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An '''antispasmodic''' is a medicine that relieves smooth-muscle spasm, principally of the gastrointestinal tract and the genitourinary tract, by mechanisms that include muscarinic-receptor antagonism, blockade of smooth-muscle voltage-gated calcium channels, and direct (receptor-independent) action on smooth-muscle contractile machinery. The category is used most often for the visceral colic of irritable bowel syndrome, of biliary colic, of renal colic, of menstrual cramping, and of selected motility disorders.

The pharmacological history of the antispasmodics is dominated by the nightshade alkaloids (atropine, scopolamine, hyoscyamine) and their synthetic derivatives, described in detail under [[:Category:Antimuscarinics|antimuscarinics]]. The natural alkaloids block M3 muscarinic receptors of intestinal, biliary, urinary-tract, and uterine smooth muscle, reducing the cholinergic-mediated contraction; they have been used in clinical practice for over a century. The synthesis of quaternary-amine derivatives that do not cross the blood-brain barrier ([[wikipedia:Propantheline|propantheline]] in the 1950s, [[wikipedia:Glycopyrrolate|glycopyrrolate]] in the 1960s) reduced the central-anticholinergic toxidrome of the naturally occurring tertiary amines without reducing the peripheral antispasmodic effect.

The non-anticholinergic antispasmodics are mostly European or non-U.S. medicines. [[wikipedia:Mebeverine|Mebeverine]] (Janssen/Solvay 1965, available in the UK and continental Europe but not in the United States), [[wikipedia:Otilonium bromide|otilonium]] (1970s, Italy and Latin America), [[wikipedia:Pinaverium bromide|pinaverium]] (1970s, France and Latin America), and [[wikipedia:Trimebutine|trimebutine]] (1968, France and Canada) act by smooth-muscle-selective L-type calcium channel blockade or by mu/kappa opioid-receptor modulation on the enteric nervous system. They produce visceral antispasmodic effect with minimal systemic anticholinergic effect and are widely used in European IBS and post-cholecystectomy practice. The phloroglucinol derivative phloroglucinol (Spasfon, French use since 1965) is a direct-acting smooth-muscle relaxant used widely in France and Belgium for visceral colic and uterine cramping.

The plant-derived antispasmodics include [[wikipedia:Peppermint oil|peppermint oil]] (enteric-coated capsules; described under [[:Category:IBS_treatments|IBS treatments]]) and [[wikipedia:Iberogast|Iberogast]] (a multi-herb extract widely prescribed in Germany for functional dyspepsia and IBS, with several controlled trials suggesting benefit and a small but real hepatotoxicity signal in the case literature). The natural alkaloid [[wikipedia:Papaverine|papaverine]] (from the opium poppy, isolated by Merck in 1848, with no opioid-receptor activity despite its source) is a direct smooth-muscle relaxant used intraoperatively for vascular and ureteral spasm and intracorporeally for erectile dysfunction. The benzyl-isoquinoline derivative drotaverine (No-Spa, 1961, Hungary) is similar; it is widely used in Eastern Europe, the Middle East, and India for biliary and renal colic but is not marketed in the United States or Western Europe.

The intravenous and intramuscular antispasmodics are used for acute renal and biliary colic. Hyoscine butylbromide (Buscopan, Boehringer 1951, available globally as a parenteral and oral preparation outside the United States) is the standard parenteral antispasmodic for renal and biliary colic in much of the world; it does not cross the blood-brain barrier in clinically meaningful concentrations and so has a favourable central-toxicity profile compared to atropine. Intravenous magnesium sulfate has antispasmodic effect in selected obstetric and urinary-tract indications. Nitroglycerin (sublingual or intravenous) relaxes biliary and oesophageal smooth muscle and is used selectively in oesophageal spasm and in sphincter-of-Oddi dysfunction.

For uterine smooth-muscle spasm in dysmenorrhea, the [[:Category:NSAIDs|non-steroidal anti-inflammatory medicines]] (ibuprofen, naproxen, mefenamic acid) are first-line: they block the prostaglandin-mediated uterine contraction at its upstream signal. The hormonal contraceptives are second-line and act by suppressing ovulation and reducing endometrial proliferation. The progestin levonorgestrel-releasing intrauterine system is the most effective long-term treatment for primary dysmenorrhea and for menorrhagia. The newer GnRH antagonists (elagolix, relugolix) are used in endometriosis and uterine fibroid-associated pain. The smooth-muscle relaxant uterotropic phloroglucinol is used in France.

For the rare visceral spasm of the achalasia spectrum (oesophageal spasm, nutcracker oesophagus, jackhammer oesophagus), nitrates, calcium channel blockers (nifedipine, diltiazem), sildenafil and the other phosphodiesterase-5 inhibitors, and intramuscular or intra-sphincter onabotulinumtoxinA injection are the medical-treatment options before pneumatic dilatation or peroral endoscopic myotomy is considered.

== Classes indexed ==

By mechanism:

* '''Antimuscarinic''' (cross-indexed under [[:Category:Antimuscarinics|antimuscarinics]]):
** Tertiary amines: [[wikipedia:Atropine|atropine]], [[wikipedia:Hyoscyamine|hyoscyamine]] (Levsin), [[wikipedia:Scopolamine|scopolamine]] (hyoscine hydrobromide)
** Quaternary amines (no blood-brain-barrier penetration): [[Dicyclomine|dicyclomine]] (Bentyl), [[wikipedia:Propantheline|propantheline]], [[wikipedia:Glycopyrrolate|glycopyrrolate]] (Robinul), [[wikipedia:Methscopolamine|methscopolamine]] (hyoscine butylbromide as Buscopan; not marketed in U.S.)
* '''Calcium channel blocker, smooth-muscle-selective''' (mostly European):
** [[wikipedia:Mebeverine|Mebeverine]] (Colofac)
** [[wikipedia:Otilonium bromide|Otilonium]] (Spasmomen)
** [[wikipedia:Pinaverium bromide|Pinaverium]] (Dicetel)
** [[wikipedia:Alverine|Alverine]] (Spasmonal)
* '''Mu/kappa opioid-receptor modulator''' (enteric-nervous-system):
** [[wikipedia:Trimebutine|Trimebutine]] (Modulon; Canada, France)
* '''Direct smooth-muscle relaxant''':
** [[wikipedia:Papaverine|Papaverine]] (intracavernosal in erectile dysfunction; intraoperative vasospasm)
** Drotaverine (No-Spa; Eastern Europe, India)
** Phloroglucinol (Spasfon; France, Belgium)
* '''Plant-derived''':
** [[wikipedia:Peppermint oil|Peppermint oil]] (enteric-coated; IBgard, Pepogest)
** Iberogast (multi-herb extract; Germany)
** Carum / fennel / caraway combinations (over-the-counter European preparations)
* '''NSAIDs''' (for dysmenorrhea; cross-indexed under [[:Category:NSAIDs|NSAIDs]]):
** Ibuprofen, naproxen, mefenamic acid
* '''Other for specific indications''':
** Intramuscular [[wikipedia:Hyoscine butylbromide|hyoscine butylbromide]] (biliary, renal colic; not U.S.)
** Sublingual nitroglycerin (oesophageal spasm, sphincter-of-Oddi dysfunction)
** [[wikipedia:OnabotulinumtoxinA|OnabotulinumtoxinA]] (achalasia injections, oesophageal-spasm injections)

== Notes on scope ==

The boundary of this category is "medicine prescribed primarily to relieve smooth-muscle spasm." The skeletal-muscle relaxants (cyclobenzaprine, methocarbamol, tizanidine, baclofen, dantrolene; the parenteral neuromuscular blockers) are not antispasmodics in this category sense and are listed under [[wikipedia:Muscle relaxant|skeletal-muscle relaxants]] separately. The [[:Category:Bronchodilators|bronchodilators]] act on airway smooth muscle but are categorised by their respiratory indication. The [[:Category:Vasodilators|vasodilators]] act on vascular smooth muscle and are categorised under cardiovascular indications. The medicines for overactive bladder (the antimuscarinics, the beta-3 agonists, onabotulinumtoxinA detrusor injection) are cross-listed at [[:Category:Overactive_bladder_medications|overactive bladder medications]] but are not generally treated as antispasmodics, although they act on detrusor smooth muscle.

== About these pages ==

This category page is an encyclopedia article about its subject. The actual index of medicines belonging to the category is generated automatically by the wiki engine, from category-membership declarations on the individual medicine pages, and appears at the foot of the page below the references.

== References ==

<references/>

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Category:Antispasmodics - Revision history

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