Misoprostol is a synthetic prostaglandin medication used to prevent and treat stomach and duodenal ulcers, induce labor, cause an abortion, and treat postpartum bleeding due to poor contraction of the uterus. Misoprostol is taken by mouth when used to prevent gastric ulcers in persons taking NSAIDs. For abortions, it is used by itself and with mifepristone or methotrexate. By itself, the effectiveness for abortion is between 66% and 90%. For labor induction or abortion, it is taken by mouth, dissolved in the mouth, or placed in the vagina. For postpartum bleeding, it may also be used rectally.
Some studies suggest that inducing an abortion using misoprostol alone is no less safe than the combined method. Misoprostol reduces the need for suction dilation and curettage (D&C) by up to 60% and shortens the time to complete abortion compared with placebo. The World Health Organization recommends misoprostol as a safe alternative when mifepristone isn’t available.
How is misoprostol used?
For abortion and labor induction, vaginal administration of misoprostol is recommended for increased efficacy. The recommended dose of misoprostol is 800 mcgs (4 200-mcg tablets) inserted vaginally. Study results have demonstrated that vaginal administration is more effective than oral use of misoprostol. One dose is about 70% effective, and two are about 84% effective.
The recommended adult oral dose of misoprostol for reducing the risk of NSAID-induced gastric ulcers is 200 mcg four times daily with food. If this dose cannot be tolerated, a dose of 100 mcg can be used. Misoprostol should be taken for the duration of NSAID therapy as prescribed by the physician. Misoprostol should be taken with a meal, and the last dose of the day should be at bedtime.
However, studies have shown that the administration of misoprostol by the sublingual route is better than the oral and vaginal routes for cervical ripening.
The sublingual misoprostol tablets are to be placed between the cheek and gum. These automatically dissolve, and particles that remain can be swallowed with a glass of water.
How long does it take for sublingual misoprostol to dissolve?
Sublingual misoprostol dissolves within 15–20 minutes. It is convenient to administer and avoids the discomfort associated with vaginal administration. Sublingual misoprostol is taken by mouth but it can avoid the first-pass effect through the liver as in the oral route and therefore, may result in a higher complete abortion rate. Studies reveal that sublingual misoprostol of 600 mcg or vaginal misoprostol of 800 mcg as the first dose is effective in producing complete abortion within about 24 hours.
How long does it take for misoprostol to dissolve vaginally?
When inserted vaginally, it takes about 30 minutes for misoprostol tablets to dissolve. Vaginal administration results in serum concentrations that increase gradually, reaching a maximum level after 70–80 min. Misoprostol causes cramping and bleeding to empty your uterus. For most people, the cramping and bleeding usually start 1-4 hours after taking the misoprostol.
If bleeding does not occur within 48 hours, then a repeat misoprostol dose should be administered. Bleeding is usually heavier than menses and is generally accompanied by severe cramping. It is normal to see the passage of blood clots and tissue. Heavy bleeding and cramping usually last for about 4 hours. Patients should be relaxing during this time and not engaging in strenuous activity.
How long does it take for misoprostol to work orally?
Following 400 µg oral misoprostol administration, Serum misoprostol level increases rapidly and peaks at about 30 minutes.