Senna

Introduction Overview

Generic Name

senna

Brand Name

Senokot

Dosage Form

oral tablet, chewable tablet, liquid formulations

Drug Class

Laxatives

Pharmacokinetics

Absorption:
Senna is administered orally and undergoes limited absorption in the upper gastrointestinal tract. The active compounds in senna, primarily sennosides (anthraquinone glycosides), pass through the stomach and small intestine largely unchanged and reach the colon. There, they are metabolized by colonic bacteria into active anthraquinones such as rheinanthrone, which exert the laxative effect. The rate and extent of absorption depend on gastrointestinal motility and the presence of gut flora. Inter-individual variation in colonic bacterial activity can influence onset and intensity of action.

Distribution:
Following bacterial metabolism in the colon, the active metabolites exert local effects on the colon mucosa and smooth muscle. Systemic absorption is minimal, hence plasma concentrations of active compounds are typically low to negligible. The local nature of senna’s activity limits systemic distribution. Trace amounts that are absorbed may bind to plasma proteins, but pharmacokinetic studies show a minimal systemic load due to extensive first-pass metabolism and fecal elimination.

Metabolism:
Senna’s primary constituents, sennosides A and B, are prodrugs that are metabolized by intestinal bacteria in the colon into anthraquinone derivatives such as rheinanthrone and rhein. These metabolites stimulate the enteric nervous system leading to enhanced peristalsis and laxation. Hepatic metabolism plays a minor role. The enterohepatic recycling of certain metabolites may occur but has limited clinical significance. Microbial metabolism is essential for senna’s laxative effect.

Elimination:
The active anthraquinone metabolites exert local effects and are subsequently eliminated primarily via feces. Some metabolites may be absorbed and disposed of renally either unchanged or as conjugates. Renal elimination of senna metabolites is minor compared to fecal clearance. The pharmacokinetic profile typically results in bowel movement onset within 6 to 12 hours after ingestion. Prolonged use, overdose, or impaired renal function can alter elimination and increase side effect risk.

Dosage Forms

Available Dosage Forms:
Senokot is available in multiple oral formulations including conventional tablets, chewable tablets, and liquid solutions. Specific product lines include Senokot regular strength tablets, Senokot Extra Strength tablets, Senokot Laxative Gummies (flavors such as Blue Pomegranate and Mixed Berries), and Senokot Tea. Dosage strengths available are typically 8.6 mg sennosides per tablet.

Dosages for Adults and Adolescents:
The recommended adult dose is typically 1 to 2 tablets once daily at bedtime or as directed by a healthcare provider. Maximum duration should not exceed one week without medical consultation. For adolescents and children over 2 years of age, the dose must be adjusted carefully and used under medical supervision. Chewable tablets should be thoroughly chewed before swallowing; liquid preparations should be measured with the supplied device.

Specific Patient Populations:
Senna use in children under 2 years is generally not recommended due to limited safety data. Pregnant and breastfeeding women should consult healthcare providers before use. Dosing adjustments or alternative therapies may be necessary for patients with existing electrolyte imbalances, renal impairment, or gastrointestinal obstruction.

Detailed Dosage Forms and Strengths:
- Senokot Tablets: 8.6 mg sennosides per tablet
- Senokot Extra Strength Tablets: higher concentration sennosides per tablet
- Senokot Chewable Tablets: designed for easier administration, same active dose range
- Senokot Laxative Gummies: fruit-flavored chewables containing senna extracts
- Senokot Liquid: herbal syrup measured with specific dosing device
- Senokot Tea: herbal infusion containing senna leaves for oral administration

Mechanism Of Action

Senna exerts its laxative effect primarily through the stimulation of colonic motility and promotion of water and electrolyte secretion in the large intestine. The primary active components, sennosides, are anthraquinone glycosides that reach the colon largely unchanged and are metabolized by colonic bacteria into active anthraquinones such as rheinanthrone.

These active metabolites interact with the enteric nervous system, stimulating the nerve endings and triggering peristalsis—rhythmic contractions of the intestinal smooth muscle that propel fecal matter toward defecation. Additionally, senna promotes secretion of water and electrolytes into the bowel lumen, softening the stool and facilitating easier passage.

At the cellular level, sennosides induce mild inflammation of the mucosal lining leading to increased secretion and decreased absorption, enhancing stool liquidity. This mechanism of action contrasts with bulk-forming laxatives that increase fecal volume and osmotic laxatives that retain water via osmotic gradients. Senna is classified as a stimulant laxative, and its onset is typically 6 to 12 hours post ingestion, consistent with colonic transit time.

Clinical studies demonstrate that senna is effective for relieving occasional constipation and preparing the bowel pre-procedure. However, prolonged use may lead to electrolyte disturbances and potential colonic dependency. Compared to other stimulant laxatives like bisacodyl, senna has a similar mechanism but is derived from botanical origin with a favorable safety profile when used correctly.

Pharmacological Actions

Stimulates colonic peristalsis via enteric nervous system activation
Promotes electrolyte and water secretion into the intestinal lumen
Softens stool by increasing luminal fluid content
Acts as a stimulant laxative facilitating bowel movement within 6-12 hours
Metabolized by colonic bacteria into active anthraquinone compounds
Locally active in the colon with minimal systemic absorption
Induces mild mucosal irritation to enhance secretory activity
Useful in bowel preparation prior to colonoscopic procedures
Helps alleviate occasional constipation in adults and children over 2 years
Has minimal systemic toxicity when used at recommended dosages
Can lead to electrolyte imbalances if overused or in susceptible populations
Potentially effective as alternative medicine herbal laxative
May alter intestinal microbiota through its metabolic requirement
Non-opioid mechanism avoids interaction with opioid receptors
Herbal origin with well-characterized active components (sennosides)

Therapeutic Or Clinical Uses

Treatment of occasional constipation in adults and children aged 2 years and over
Bowel evacuation prior to diagnostic procedures such as colonoscopy
Alternative medicine use as a natural laxative herbal supplement
Adjunct therapy to soften stool and facilitate bowel movements
Relief from symptoms of infrequent or difficult defecation
Temporary use to improve gastrointestinal transit and alleviate discomfort
Off-label uses include aiding in irritable bowel syndrome symptom management
Used to reduce straining during defecation in hemorrhoid patients
Part of bowel cleansing regimens where stimulant laxatives are indicated
Management of opioid-induced constipation in some clinical settings
May be combined with stool softeners for enhanced laxative effect
Supports intestinal motility in functional bowel disorders
Short-term treatment option in chronic constipation under supervision
Employed as an herbal remedy in traditional medicine practices
Used for patients who prefer botanical or non-pharmacologic laxatives

Side Or Adverse Effects

Abdominal cramping and stomach discomfort
Diarrhea or urgent need to defecate
Nausea and gas
Urine discoloration due to excretion of senna metabolites
Potential for rectal bleeding if used excessively or underlying conditions present
Risk of hypokalemia (low blood potassium) causing muscle cramps and weakness
Electrolyte imbalances leading to cardiac arrhythmias in severe cases
Dependence with prolonged use leading to decreased bowel function
Possible allergic reactions including hives and swelling
Rare systemic toxicity when overdosed
Dehydration if diarrhea is severe
Potential exacerbation of inflammatory bowel disease symptoms
May cause abdominal distension and bloating
Possible interaction-related side effects when combined with other drugs
Rare reports of liver toxicity with prolonged high-dose usage

Precautions

Do not use if allergic to senna or any of its components
Avoid use in patients with diarrhea, hemorrhoids, or abdominal pain
Contraindicated in intestinal obstruction or inflammatory bowel disease
Use cautiously in patients with electrolyte imbalances, particularly low potassium
Avoid in cases of appendicitis or suspected acute abdominal conditions
Consult healthcare provider before use during pregnancy or breastfeeding
Not recommended for children under 2 years without medical supervision
Avoid concomitant use with other stimulant laxatives unless directed by a physician
Limit use duration to less than one week unless supervised by a doctor
Avoid use with mineral oil as it may alter absorption
Monitor for signs of dependence with long-term use
Do not exceed recommended dosage to prevent serious side effects
Store away from moisture and heat to preserve efficacy
Discontinue if no bowel movement occurs within 12 hours of use
Keep healthcare providers informed about all herbal supplements and medicines being taken

Warnings

Follow all directions on package labeling precisely
Inform all healthcare providers of all medical conditions and medications
Stop use and seek immediate medical attention if rectal bleeding occurs
Discontinue if no bowel movement within 12 hours after use
Risk of serious electrolyte disturbances such as hypokalemia
Risk of allergic reaction including anaphylaxis is possible
Avoid long-term or excessive use due to risk of dependence and adverse effects
Not approved by FDA for treatment of medical conditions; use with caution
Do not use if you have intestinal blockage or severe abdominal pain
Pregnant or breastfeeding women should seek medical advice prior to use
Avoid mixing different senna forms (tablets, liquids, teas) simultaneously
Do not use with other laxatives unless prescribed by a physician
May impair absorption of other medications if taken within 2 hours
Potential contamination risk in unregulated herbal products; use reliable sources
Report adverse effects promptly to medical professionals or FDA

Contraindication

Known allergy or hypersensitivity to senna or related compounds
Patients with diarrhea as a presenting symptom
Hemorrhoids with active bleeding
Conditions involving severe stomach pain of unknown origin
Intestinal obstruction or blockage
Inflammatory bowel diseases such as Crohn’s disease or ulcerative colitis
Acute appendicitis or suspicion thereof
Patients with electrolyte imbalances without correction
Use not recommended in children under 2 years of age
Conditions involving nausea and vomiting without diagnosis
Concomitant use with other stimulant laxatives without medical supervision
Severe dehydration or fluid imbalance states
Patients taking medications with a narrow therapeutic window sensitive to potassium shifts
Known or suspected intestinal stenosis or structural anomalies
Patients with compromised renal or hepatic function without medical approval

Drug Interactions

Warfarin (Coumadin, Jantoven) – may increase bleeding risk by altering vitamin K metabolism or electrolyte balance
Diuretics (water pills) – increased risk of hypokalemia when combined with senna
Mineral oil – senna may affect absorption and efficacy of mineral oil
Other laxatives – additive effects increasing risk of electrolyte imbalance and dehydration
Licorice, horsetail, aloe, buckthorn, gossypol, rhubarb – herbal supplements that can lower potassium and increase risk of hypokalemia
Medications with narrow therapeutic range affected by electrolytes (e.g., digoxin) – risk of toxicity with potassium disturbances
Oral medications with absorption dependent on gastrointestinal transit time – senna may reduce absorption if taken concomitantly
Drugs metabolized by cytochrome P450 enzymes – unlikely but possible interaction through altered GI motility
Potassium supplements or salt substitutes – combined effect on potassium levels requires monitoring
Anticoagulants or antiplatelet agents – use with caution due to potential increased bleeding
Agents that cause dehydration (e.g., laxatives, diuretics, sweating-inducing drugs) – when combined with senna, increase risk of volume depletion
Herbal products containing stimulant laxatives – cumulative additive effects
Immunosuppressants with narrow therapeutic index – altered absorption due to diarrhea
Drugs affecting intestinal flora may alter senna metabolism and efficacy
Electrolyte-altering drugs that may exacerbate imbalances when combined with senna

Preparations Of The Drug

Senokot regular strength tablets containing 8.6 mg sennosides per tablet
Senokot Extra Strength tablets with higher sennoside content for enhanced effect
Senokot chewable tablets designed for pediatric or ease-of-use dosing
Senokot Laxative Gummies in assorted fruit flavors for palatable administration
Senokot Tea composed of senna leaf extract for herbal infusion
Senokot liquid formulations supplied with calibrated dosing device
Senokot S formulation designed for bowel preparation procedures
Herbal supplements standardized for sennoside content
Over-the-counter combined products containing senna and stool softeners like docusate
Combination kits for colonoscopy preparation including senna-based laxatives
Bulk powder or granule forms (less commonly used)
Formulations incorporating senna with other herbal laxative agents or fibers
Topical rectal formulations generally not applicable for senna
Products marketed under various brand names with standardized senna extracts
Non-FDA approved herbal senna supplements with variable content and potency