ICD-10 Specific code K58.0: Irritable bowel syndrome with diarrhoea

Atropine is an antimuscarinic agent which competitively antagonises acetylcholine at postganglionic nerve endings, thus affecting receptors if the exocrine glands, smooth muscle, cardiac muscle and the central nervous system.

Butylscopolamine is an antispasmodic agent which relaxes smooth muscle of the organs of the abdominal and pelvic cavities. It is believed to act predominantly on the intramural parasympathetic ganglia of these organs.

Codeine is a centrally acting weak analgesic. Codeine exerts its effect through μ opioid receptors, although codeine has low affinity for these receptors, and its analgesic effect is due to its conversion to morphine. Codeine, particularly in combination with other analgesics such as paracetamol, has been shown to be effective in acute nociceptive pain. The anti-tussive activity of codeine is probably due to its depressant effect on the medullary cough centre in the brain.

Diosmectite is a natural aluminomagnesium silicate clay with a lamellar, non-fibrous crystalline structure that gives it strong adsorbent properties. Diosmectite has demonstrated efficacy in the treatment of acute watery diarrhoea in children.

Mebeverine is a musculotropic antispasmodic with a direct action on the smooth muscle of the gastrointestinal tract, relieving spasm without affecting normal gut motility.

Opium alkaloids (opioids and isoquinoline derivatives) induce constipation, euphoria, analgesia and sedation dependent on the dose and derivative. The constipating effect is caused by inhibition of the intestines' peristalsis.