion in neurons and endothelial cells of cerebral cortex and striatum, with limited expression of EP3 receptor. EP3−/− mice had no significant changes in infarct volume compared to control littermates. Moreover, administration of misoprostol to EP3+/+ and EP3−/− mice showed similar levels of infarct rescue, indicating that misoprostol protection was not mediated through the EP3 receptor. Taken together, these findings suggest a novel function for misoprostol as a protective agent in cerebral ischemia acting via the PGE2 EP2 and/or EP4 receptors.

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In primary neuronal cultures and organotypic hippocampal slices treated with either NMDA (10 μM) or subjected to oxygen-glucose deprivation (OGD), Misoprostol at concentrations ranging from 10 nM to 10 μM did not elicit any protective response.[1]

In a murine middle cerebral artery occlusion-reperfusion (MCAO-RP) model, subcutaneous administration of Misoprostol (1 mg/kg) at the onset of 90-minute MCAO, followed by subsequent injections at 6 and 12 hours of reperfusion, resulted in a significant reduction in infarct volume in cerebral cortex, striatum, and hemisphere at 24 hours post-ischemia. Neurological scores were also significantly improved in the Misoprostol-treated group.[1]
When administered 2 hours after MCAO onset, with subsequent doses at 8 and 14 hours, Misoprostol again resulted in a significant reduction in infarct volume in cerebral cortex, striatum, and hemisphere, along with improved neurological scores at 24 hours.[1]
When administered 2 hours after MCAO, with subsequent doses at 6 and 12 hours, and brains examined at 72 hours, Misoprostol provided comparable protection, significantly reducing infarct volume and improving neurological scores at this delayed time point.[1]
Laser Doppler flowmetry measurements indicated no differences in cerebral blood flow between vehicle and Misoprostol-treated groups during ischemia and reperfusion.[1]
Studies using EP3 receptor knockout (EP3-/-) mice showed that genetic deletion of the EP3 receptor did not affect infarct volume in the MCAO-RP model. Furthermore, administration of Misoprostol to EP3-/- mice resulted in a similar level of infarct reduction as in wild-type (EP3+/+) mice, indicating that the neuroprotective effect of Misoprostol is not mediated through the EP3 receptor.[1]
Immunohistochemical analysis revealed dynamic regulation of EP2 and EP4 receptor expression during reperfusion. Neuronal expression decreased in the ischemic core, while endothelial expression was markedly induced in the peri-infarct area at 4 hours. By 24 hours, EP2 (but not EP4) expression persisted in endothelium. This suggests endothelial cells and/or neurons in the peri-infarct zone as potential cellular targets for Misoprostol.[1]

Immunocytochemistry (Immunostaining) was performed to investigate receptor expression. Brain tissue from sham and MCAO-RP mice was harvested at specified time points. Sections were likely processed for antigen retrieval, blocked, and incubated with primary antibodies against EP2, EP3, EP4 receptors, and cell-specific markers (e.g., NeuN for neurons, Factor VIII or ICAM-1 for endothelial cells, GFAP for astrocytes, Iba1 for microglia). After washing, sections were incubated with appropriate fluorescently-labeled secondary antibodies. Colocalization was assessed using microscopy to determine receptor expression in specific cell types during reperfusion.[1]
For the assessment of neuroprotection in vitro, primary neuronal cultures and organotypic hippocampal slices were used. These cultures/slices were treated with the excitotoxic agent NMDA (10 μM) or subjected to oxygen-glucose deprivation (OGD) to induce injury. Misoprostol was applied at concentrations ranging from 10 nM to 10 μM. Neuronal survival or injury was assessed, but no protective effect was observed under these conditions.[1]

Subcutaneous injection of misoprostol resulted in significant reductions in infarct size when given at the time of MCAO and 2 h after the onset of MCAO, with comparable protection at 24 and 72 h after MCAO.[1]

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For the middle cerebral artery occlusion-reperfusion (MCAO-RP) model, male mice (10-12 weeks old, 20-25 g) were used. Focal cerebral ischemia was induced by 90 minutes of reversible right MCA occlusion under isoflurane anesthesia, followed by 22.5 or 72 hours of reperfusion.[1]
Misoprostol was formulated in hydroxypropyl-methyl cellulose (HPMC) vehicle. Mice received subcutaneous injections of either the vehicle or Misoprostol at a dose of 1 mg/kg.[1]
Three different dosing regimens were used: 1) First dose at the onset of MCAO, followed by subsequent doses at 6 and 12 hours of reperfusion. 2) First dose 2 hours after MCAO onset, followed by subsequent doses at 8 and 14 hours. 3) First dose 2 hours after MCAO onset, followed by subsequent doses at 6 and 12 hours, with termination at 72 hours.[1]
Infarct volume was assessed at 24 or 72 hours after MCAO using triphenyltetrazolium chloride (TTC) staining or histopathology. Neurological deficits were scored at 22.5 hours. Physiological parameters (e.g., rectal temperature) and cerebral blood flow (via laser Doppler flowmetry) were monitored in separate cohorts.[1]
For studies involving EP3 receptor knockout mice, male 12-week-old EP3-/- and EP3+/+ littermates were subjected to MCAO-RP with or without Misoprostol treatment, following similar protocols.[1]

Absorption, Distribution and Excretion
Following oral administration of 800 µg misoprostol, the AUC was 2.0192 ± 0.8032 hg/mL, Cmax was 2.6830 ± 1.2161 ng/mL, and tmax was 0.345 ± 0.186 h. Following sublingual administration of 800 µg misoprostol, the AUC was 3.2094 ± 1.0417 hg/mL, Cmax was 2.4391 ± 1.1567 ng/mL, and tmax was 0.712 ± 0.415 h. Following oral administration of 800 µg misoprostol, the AUC was 2.0726 ± 0.3578 hg/mL, Cmax was 1.3611 ± 0.3436 ng/mL, and tmax was 1.308 ± 0.624 h. Up to 73.2 ± 4.6% of the radiolabeled oral misoprostol dose is recovered in the urine. Data on the volume of distribution of misoprostol are scarce. The apparent volume of distribution of the active metabolite of misoprostol is 13.6 ± 8.0 L/kg in subjects with normal renal function, 17.3 ± 23.0 L/kg in subjects with mild renal impairment, 14.3 ± 6.8 L/kg in subjects with moderate renal impairment, and 11.0 ± 9.6 L/kg in subjects with end-stage renal disease. Because misoprostol is rapidly deesterified before or during absorption, it is usually undetectable in plasma. The systemic clearance of the active metabolite of misoprostol, misoprostolic acid, is 0.286 L/kg/min. The total clearance was 0.226 ± 0.073 L/kg/min in subjects with mild renal impairment, 0.270 ± 0.103 L/kg/min in subjects with moderate renal impairment, and 0.105 ± 0.052 L/kg/min in subjects with end-stage renal disease. It is rapidly absorbed after oral administration. Elimination: Kidneys (64% to 73% of the oral dose is excreted within 24 hours). Feces (15% of the oral dose). Metabolites/Metabolites: Misoprostol is deesterified to the active metabolite misoprostol acid, also known as SC-30695. This metabolite is further reduced to dinor and tetranor metabolites (SC-41411), prostaglandin F1 (PGF1) analogues of SC-41411, and ω-16-carboxylic acid derivatives. However, most of these metabolites are underdescribed in the literature.
It is rapidly deesterified to misoprostol acid (the major bioactive metabolite). The deesterified metabolite is further metabolized via β- and ω-oxidation, a process that can occur in various tissues throughout the body.
Biological Half-Life
The half-life of an oral dose of 800 µg is 1.0401 ± 0.5090 hours, the half-life of a sublingual dose is 0.8542 ± 0.1170 hours, and the half-life of a buccal dose is 0.8365 ± 0.1346 hours.
Terminal Phase - 20-40 minutes

Interactions
Concomitant use of magnesium-containing antacids and misoprostol may exacerbate misoprostol-induced diarrhea. This study aimed to investigate the effects of acetaminophen on hepatic microvessels using vascular casting technology. Fasting male Long Evans rats were intraperitoneally injected with 650 mg/kg body weight of acetaminophen. Microvascular casting was performed at different time points after administration. Liver castings from control rats showed good patency and normal hepatic microvessels. Thirty-six hours after acetaminophen overdose, liver castings showed circular centrilobular cavities of varying sizes, lacking the filled sinusoids of the casting, while the microvessels around the portal vein were relatively normal. Signs of microvascular damage were observed as early as 5 hours after acetaminophen overdose. This damage manifested as changes in the centrilobular sinuses, including incompletely filled areas and centrilobular sinus dilatation. Treatment with misoprostol (6 x 25 μg/kg) before and after acetaminophen administration significantly reduced microvascular damage, with only small, focal areas of unfilled areas observed in casts, and the overall microvascular system remaining intact. In summary, this study demonstrates that acetaminophen overdose leads to widespread and characteristic hepatic microvascular damage in the centrilobular region. The results also suggest that microvascular damage is an early event in the pathogenesis of acetaminophen-induced hepatotoxicity. Misoprostol can protect the liver from microvascular damage. Cyclosporine A significantly improved graft survival in transplant patients, but its side effects, such as nephrotoxicity and hypertension, pose challenges to the treatment of transplant recipients. This toxicity is thought to be related to prostaglandin inhibition. Concomitant administration of misoprostol prevented chronic cyclosporine A-induced nephrotoxicity in rats, but did not prevent hypertension. This study investigated the effect of misoprostol on indomethacin-induced renal function decline. The study included 6 female patients with normal blood pressure and 6 with hypertension (mean age 60.5 years). Patients received the following treatments: 25 mg indomethacin every 6 hours for 3 days; 200 mcg misoprostol every 6 hours for 3 days; and a combination of both for 3 days. A 4-day washout period was provided between the two treatment regimens. All patients followed a low-sodium diet, and hypertensive patients received hydrochlorothiazide concurrently. Three hypertensive patients and three normotensive patients experienced a decrease in glomerular filtration rate (GFR) during indomethacin treatment. When misoprostol was used in combination with indomethacin, four of these six patients did not experience a decrease in GFR. The conclusion is that misoprostol can improve indomethacin-induced renal dysfunction in middle-aged women with normal serum creatinine undergoing low-sodium diets and diuretics. In a double-blind, placebo-controlled, randomized prospective study of 32 healthy male subjects, misoprostol was administered concurrently with acetylsalicylic acid. Fecal blood loss was measured for 8 consecutive days… Aspirin (650 mg, four times daily) and misoprostol (25 μg, four times daily) or placebo were administered on days 3, 4, and 5. The median blood loss was significantly increased in the aspirin plus placebo group (n=16) (P < 0.05), increasing from 0.81 ml/day to 6.05 ml/day. The median blood loss was slightly increased in the aspirin plus misoprostol group (n=16) (from 0.75 ml/day to 3.75 ml/day), but significantly lower than in the placebo group. The mean serum salicylate concentrations were similar in the placebo and misoprostol groups (7.8 μg/mL and 6.8 μg/mL, respectively). No significant changes were observed in laboratory values in any of the subjects, and no serious side effects were reported. This study demonstrates that even when misoprostol is administered concurrently at doses below its threshold for significantly inhibiting gastric acid secretion, oral misoprostol can still reduce aspirin-induced gastrointestinal bleeding. This suggests that misoprostol may play a role in preventing gastric mucosal damage in certain patients.

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Non-human toxicity values
Oral LD50 in rats: 81-100 mg/kg
Oral LD50 in mice: 27-138 mg/kg
Intraperitoneal LD50 in rats: 40-62 mg/kg
Intraperitoneal LD50 in mice: 70-160 mg/kg

[1]. Neurosci Lett . 2008 Jun 20;438(2):210-5.

Misoprostol may cause developmental toxicity depending on state or federal labeling requirements. Methyl 7-[(1R,2R,3R)-3-hydroxy-2-(4-hydroxy-4-methyloct-1-enyl)-5-oxocyclopentyl]heptanoate is a prostaglandin analogue. Misoprostol is a prostaglandin analogue used to reduce the risk of NSAID-associated ulcers, treat miscarriage, prevent postpartum hemorrhage, and for early pregnancy termination. Stimulation of prostaglandin receptors in the stomach reduces gastric acid secretion, while stimulation of these receptors in the uterus and cervix increases the strength and frequency of uterine contractions and reduces cervical tone. Misoprostol was approved by the U.S. Food and Drug Administration (FDA) on December 27, 1988. Misoprostol is a prostaglandin E1 analogue. It is a synthetic analogue of natural prostaglandin E1. It dose-dependently inhibits the secretion of gastric acid and pepsin and enhances the resistance of the mucosa to damage. It is an effective anti-ulcer drug and also has an oxytocin effect.
See also: Diclofenac sodium; Misoprostol (one of the ingredients).
Drug Indications

Misoprostol tablets are indicated for reducing the risk of nonsteroidal anti-inflammatory drug (NSAID)-induced gastric ulcers in high-risk patients, but not for duodenal ulcers. Misoprostol can also be used in combination with diclofenac to treat symptoms in patients with osteoarthritis or rheumatoid arthritis, especially those at high risk of gastric ulcers. Misoprostol is commonly used to treat miscarriage and prevent postpartum hemorrhage. In other countries, misoprostol can also be used alone or in combination with mifepristone for early termination of pregnancy.
FDA Label
Induction of Labor
Induction of Labor
Mechanism of Action

Misoprostol is a synthetic prostaglandin E1 analog that stimulates prostaglandin E1 receptors on gastric parietal cells, thereby reducing gastric acid secretion. Simultaneously, mucus and bicarbonate secretion increase, and the mucosal double layer thickens, enabling the mucosa to generate new cells. Misoprostol binds to endometrial smooth muscle cells, enhancing the strength and frequency of uterine contractions and degrading collagen, thus reducing cervical tension. Misoprostol enhances the natural defense mechanisms of the gastric mucosa and promotes the healing of acid-related diseases, possibly by increasing gastric mucus production and bicarbonate secretion. Misoprostol inhibits basal and nocturnal gastric acid secretion by acting directly on parietal cells; it also inhibits gastric acid secretion stimulated by food, histamine, and pentagastrin. It reduces basal pepsin secretion but has no effect on histamine stimulation. Misoprostol has no significant effect on fasting or postprandial gastrin or intrinsic factor secretion.

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Therapeutic Uses
Nonsteroidal abortifacient; anti-ulcer drug; oxytocin
Misoprostol is indicated for the prevention of gastric ulcers caused by the use of nonsteroidal anti-inflammatory drugs (NSAIDs, including aspirin), especially in patients at high risk of gastric ulcer complications, such as the elderly, and patients with other diseases or a history of gastric ulcers. /Included on US product label/
Misoprostol is also indicated for the short-term treatment of duodenal ulcers. /Not included on US product label/
The efficacy and tolerability of mifepristone in combination with misoprostol for the termination of early pregnancy (amenorrhea not exceeding 49 days) have been demonstrated.
For more complete data on the therapeutic uses of misoprostol (of 8 types), please visit the HSDB record page.

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Drug Warnings
Misoprostol is contraindicated during pregnancy. Human studies have shown that misoprostol can cause an increase in the frequency and intensity of uterine contractions. Use of misoprostol has also been associated with an increased incidence of uterine bleeding and expulsion of uterine contents. Misoprostol-induced miscarriage is likely to be incomplete, leading to very serious complications, sometimes requiring hospitalization and surgery, and may result in infertility. Misoprostol can be used by women of childbearing age who require nonsteroidal anti-inflammatory drug (NSAID) treatment and are at high risk of developing gastric ulcers due to NSAID use, or who are already at risk of developing gastric ulcers. These patients must use effective contraception, must have a negative serum pregnancy test within 2 weeks prior to starting treatment, and must begin taking misoprostol on the second or third day of their next normal menstrual cycle. Misoprostol is rapidly metabolized in the body and is therefore unlikely to be excreted into breast milk. However, it is currently unclear whether its active metabolite, misoprostolic acid, is excreted into breast milk. Therefore, misoprostol is not recommended for breastfeeding women, as misoprostolic acid may be distributed to the infant, causing severe diarrhea. Misoprostol is generally well tolerated. Age in adult patients does not appear to affect the frequency of adverse reactions. The most common adverse reactions to misoprostol treatment involve the gastrointestinal tract (e.g., diarrhea, nausea, abdominal pain). For more complete data on misoprostol (8 of 8), please visit the HSDB record page. Pharmacodynamics: Misoprostol is a prostaglandin E1 analog that reduces the risk of gastric ulcers caused by nonsteroidal anti-inflammatory drugs (NSAIDs) by decreasing gastric acid secretion from parietal cells. Misoprostol is also used to treat miscarriage, either alone or in combination with mifepristone for early termination of pregnancy. Oral misoprostol has an onset of action of 8 minutes and a duration of action of approximately 2 hours; sublingual misoprostol has an onset of action of 11 minutes and a duration of action of approximately 3 hours; vaginal misoprostol has an onset of action of 20 minutes and a duration of action of approximately 4 hours; and rectal misoprostol has an onset of action of 100 minutes and a duration of action of approximately 4 hours.

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Misoprostol is a commonly used anti-ulcer drug that works by supplementing the levels of PGE2, a cytoprotective agent in the gastric mucosa. [1]
This study found a novel potential application of misoprostol in cerebral ischemia (stroke) as a neuroprotective agent. [1]
In the MCAO-RP model, the neuroprotective effect of misoprostol was mediated by PGE2 EP2 and/or EP4 receptors, rather than EP3 receptors. [1]
Protective effects were observed even when misoprostol was administered 2 hours after stroke onset, which is a therapeutically significant time window. [1]
This study suggests that misoprostol may have potential for stroke treatment, especially considering its clinical approval and good tolerability. [1]

C22H38O5

382.54

382.271

C, 69.07; H, 10.01; O, 20.91

59122-46-2

59122-46-2

5282381

Light yellow oil
Viscous liquid

1.1±0.1 g/cm3

497.3±45.0 °C at 760 mmHg

261-263°C

160.4±22.2 °C

0.0±2.9 mmHg at 25°C

1.525

2.91

2

5

14

27

487

3

O[C@H](C1)[C@@H]([C@H](C1=O)CCCCCCC(OC)=O)/C=C/CC(C)(O)CCCC

OJLOPKGSLYJEMD-URPKTTJQSA-N

InChI=1S/C22H38O5/c1-4-5-14-22(2,26)15-10-12-18-17(19(23)16-20(18)24)11-8-6-7-9-13-21(25)27-3/h10,12,17-18,20,24,26H,4-9,11,13-16H2,1-3H3/b12-10+/t17-,18-,20-,22?/m1/s1

methyl 7-[(1R,2R,3R)-3-hydroxy-2-[(E)-4-hydroxy-4-methyloct-1-enyl]-5-oxocyclopentyl]heptanoate

SC29333; SC 29333; Misoprostol; Cytotec; Misoprostolum; Isprelor; Misopess; SC-29333; SC-30249; SC 30249; SC30249

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

DMSO: ~76 mg/mL (~198.7 mM)
Water: ~35 mg/mL
Ethanol: ~10 mg/mL

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.

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Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)
*Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution.
Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)
Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil)
Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals).

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Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)]
*Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.
Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline)
Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline)
Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline
Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil)
Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)

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Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium)
Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose
Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals).

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Oral Formulation 3: Dissolved in PEG400
Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose
Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose
Oral Formulation 6: Mixing with food powders

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Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.

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 (Please use freshly prepared in vivo formulations for optimal results.)