Digestive System and Drugs

Mouth / Oral Cavity

Begins digestion with mechanical processing and saliva secretion

• Saliva moistens food and starts carbohydrate digestion with amylase.

• Disorders such as cold sores, canker sores, and infections can disrupt digestion

Pharynx

Passageway for food to the esophagus

Esophagus

Moves food to the stomach via peristalsis

Esophageal Sphincters

• Upper Esophageal Sphincter: Prevents aspiration of food and liquids into the lungs

• Lower Esophageal Sphincter: Prevents reflux of stomach contents back into the esophagus

• Malfunctioning sphincters may cause conditions such as GERD, esophagitis, and hiatal hernia

Stomach

The stomach plays a critical role in digestion through mechanical and chemical processes

• Mixes food with digestive juices to form chyme

• Four main parts:

  • Cardia

  • Fundus

  • Body

  • Pylorus.

• Regulated by the lower esophageal sphincter and pyloric sphincter

• Produces hydrochloric acid (HCl) and digestive enzymes

Small Intestine

Absorbs 90-95% of nutrients

• Consists of the duodenum, jejunum, ileum, and ileocecal valve.

• Digestive juices from the liver, gallbladder, and pancreas aid in digestion.

  • Pancreatic enzymes (lipase, protease, amylase) break down fats, proteins, and carbohydrates

• Villi increase surface area for absorption, and blood capillaries absorb nutrients

Large Intestine

Absorbs water and electrolytes, forms feces

• contains bacteria that help with fermentation as well .

• It also absorbs vitamin K and B vitamins

• Waste products move toward the rectum for elimination.

• Common disorders include IBS

  • Lifestyle changes like diet, hydration, and stress management can help manage IBS

Anus

Responsible for defecation

Accessory Organs of the Digestive System

• Teeth: Bite and chew food (mastication)

• Tongue: Aids in mastication and swallowing

• Salivary Glands: Secrete saliva with enzymes for digestion

• Pancreas: Produces digestive enzymes

• Liver: Produces bile for fat digestion

• Gallbladder: Stores and concentrates bile

The Digestion Process

1. Ingestion: Food enters through the mouth

2. Mechanical Digestion: Chewing and churning of food

3. Chemical Digestion: Enzymes break down food into nutrients

4. Absorption: Nutrients absorbed in small intestine

5. Waste Elimination: Unabsorbed material is excreted as feces

3 Phases of Digestion

1. Cephalic Phase: begins with the brain, sensory stimulation triggers digestion.

2. Gastric Phase: food enters the stomach, stimulating acid and enzyme production.

3. Intestinal Phase: digestion continues in the small intestine for nutrient absorption.

Role of Hydrochloric Acid (HCl)

• HCl is essential for digestion, creating an acidic environment for food breakdown.

• Supports protein digestion by activating pepsinogen to pepsin.

• Helps absorb essential minerals and eliminate harmful microorganisms.

Stomach Protection Mechanisms

• Goblet cells secrete mucus to protect stomach lining

• Prostaglandin E2 stimulates mucus production and maintains perfusion

• Imbalance can lead to gastritis, ulcers, and complications requiring medication

Common GI Conditions and Treatments

• Conditions: GERD, peptic ulcers, IBS, Crohn's disease, pancreatitis, liver disease, hemorrhoids, cancer.

• Symptoms: Nausea, vomiting, dyspepsia, heartburn, diarrhea, constipation, abdominal pain, bloating.

• Treatments: Antiemetics, antidiarrheals, laxatives, IBS medications, antacids, histamine receptor antagonists, proton pump inhibitors, antibiotics

Common Digestive Enzymes in Mouth, Stomach, Pancreas, and Small Intestine

• Mouth: Salivary amylase breaks down starches into disaccharides.

• Stomach: Pepsin breaks down proteins.

• Pancreas: Amylase (starches), trypsin/chymotrypsin (proteins), lipase (fats).

• Small intestine: Maltase, sucrase, lactase break down sugars; peptidase breaks down proteins.

Clinical Considerations for GI Health

When assessing a client’s GI health, consider:

• Dietary habits, food allergies, and intolerances

• Use of nutritional supplements

• Oral health and hygiene

• Changes in appetite or bowel movements

• Hydration, exercise, and weight changes

• Preventive care like regular colonoscopies is also important

GI Disorder Drugs

• Antiemetics

• Antidiarrheals

• Laxatives and Stool Softeners

Antiemetics

Drugs that manage nausea and vomiting by modulating neurotransmitter receptor sites to reduce the hyperactivity of the vomiting reflex in the brain

• Localized antiemetics work at the site of acid production.

• Centrally acting antiemetics block the chemoreceptor trigger zone (CTZ) or suppress the vomiting center (VC)

• Classes within antiemetics:

  • Phenothiazines

  • Antihistamines

  • Serotonin Receptor Antagonists

  • Anticholinergics

  • Cannabinoids

• Prototype drug: Chlorpromazine

Chlorpromazine

Phenothiazine drug (antiemetic)

• MoA: Suppresses the chemoreceptor trigger zone and blocks the postsynaptic dopamine receptors in the brain, causing an antiemetic effect

• Indication: Nausea and vomiting, Psychotic disorders

• Contraindications: Hypersensitivity, in a coma, or with use of CNS depressants, pregnancy concerns

• Interactions: CNS depressants, anticonvulsants

Adverse Effects of Chlorpromazine

• Drowsiness

• Dry mouth

• Constipation

• Dizziness

• Hypotension

• Urinary retention

• Some antiemetics cause extrapyramidal symptoms like tardive dyskinesia (kinda like facial tourettes)

Nursing Considerations for Chlorpromazine

• Assess client history, allergies, and drug interactions before administration.

• Monitor for adverse effects (sedation, extrapyramidal symptoms, hypotension).

• Educate clients on side effects and safety precautions (e.g., fall risks).

• Increase their dietary intake of fiber and increase fluid intake to help reduce the risk of constipation

• don’t drive due to drowsiness effects

Diarrhea

Diarrhea involves frequent, loose, watery stools.

• It can be acute (1–2 days) or chronic (lasting weeks).

• Symptoms: abdominal distress, cramping, bloating, nausea, urgency.

• Serious concern: dehydration and bloody stools.

• Treatment aims to slow intestinal motility but should be avoided if infection is suspected

Antidiarrheals

• These medications activate opioid Mu-receptors to slow intestinal motility

• Used cautiously to prevent CNS depression and euphoria at high doses.

• Prototype Drug: Diphenoxylate with Atropine Sulfate

Diphenoxylate with Atropine Sulfate

A synthetic narcotic that reduces intestinal movement

• Combined with atropine to prevent abuse

• MoA: Reduces peristaltic activity and motility by inhibiting mucosal receptors responsible for peristatic reflexes, thereby stopping or reducing diarrhea

• Indication: Adjunctive therapy in management of diarrhea

• Contraindication: Hypersensitivity, Diarrhea associated pseudomonas enterocolitis, Obstructive jaundice, Pediatric clients under age 6

• Interactions: Caffeine, CNS Depressants

Adverse Effects of Diphenoxylate with Atropine Sulfate

• Blurred vision

• Dry mouth

• Urinary retention

• Tachycardia

• Drowsiness

• Dizziness

• Nausea / Vomiting

• Pupil Constriction

• Constipation

Nursing Considerations for Diphenoxylate with Atropine Sulfate

• Monitor for dehydration: skin turgor, urine output, vital signs.

• Educate clients on side effects like constipation, dizziness, and blurred vision.

• Encourage hydration and fall precautions due to dizziness and sedation.

• Report blurred vision, severe abdominal pain, or bloody stools immediately.

• Avoid caffeine as it increases GI motility.

• Do not drive or operate heavy machinery due to potential drowsiness.

Laxatives and Stool Softeners

Will focus on bulk-forming laxatives

• relieve constipation within 24–72 hours by supplying the colon with an increase in dietary fiber

• It is imperative that these products are taken with an adequate amount of water

• Prototype: Psyllium

Constipation

Constipation involves difficult stool evacuation, often due to low fiber intake, dehydration, or medications

• Treatment: increase fiber, hydration, and exercise.

• Laxatives can help but should not be used long-term.

Psyllium

Bulk-forming laxative

• MoA: Adds bulk to stool through water absorption, which promotes peristalsis and natural elimination

• Indication: Short-term relief of occasional constipation

• Contraindication: Hypersensitivity, GI Obstruction

• Take with lots of fluids*

Adverse Effects of Psyllium

• Abdominal cramping

• Diarrhea

• Electrolyte imbalances

• Rectal irritation

• /bloating

Nursing Considerations of Psyllium

• Assess medical history and bowel habits.

• Educate the client regarding laxative and stool effects, such as abdominal cramping, diarrhea, and rectal irriation.

• Monitor electrolyte levels, particularly sodium and potassium

• Educate patients on hydration, fiber intake, and short-term use of laxatives

• Increase fiber and hydration.

• Report severe symptoms like muscle weakness, numbness, or severe cramps.

• Avoid long-term use to prevent dependency.

Hyperacidity & Antiulcer Drugs

• Antacids

  • Calcium Carbonate

• Histamine Blockers

  • Cimetidine

• Proton-Pump Inhibitors

  • Omeprazole

• Mucosal Protectants

  • Sucralfate

Calcium Carbonate

Antacid

• MoA: Decreases gastric acidity and inhibits proteolytic action of pepsin on gastric mucosa

• Indication: To manage GI hyperacidity conditions such as heartburn, acid indigestion, sour stomach, upset stomach

• Contraindications: Hypersensitivity

• Interactions: Digoxin, Magnesium-containing agents

Adverse Effects of Calcium Carbonate

• Constipation

• Flatulence

• Rebound hyperacidity

• Electrolyte imbalances (hypercalcemia)

Nursing Considerations of Calcium Carbonate

• Monitor fluid intake and urine output.

• Encourage reporting of severe adverse reactions like muscle twitching, tetany, edema, or bone pain

• Chew tablets thoroughly and drink 8 ounces of water.

• Shake liquid antacids before use.

• Take 1 hour before or 2 hours after other medications.

• Do not use for more than 2 weeks without medical advice

Cimetidine

H-2 Receptor Agonist

• MoA: Blocks H2 receptors, thereby suppressing gastric acid secretion, and lowers the hydrogen ion concentration in the stomach

• Indication: treats GERD, ulcers, and Zollinger-Ellison syndrome

• Contraindications: Hypersensitivity

• Interactions: Warfarin

Adverse Effects of Cimetidine

• Diarrhea

• headaches

• mental confusion

• gynecomastia

• neutropenia

• bradycardia

• rash

Omeprazole

Proton Pump Inhibitor

• MoA: Suppresses gastric acid secretion by inhibiting the proton pump

• Indications: GERD, peptic ulcers, and stress ulcer prophylaxis, heartburn, erosive esophagitis

• Contraindications: Hypersensitivity

• Interactions: Amoxicillin, Warfarin

Adverse Effects of Omeprazole

• Headache

• dizziness

• nausea

• vomiting

• abdominal pain

• diarrhea

• increased risk of infections

Nursing Considerations for Histamine Blockers and Proton Pump Inhibitors:

• Assess medical history and allergies.

• Educate about short-term use (4-8 weeks).

• Monitor for respiratory infections.

• Advise avoiding trigger foods (often acidic foods).

Mucosal Protectants

Mucosal protectants reduce gastric acid production and pepsin activity to protect the mucosa

• Pepsin is a gastric enzyme that breaks down proteins and may cause damage to the stomach lining

• Prototype: Sucralfate

Sucralfate

A mucosal protectant drug

• MoA: Locally reacts with HCl and pepsin in the stomach to form a protective barrier that acts as an acid buffer

  • Forms a protective barrier over ulcers

  • Adheres to ulcers for up to 6 hours

• Indications: Short term treatment for duodenal ulcers, aspirin-induced ulcers, and chemotherapy-induced mucositis

• Contraindications: Chronic kidney failure, hypersensitivity

• Interactions: Cimetidine, Digoxin, Tetracycline

• Available as tablets and liquid suspension

• Should be taken on an empty stomach

Adverse Effects of Sucralfate

• diarrhea

• nausea

• dizziness

• insomnia

• dry mouth

• hyperglycemia

• itchy skin / rash

Nursing Considerations for Sucralfate

• Educate the client regarding short-term duration of use for these medications, typically 4–8 weeks.

• Inform clients of childbearing age about the potential risk to the fetus, which could result in a miscarriage

• Should be taken at least 2 hours before or after medications

• Should be taken on an empty stomach

Weight Management Drugs

• Anorexiants

• Glucagon-Like Peptide-1 (GLP-1) Receptor Agonists

• Bupropion Naltrexone (other category)

BMI

• Healthy weight: 18.5–24.9 kg/m²

• Overweight: 25.0–29.9 kg/m²

• Obese: 30.0+ kg/m²

Anorexiants

Anorexiants are drugs used to promote weight loss through appetite suppression and metabolism stimulation

• These drugs work by increasing norepinephrine availability to neural receptors

• Many have been removed from the market due to critical and fatal effects of body stimulation

• Prototype: Phentermine

Phentermine

Anorexiant

• MoA: Causes CNS stimulation, specifically the release of norepinephrine from the hypothalamus, which suppresses the appetite while increasing the basal metabolic rate, resulting in weight loss

• Indication: Adults with obesity, for overweight adults with comorbidities, children age 12+ with BMI in 95th percentile

• Contraindications: concurrent use with MAOIs, history of cardiovascular disease, hyperthyroidism, glaucoma, hypertension

• Interactions: MAOIs

Adverse Effects of Phentermine

• palpitations

• tachycardia

• restlessness

• dizziness

• insomnia

• dry mouth

• constipation

• severe side effects include pulmonary hypertension, cardiovascular risks, and dependency risks

Nursing Considerations for Phentermine

• Assess cardiovascular status frequently

• Monitor weight at least three times per week

• Monitor for potential misuse and dependency

• Avoid nighttime doses

• Do not crush extended-release capsules

GLP-1 Receptor Agonists

Were originally developed for diabetes but also promote weight loss.

• They suppress appetite and delay gastric emptying.

• Prototype: Semaglutide (Wegovy)

Semaglutide

GLP-1 Receptor Agonist

• MoA: Stimulates insulin release in the body while decreasing the release of glucagon, delaying gastric emptying and lowering glucose levels

• Indication: Adjunct therapy in weight management for adults with obesity or overweight with at least one comorbidity

• Contraindications: personal/family history of medullary thyroid carcinoma, pregnancy, lactation

• Interactions: Sulfonylureas, Insulin, alcohol

Adverse Effects of Semaglutide

• nausea

• vomiting

• diarrhea

• abdominal pain

• tachycardia/palpitations

• Severe risks: pancreatitis, gallbladder disease, hypoglycemia

Nursing Considerations for Semaglutide

• Monitor weight, blood pressure, and lab values.

• Assess for signs of hypoglycemia.

• Educate clients on drug interactions and potential adverse effects.

• Provide guidance on lifestyle changes like diet and exercise

• Rotate SQ injection sites

• Avoid alcohol

Bupropion Naltrexone

Weight Management Drug

• MoA: Stimulates and inhibits various pathways of the CNS, resulting in weight reduction and maintenance of weight loss

• Indications: weight loss and maintenance

• Contraindications: Uncontrolled hypertension, Seizure disorder, Anorexia nervosa or bulimia

• Interactions: MAOIs, Digoxin

Adverse Effects of Bupropion Naltrexone

• Nausea/vomiting

• Constipation/diarrhea

• Headache

• Dizziness

• Insomnia

• Dry mouth

Nursing Considerations for Bupropion Naltrexone

• Monitor the client’s weight, blood pressure, and lab values

• Monitor clients with hypertension closely

• Monitor client’s weight every 3 months for dosage changes as needed.

• Monitor for worsening signs of depression or suicidal ideation that may occur with some weight-loss supplements