loperamide hydrochloride + simeticone: clinical use

Prescribing considerations

• Confirm that diarrhoea is acute and accompanied by gas-related discomfort; investigate and treat an identifiable underlying cause.
• Assess hydration and electrolyte replacement needs.
• Use cautiously in hepatic impairment because reduced first-pass metabolism may increase CNS toxicity; severe dysfunction requires medical supervision.
• Consider abuse or misuse history and emphasise the cardiac and neurological toxicity of overdose.
• Review interacting CYP3A4, CYP2C8 and P-glycoprotein inhibitors.

Contraindications and cautions

• Age under 12 years
• Hypersensitivity to either active substance or an excipient
• Acute dysentery with blood in stool and high fever
• Acute ulcerative colitis
• Antibiotic-associated pseudomembranous colitis
• Bacterial enterocolitis caused by invasive organisms
• Any situation in which slowing peristalsis should be avoided, including risk of ileus, megacolon or toxic megacolon
• Rare glucose-galactose malabsorption because the formulation contains glucose-containing maltodextrin

Monitoring

• Clinical response and development of new or worsening symptoms
• Fluid and electrolyte status where diarrhoea is severe
• Constipation, ileus or abdominal distension; discontinue promptly if these develop
• CNS toxicity in hepatic impairment
• ECG and CNS/respiratory status following suspected overdose

Clinical pharmacology

Loperamide acts locally at intestinal opioid receptors, reducing propulsive motility and increasing water and electrolyte absorption. It has marked hepatic first-pass metabolism involving CYP3A4 and CYP2C8, and is a P-glycoprotein substrate. Simeticone is chemically inert, acts locally by disrupting foam and is not absorbed.

Formulation and product differences

• The selected product is an uncoated, capsule-shaped tablet containing both active ingredients.
• The tablet marking is not a functional score and should not be used for splitting.
• The formulation contains benzyl alcohol and glucose-containing maltodextrin and is essentially sodium-free.