misoprostol

Action and Spectrum

Actions and spectrum: 

Misoprostol stimulates contractions in the uterus by causing labor or expulsion of conception products. It has cytoprotective effects on the gastric mucosa and inhibits acid secretion by increasing mucus production making it to prevent and treat gastric ulcers induced by NSAIDs. Misoprostol is also used for gynaecological indications like cervical ripening before labor medical termination of pregnancy and postpartum hemorrhage treatment off-label. 

Drug Interaction

Adverse Reaction

Adverse Reaction  

Frequency defined 

>10% 

• Abdominal pain (13-20%) 
• Diarrhea (14-40%) 

1-10% 

• Headache (2%) 
• Frequency not defined 
• Anemia 
• Chest pain 
• Gastrointestinal hemorrhage 
• Myocardial infarction 
• Rupture of uterus 
• Anaphylaxis 
• Cardiac dysrhythmia 
• Flatulence 
• Hearing loss 
• Nausea 
• Thromboembolic disorder 

Black Box Warning

Black Box Warning: 

The warning of misoprostol for pregnant women as it can cause abortion, premature birth, or birth defects. It should not be used to reduce NSAID-induced ulcers in childbearing women unless the patient is at high risk of complications from gastric ulcers and NSAID use and low risk of complications from surgical abortion. 

Contraindication / Caution

Contraindication/Caution: 

Contraindications include hypersensitivity to misoprostol, pregnancy, women without effective contraception, women with a history of caesarean delivery or major uterine surgery, and patients with inflammatory bowel disease as it may increase the risk of abortion and uterine rupture. 

Misoprostol treats uterine irregularities but it should be used with caution by women with an IUD in place and those with a hx of cesarean delivery, uterine surgery, previous uterine rupture, anemia, hypotension, dehydration, breastfeeding, allergy to prostaglandins, inflammatory bowel disease (IBD), pregnant women to reduce the risk of NSAID-induced ulcers, and patients receiving magnesium-containing antacids to avoid increased diarrhea risks. It is essential to consult a healthcare professional before using misoprostol. 

Comorbidities: 

Misoprostol can cause fluid retention that potentially causing heart failure exacerbation in patients with a history of cardiovascular disease. In renal impairment patients it can lead to potential toxicity. Hepatic impairment may result in reduced drug clearance necessitating dose adjustments. It can also cause bronchoconstriction, exacerbate asthma, and cause uterine contractions that potentially leading to abortion or premature labor in childbearing women. Effective contraception is recommended and pregnancy should be ruled out before treatment. Patients with these conditions should be closely monitored and monitored while taking misoprostol. 

Pregnancy / Lactation

Pregnancy consideration:  

Pregnancy category: X 

Lactation: misoprostol is not recommended during lactation. 

Pregnancy category: 

• Category A: Satisfactory and well-controlled studies show no risk to the fetus in the first or later trimester. 
• Category B: There is no evidence of risk to the fetus found in animal reproduction studies and there are not enough studies on pregnant women. 
• Category C: Adverse effects on the fetus found with evidence in animal reproduction studies and no adequate evidence for an effect in humans, care must be taken for potential risks in pregnant women. 
• Category D: There is adequate data available with sufficient evidence of human fetal risk from various platforms, but despite potential risks may be used only in emergency cases for potential benefits. 
• Category X: Drugs listed in this category outweigh risks over benefits These category drugs should be prohibited for pregnant women. 
• Category N: There is no data available for the drug under this category. 

Pharmacology

Pharmacology: 

Misoprostol is a synthetic prostaglandin E1 analog with antisecretory and cytoprotective properties. It works by binding to the prostaglandin E receptor in gastric parietal cells by inhibiting gastric acid secretion and increasing mucus and bicarbonate production to protect the gastrointestinal mucosa. Misoprostol also causes uterine contractions and cervical ripening by binding to the prostaglandin E receptors in the myometrium and cervix. 

 Pharmacodynamics: 

Misoprostol binds to smooth muscle cell EP receptors and increase contractions by causing uterine contractions, cervical dilation, and decreased gastric acid secretion.  

It is used to induce labor, ripen the cervix, terminate pregnancy and manage postpartum hemorrhage thus prevent and treat NSAID-induced stomach ulcers, and induce abortion.  

Misoprostol stimulates mucus production and bicarbonate secretion in the stomach by preventing and treating NSAID-induced gastric ulcers. 

Pharmacokinetics: 

Absorption 

It is absorbed rapidly after oral administration with peak plasma concentrations occurring within 30 to 60 minutes.  

The oral bioavailability of 80-85% can also be administered vaginally for cervical ripening and labor induction. 

Distribution 

It is highly protein-bound to plasma proteins and distributed throughout the body including the uterus and gastrointestinal tract and is highly distributed. 

Metabolism 

It is primarily metabolized in the liver through oxidation and hydrolysis forming various active metabolites but most is excreted unchanged in feces. 

Elimination and excretion 

It is primarily eliminated in the feces, half-life is 20 to 40 minutes. 

Adminstartion

Administration: 

Misoprostol prevents gastric ulcers in patients taking NSAIDs. It can be administered via oral, sublingual, buccal, vaginal, or rectal routes.  

Patient Information Leaflet

Patient information leaflet 

Generic Name: misoprostol 

Pronounced: [ mye-so-prah-stole] 

Why do we use misoprostol? 

Misoprostol used to prevent stomach ulcers caused by NSAIDs, prepare the cervix for labor induction and speed up labor. It is used in medical abortion with mifepristone to prevent or treat postpartum hemorrhage. It may also be used before certain procedures to soften and open the cervix like dilation and curettage or hysteroscopy.