Antispasmodic drugs

Antispasmodic drugs

1. Anti-spasmodic drugs D rugs used to treat symptoms such as pain and spasm in irritable bowel syndrome. Classification: Antimuscarinics / Anticholinergics : Hyoscine Butylbromide , Atropine, Dicyclomine , Propantheline Smooth muscle relaxants: Drotaverine , A lverine , M ebeverine , Peppermint oil

2. Antispasmodics are given for abdominal pain , IBS symptoms. There are two main classes of antispasmodic , the antimuscarinic drugs and drugs that are direct smooth muscle relaxants. Antimuscarinic drugs These drugs block cholinergic transmission at parasympathetic postganglionic nerve endings and cause smooth muscle to relax. The synthetic antimuscarinics dicyclomine and propantheline are probably the most useful in IBS, but therapeutic efficacy is often limited by other anticholinergic effects. The drugs are contraindicated in patients with glaucoma and prostatism , and should be avoided in patients with gastro-oesophageal reflux .

3. Direct smooth muscle relaxants Mebeverine is a reserpine derivative that has a direct effect on colonic muscle activity, especially, it appears, on colonic hypermotility . As it does not possess antimuscarinic activity, it does not exhibit the troublesome effects of that group of drugs. Alverine and peppermint oil also have direct smooth muscle relaxing activity .

4. Anti spasmodics are commonly used in: To help relieve some of the symptoms of IBS such as spasm (colic), bloating and abdominal pain To reduce the movement ( motility) of the intestine Overactive bladder Movement problems in Parkinson's disease Diarrhoea Motion sickness Nausea  and/or  vomiting Muscle spasms Chronic obstructive pulmonary disease ( COPD) Asthma

5. MECHANISM: Movement of food along the gut occurs because of the regular relaxation and contraction of muscles of gut. In conditions such as IBS these muscle contractions can occur too often or be painful, causing symptoms such as pain and bloating Anti muscarinics work by attaching to the muscarinic receptors and stopping the chemicals to act & make the muscle contract. Reducing the muscle contractions in this way often helps to relieve some of the symptoms caused by IBS

6. Hyoscine B utylbromide MOA: A lso known as   scopolamine butylbromide and sold under brandname   Buscopan has anticholinergic action . Its high affinity for muscarinic receptors located on the smooth-muscle cells of the GI tract  exerts a smooth-muscle relaxing/spasmolytic effect. Indications (Dosage 20-40mg oral, 20mg/ml Inj ) crampy  abdominal pain esophageal spasms renal colic bladder spasms It is also used to improve respiratory secretions at the end of life Hyoscine butylbromide can be taken by mouth , injection into a muscle, or into a vein Side effects: sleepiness , vision changes, dry mouth, rapid heart rate, triggering of  glaucoma and severe allergies. Sleepiness however, is uncommon .

7. Dicyclomine : Has direct smooth muscle relaxant action & weak anti cholinergic Exerts anti spasmodic action Also has anti-emetic property Indications: Morning sickness Motion sickness Dysmenorrhoea Irritable bowel disease Dose: 20 mg oral/ i.m children 5-10mg

8. Contraindications: Paralytic ileus Myasthenia gravis Pyloric stenosis Enlargement of the prostate Pregnancy Lactating mother ADRs Flatulence bloating(wind) Heart burn Constipation Dry mouth

9. Drotaverine : A novel non anticholiergic smooth muscle relaxant Exerts anti spasmodic action Used orally MOA Inhibits phosphdiesterase-4 selective for smooth muscle Elevation of cAMP / cGMP attends smooth muscle relaxation

10. Drotaverine has spasmolytic and vasodilating action. It exerts its action by inhibiting phosphodiesterase enzyme IV. This will leads to a decrease in cyclic AMP level and reduction in calcium ions (Ca2+). The reduction of calcium ions will dilates the unstipped muscles and blood vessels strongly and relieves spasm of smooth muscles.

11. Indications: Intestinal, biliary , renal colics Irritable bowel syndrome Uterine spasm ADR: Dose: Headache 40-80 mg tds Dizziness Drotin Constipation Flushing Fall in BP can occur on iv inj