Senokot - Drug Monograph

Introduction

Senokot is a widely used over-the-counter laxative medication containing sennosides, which are derived from the senna plant (Cassia senna or Cassia angustifolia). It is classified as a stimulant laxative and is commonly used for the relief of occasional constipation. Senokot has been used medicinally for centuries and remains one of the most popular OTC constipation remedies worldwide.

Mechanism of Action

Sennosides are prodrugs that undergo hydrolysis by colonic bacteria to form the active metabolites rhein-anthrone. These active compounds work through two primary mechanisms: 1. Stimulation of colonic peristalsis by direct action on the intestinal mucosa 2. Inhibition of water and electrolyte absorption in the large intestine 3. Increased prostaglandin synthesis, which enhances intestinal motility

The result is increased intestinal motility and decreased colonic absorption, leading to softer stools and bowel movements typically within 6-12 hours after administration.

Indications

• Short-term treatment of occasional constipation
• Bowel evacuation prior to diagnostic procedures (when recommended by healthcare provider)
• Management of constipation in specific patient populations (e.g., postoperative, opioid-induced constipation)

Dosage and Administration

• Tablets: 2-4 tablets (8.6 mg sennosides each) once daily at bedtime
• Granules: 1 teaspoon (approximately 15 mg sennosides) once daily at bedtime

• ½ the adult dose, adjusted based on response and provider recommendation

• Geriatric patients: Start with lowest effective dose
• Renal impairment: Use with caution
• Hepatic impairment: Use with caution
• Pregnancy: Generally considered safe for short-term use (Category C)

• Take with a full glass of water
• Typically administered at bedtime for morning bowel movement
• Should not be used for more than 7 days without medical supervision

Pharmacokinetics

Contraindications

• Known hypersensitivity to sennosides or any component of the formulation
• Acute surgical abdomen
• Appendicitis or symptoms suggesting appendicitis
• Intestinal obstruction
• Severe abdominal pain
• Inflammatory bowel disease (e.g., Crohn's disease, ulcerative colitis)
• Severe dehydration
• Rectal bleeding of unknown origin

Warnings and Precautions

• Not for long-term use (beyond 1 week) without medical supervision
• May cause electrolyte imbalance with prolonged use
• Use with caution in patients with renal impairment
• May cause dependence with chronic use (cathartic colon)
• Not recommended for children under 2 years of age
• Discontinue use if severe abdominal pain, cramping, or rectal bleeding occurs
• Use cautiously in patients with cardiovascular conditions due to potential electrolyte changes

Drug Interactions

• Diuretics: Increased risk of electrolyte imbalance
• Corticosteroids: Enhanced potassium depletion
• Antiarrhythmic drugs: Electrolyte changes may affect drug efficacy
• Digoxin: Hypokalemia may increase digoxin toxicity risk
• Other laxatives: Additive effects may cause excessive bowel activity

• May affect absorption of other oral medications due to accelerated GI transit

Adverse Effects

• Abdominal discomfort/cramping
• Diarrhea
• Nausea
• Flatulence

• Electrolyte abnormalities (hypokalemia, hypocalcemia)
• Urine discoloration (pink-red or yellow-brown)
• Melanosis coli with long-term use
• Laxative dependence

• Severe allergic reactions
• Severe electrolyte imbalance
• Stevens-Johnson syndrome (very rare)

Monitoring Parameters

• Bowel movement frequency and consistency
• Electrolyte levels with prolonged use
• Signs of dehydration
• Abdominal pain or discomfort
• Development of tolerance or dependence
• Urine and stool characteristics
• Weight changes with chronic use

Patient Education

• Use only as directed for occasional constipation
• Drink plenty of fluids (6-8 glasses daily) while using this medication
• Do not use for more than 7 days without consulting healthcare provider
• Expect bowel movement within 6-12 hours after dosing
• Report severe abdominal pain, rectal bleeding, or no bowel movement after use
• This medication may cause urine to turn pink-red or yellow-brown
• Include fiber-rich foods and maintain physical activity for bowel regularity
• Do not use if you are experiencing nausea, vomiting, or abdominal pain
• Store at room temperature away from moisture and heat

References

1. National Institutes of Health. Senna. In: LiverTox: Clinical and Research Information on Drug-Induced Liver Injury. 2017. 2. American Gastroenterological Association. Technical Review on Constipation. Gastroenterology. 2013;144(1):218-238. 3. Müller-Lissner SA, et al. Myths and Misconceptions About Chronic Constipation. Am J Gastroenterol. 2005;100(1):232-242. 4. Prescriber's Digital Reference. Sennosides - Drug Summary. 2023. 5. World Health Organization. WHO Model Formulary. 2021 Edition. 6. Brenner DM, et al. Chronic Constipation. Gastroenterol Clin North Am. 2021;50(2):215-230. 7. FDA OTC Monograph for Laxative Drug Products. 21 CFR Part 334. 8. Leung L, et al. American College of Gastroenterology Clinical Guideline: Management of Constipation. Am J Gastroenterol. 2023;118(5):785-804.