Dulcolax - Drug Monograph

Introduction

Dulcolax (bisacodyl) is a widely used stimulant laxative medication indicated for the treatment of constipation and for bowel cleansing prior to medical procedures. First introduced in the 1950s, it remains one of the most commonly used over-the-counter and prescription laxatives worldwide. This monograph provides comprehensive clinical information about bisacodyl for healthcare professionals.

Mechanism of Action

Bisacodyl exerts its laxative effect through direct stimulation of the colonic mucosa and myenteric plexus. The drug undergoes hydrolysis in the small intestine to its active metabolite, bis-(p-hydroxyphenyl)-pyridyl-2-methane (BHPM), which acts on the enteric nerves to stimulate colonic peristalsis. This stimulation increases intestinal motility and promotes water and electrolyte secretion into the colonic lumen, resulting in accelerated colonic transit and defecation typically within 6-12 hours after oral administration.

Indications

• Treatment of occasional constipation
• Bowel evacuation prior to surgical procedures, radiological examinations, or endoscopic procedures
• Management of constipation in patients with opioid-induced constipation (off-label)
• Bowel preparation regimens in combination with other laxatives

Dosage and Administration

• Oral tablets: 5-15 mg once daily (maximum 30 mg daily)
• Rectal suppositories: 10 mg once daily

• Oral tablets: 5-10 mg once daily
• Rectal suppositories: 5-10 mg once daily

• Renal impairment: Use with caution; no specific dosage adjustment recommended
• Hepatic impairment: Use with caution; no specific dosage adjustment recommended
• Elderly: Consider lower starting doses due to increased sensitivity
• Pregnancy: Category B - generally considered safe for short-term use

Administration instructions: Oral tablets should be swallowed whole with water, not crushed or chewed. Avoid taking within 1 hour of antacids or dairy products as this may cause premature dissolution. Rectal suppositories should be inserted completely into the rectum.

Pharmacokinetics

Contraindications

• Known hypersensitivity to bisacodyl or any component of the formulation
• Acute surgical abdomen
• Appendicitis symptoms
• Acute inflammatory bowel diseases
• Severe abdominal pain with nausea and vomiting
• Intestinal obstruction
• Severe dehydration

Warnings and Precautions

• Prolonged use may lead to laxative dependence and electrolyte abnormalities
• Risk of hypokalemia with chronic use
• May cause abdominal cramps, discomfort, or pain
• Rectal administration may cause local irritation
• Not recommended for use beyond 7 days without medical supervision
• Use with caution in patients with electrolyte imbalances
• Avoid in patients with renal impairment due to potential electrolyte disturbances
• May cause false-positive results for phenolphthalein in stool tests

Drug Interactions

• Antacids: Concomitant administration may cause premature dissolution of enteric coating leading to gastric irritation
• Diuretics: Increased risk of hypokalemia when used concurrently
• Corticosteroids: Enhanced potassium depletion when used with bisacodyl
• Digoxin: Hypokalemia may increase digoxin toxicity risk
• Other laxatives: Increased risk of electrolyte abnormalities when used concomitantly

Adverse Effects

• Abdominal discomfort/cramping
• Nausea
• Diarrhea
• Rectal irritation (with suppositories)
• Weakness

• Electrolyte disturbances (hypokalemia, hypocalcemia)
• Dizziness
• Allergic reactions
• Rectal burning (with suppositories)

• Severe electrolyte imbalances
• Stevens-Johnson syndrome (rare)
• Allergic reactions including anaphylaxis
• Ischemic colitis (rare case reports)

Monitoring Parameters

• Electrolyte levels (particularly potassium) with prolonged use
• Hydration status
• Bowel frequency and consistency
• Abdominal symptoms
• Signs of laxative dependence with chronic use
• Patient weight in cases of prolonged use
• Renal function in patients with pre-existing renal impairment

Patient Education

• Use only as directed for short-term relief of constipation
• Swallow tablets whole with water; do not crush or chew
• Avoid taking within 1 hour of antacids or milk products
• Expect bowel movement within 6-12 hours after oral administration or 15-60 minutes after rectal administration
• Report persistent constipation, rectal bleeding, or severe abdominal pain
• Do not use for more than 7 days without consulting healthcare provider
• Increase dietary fiber and fluid intake as primary constipation management
• Be aware that prolonged use may lead to dependence on laxatives
• Store at room temperature away from moisture

References

1. American Gastroenterological Association. (2013). Guidelines on the management of constipation. Gastroenterology, 144(1), 211-217. 2. Portalatin M, Winstead N. (2012). Medical management of constipation. Clin Colon Rectal Surg, 25(1), 12-19. 3. Müller-Lissner SA, et al. (2010). Myths and misconceptions about chronic constipation. Am J Gastroenterol, 105(11), 2328-2337. 4. Brenner DM, et al. (2020). Efficacy and safety of bisacodyl in the treatment of constipation: a systematic review. J Clin Gastroenterol, 54(10), 851-867. 5. FDA-approved prescribing information for Dulcolax (bisacodyl). 6. World Gastroenterology Organisation. (2007). World Gastroenterology Organisation Practice Guidelines: Constipation. 7. Lee-Robichaud H, et al. (2011). Lactulose versus polyethylene glycol for chronic constipation. Cochrane Database Syst Rev, (7):CD007570. 8. Emmanuel A, et al. (2017). Pharmacological management of constipation. Neurogastroenterol Motil, 29(2):e12953.