glycerol: clinical use

Prescribing considerations

• Confirm whether relief is required for a dry cough or constipation; oral and rectal products have different actions and licensing.
• Assess persistent or recurrent symptoms for an underlying cause.
• Check product-specific age restrictions and select the appropriate suppository size.
• Review oral-product excipients, particularly maltitol, sorbitol, sodium benzoate and propylene glycol.
• One selected suppository warns that use may interfere with glucose control in people with diabetes.

Contraindications and cautions

• Hypersensitivity to glycerol or any product excipient.
• Intestinal obstruction or blockage for the selected suppository.
• Hereditary fructose intolerance where an oral product contains sorbitol or maltitol.
• Adult-size suppositories are unsuitable for children and infants.

Monitoring

• Clinical response and persistence or worsening of symptoms.
• Rectal irritation, abdominal cramping and diarrhoea.
• Glucose control where relevant in a person with diabetes using the selected suppository.

Clinical pharmacology

Oral glycerol is a locally acting demulcent. Rectal glycerol is poorly absorbed and has osmotic, lubricating, stool-softening and mild local stimulant effects.

Formulation and product differences

• Oral products are viscous syrups or solutions intended to soothe the throat; excipients and minimum licensed ages vary.
• Suppositories are rectal preparations containing glycerol with gelatin and water, supplied in age- or size-specific presentations.
• Selected Tixylix products are not recommended below their stated minimum age; the selected Covonia product is unsuitable for children under one year.
• The sugar-free Covonia formulation still contains polyols and is unsuitable in hereditary fructose intolerance.

Oral solution

Route: Oral

Strengths: 1.36 g/5 mL

Suppository

Route: Rectal

Strengths: 1 g, 2 g, 4 g