GI 06: Therapeutics of Nausea Vomitting

💡 1. Goals of Therapy

1⃣ Prevent or eliminate N&V – ideally stop nausea before vomiting starts.
2⃣ Reduce severity, frequency, and duration if complete prevention isn’t possible.
3⃣ Identify and treat underlying causes (e.g., infection, medications, metabolic issues).
4⃣ Correct complications – dehydration, electrolyte imbalance, nutritional deficiencies.
5⃣ Prevent recurrence – e.g., for chemo or post-op patients, use prophylaxis.
6⃣ Prevent complications – aspiration, esophageal tears, wound dehiscence, etc.
7⃣ Minimize impact on daily life – keep patients eating, hydrated, working.
8⃣ Minimize medication side effects – choose safest options, avoid polypharmacy

.

🤢 2. Common Signs & Symptoms

• Core symptoms: nausea, vomiting, retching

• Associated:

  • ↑ salivation, yawning, abdominal discomfort

  • Pallor / cold sweats

  • Rapid, shallow breathing

  • Dizziness, headache, drowsiness

  • Restlessness, difficulty concentrating

🧠 3. Common Causes of Nausea & Vomiting

A. Central Nervous System Causes

• Head trauma, ↑ ICP, meningitis, stroke, brain mets

• Seizures, migraine

• Psychological: fear, anxiety, grief, pain, eating disorders, anticipatory nausea

B. Cardiovascular

• MI, CHF

C. Vestibular Apparatus (Inner Ear)

• Motion sickness, Meniere’s disease, cerebellar tumor

D. Gastrointestinal

• Gastric irritation (alcohol, blood, stress, radiation)

• Obstruction, constipation

• Cholecystitis/cholangitis

• Viral gastroenteritis

• Gastroparesis, GERD

• Appendicitis, pancreatitis, hepatitis, IBS

E. Metabolic & Other Medical

• Infections (UTI, otitis media, pyelonephritis)

• DKA, Addison’s disease, renal failure (uremia)

• Hypercalcemia, hypernatremia, hypothyroidism

• Pregnancy, malignancy, operative procedures, toxins (food, drugs)

💊 4. Medications that Can Cause or Worsen N&V

Anti-inflammatories: ASA, NSAIDs, corticosteroids, colchicine
Anti-infectives: tetracyclines, macrolides (esp. erythromycin), metronidazole, amphotericin
Anticonvulsants: carbamazepine, valproic acid, phenytoin
Antineoplastics: many
Cardiovascular: β-blockers, calcium channel blockers, digoxin, amiodarone
CNS agents: opioids, antidepressants, antipsychotics
Metabolic: metformin, sulfonylureas, iron, bisphosphonates, theophylline, levodopa
Others: oral contraceptives, alcohol, cannabis, nicotine

⚠ 5. Consequences of Persistent N&V

• Fluid & electrolyte loss → dehydration, hypovolemia, arrhythmias

• Nutritional deficits → weight loss, malnutrition

• Physical injury → aspiration, intestinal/esophageal tears

• Oral damage → dental caries

• Behavioural → anticipatory nausea/vomiting

• Medication issues → non-adherence

• Health system impact → longer hospital stays, higher nursing workload

• Emotional avoidance: fear of future procedures

💧 6. Assessing Dehydration / Hypovolemia

All patients:
↑ HR/RR, dizziness, confusion, dry mucous membranes, thirst, ↓ urination, ↓ skin turgor, cramps, weakness.
Infants/children:
Sunken fontanelle, no tears, < 4 wet diapers/24 h, pale skin, ↓ weight

.

🚫 7. Contraindications by Drug Class

🍎 8. Non-Drug Measures (for all patients)

• Maintain hydration (1–3 L water/day in adults)
  → take small, frequent sips instead of large volumes.

• Replace electrolytes (Na⁺/K⁺): diluted juice, ORS (Pedialyte®, Hydralyte®, Gatorade® diluted).

• Avoid spicy, fatty, or strong-smelling foods.

• Eat small, bland meals; avoid lying flat after eating.

• Wear loose clothes; get fresh air; rest.

• Treat triggers (pain, reflux, constipation).

• Caution: juices with high sugar may worsen diarrhea, esp. in elderly, young, or diabetic patients

  .

🩺 9. Monitoring Plan (General)

Efficacy:

• ↓ nausea/vomiting frequency

• Improved oral intake

• Stable weight

• Improved hydration signs

• Normal mental status

Safety:

• Monitor for sedation, constipation, QT prolongation, EPS, anticholinergic effects, or serotonin syndrome depending on drug used.

• If ADRs occur → lower dose, switch agent, or emphasize non-drug measures

  .

🧭 10. Pharmacist’s Approach to a Patient with N&V

1⃣ Rule out red flags → persistent (> 3 days adults / > 6 h child), blood in vomit, dehydration, altered LOC, trauma, etc.
2⃣ Identify cause & pathway (GI, vestibular, CTZ, cortical).
3⃣ Identify neurotransmitters involved (dopamine, serotonin, acetylcholine, histamine, substance P, vasopressin).
4⃣ Select an agent that blocks those transmitters.
5⃣ Tailor to patient: route, past response, cost, safety.
6⃣ Combine with non-drug care

💫 Part 2 — Types of Nausea & Vomiting

🚗 1. Motion Sickness

🧠 Pathophysiology

• Caused by a mismatch between what your eyes see and what your vestibular (inner-ear balance) system senses.

• “Normal response to abnormal perception of motion.”

• Can occur while moving (e.g., car, boat, plane) or while stationary but viewing motion (e.g., movies, VR).

• Involves vestibular apparatus → cerebellum → vomiting centre.

• Key neurotransmitters: acetylcholine and histamine

👩‍⚕ Risk Factors

• Female > Male

• Children 3–12 years old

• Migraines

• Poor ventilation / strong odors

• Emotional stress

• Pregnancy or hormonal therapy

• Rare < 2 yrs; uncommon > 50 yrs

💊 Pharmacologic Treatment

👉 Prevention is more effective than treatment! Take 30–60 min before travel.

(Meclizine compound available in some pharmacies; not commercial in Canada.)

🌿 Non-Drug Measures

• Avoid large meals within 3 h of travel.

• Avoid dairy, salty, greasy, or high-protein meals.

• During travel: no alcohol, smoking, reading, or screen time.

• Sit facing forward; best spots = front seat of car, middle of boat, by wing on plane.

• Look at horizon / stable object; open windows for fresh air.

• Lie semi-reclined if possible

🧘‍♀ Natural / Complementary Remedies

• Ginger (tea, capsules, powder) – mild benefit.

• Peppermint tea or mints.

• Acupressure (P6 / “Nei Guan” wrist point): limited evidence; may cause mild discomfort.

• Aromatherapy with isopropyl alcohol = not better than placebo

💊 2. Opioid-Induced Nausea & Vomiting (OINV)

📊 Overview

• Occurs in up to 70 % of patients starting opioids — especially opioid-naïve or on high doses.

• Usually appears early and tolerance develops in a few days.

• Caused by direct stimulation of CTZ, vestibular apparatus, and cerebral cortex.

• Not specific to one opioid — all can cause it

🩹 Non-Drug Measures

• Use lowest effective dose, avoid rapid dose increases.

• Ensure pain is adequately managed (uncontrolled pain itself worsens nausea).

• Consider adding non-opioid analgesics to reduce total opioid dose.

• Try switching opioids (start at 75 % of equianalgesic dose).

• Change route (SL, IV, SC) if oral not tolerated

💊 Pharmacologic Options

Pick based on patient tolerance & contraindications.

🧾 Counseling & Monitoring

• Start at low dose; report dizziness, tremor, palpitations, or EPS symptoms.

• Avoid alcohol or driving until response known.

• Expect tolerance to develop within days.

• Reassess pain and hydration frequently.

🏥 3. Post-Operative Nausea & Vomiting (PONV)

📖 Definition

• Nausea/vomiting within 24 hours post-surgery.

• Incidence 20–30 %; up to 80 % in high-risk patients.

• Multifactorial: patient, surgical, anesthetic, and medication factors.

• Prevention is key!

⚠ Risk Factors

Patient-related:

• Female, nonsmoker, age < 50, prior PONV or motion sickness

Anesthetic-related:

• General > regional anesthesia

• Volatile anesthetics, nitrous oxide, long procedures

Surgery-related:

• Opioid use (intra-/post-op)

• Type: cholecystectomy, laparoscopy, gynecologic procedures

• In children: ≥ 3 yrs old, long surgery > 30 min, strabismus/tonsil surgery, FHx PONV

📊 Risk Scoring

Adults (Apfel Score)
Female + nonsmoker + Hx PONV/motion sickness + opioid use = 1 pt each
0 = 10 %, 1 = 20 %, 2 = 40 %, 3 = 60 %, 4 = 80 % risk

Children (POVOC Score)
≥ 30 min surgery, ≥ 3 yrs, strabismus/tonsil surgery, FHx PONV
0–1 pt = 10 %, 2 = 30 %, 3 = 50 %, 4 = 70 %

🧘‍♀ Baseline Risk Reduction

• Prefer regional anesthesia or TIVA (propofol) over inhaled agents.

• Avoid nitrous oxide if possible.

• Maintain adequate IV hydration.

• Limit perioperative opioids; use non-opioid analgesia when possible.

💊 Prophylactic Drug Therapy

Choose based on risk level:

• Low risk (0–1 factors): none or 1 agent

• Medium risk (1–2): 2 agents

• High risk (> 2): 3–4 interventions

💬 Ondansetron, dexamethasone, and haloperidol have comparable efficacy; combination therapy (e.g., ondansetron + dexamethasone) yields best results.

🚨 Rescue Treatment

• If prophylaxis fails → choose an agent from a different class.

• Re-dose same class only if > 6 h since prior dose.

• Do not repeat long-acting drugs (e.g., dexamethasone, palonosetron, aprepitant).

• If no prophylaxis given → start 5-HT₃ antagonist (ondansetron best studied)

🌿 Non-Drug Measures

• IV fluid optimization.

• P6 acupressure (RR ≈ 0.69).

• Ginger 1 g PO 1 h before anesthesia (↓ severity > placebo).

• Possibly chewing gum or isopropyl alcohol aromatherapy

🦠 4. Gastroenteritis

📋 Overview

• “Stomach flu”: acute inflammation of stomach and intestines.

• Viral causes: Norwalk, rotavirus, enteric adenovirus.

• Transmitted fecal-oral ± aerosol or contaminated surfaces.

• Self-limiting (1–3 days) but dangerous in young & elderly.

• Symptoms: sudden diarrhea ± vomiting, fever/chills, abdominal cramps, anorexia, malaise

💧 Non-Drug Measures

• Oral rehydration therapy (ORT) = mainstay.

  • Use Pedialyte®, Hydralyte®, or diluted sports drinks.

• Hand hygiene critical (prevents spread).

• Maintain gentle diet: bland foods, avoid dairy or fatty foods until better.

💊 Pharmacologic

• No single antiemetic proven superior.

• Antiemetics used only to facilitate rehydration if vomiting prevents fluid intake.

• First-line: Dimenhydrinate (esp. children)

🧾 Monitoring

• Track hydration status (urine output, mucous membranes).

• Watch for prolonged vomiting, blood in stool, or dehydration → refer.

🤰 5. Pregnancy-Induced Nausea & Vomiting (NVP)

(Note: not deeply covered in slide deck, but referenced in motion sickness/pregnancy discussions — key therapeutic principles below.)

🌼 Background

• Occurs in up to 80 % of pregnancies, typically 5–12 weeks gestation.

• Usually mild; severe form = hyperemesis gravidarum (dehydration, weight loss > 5 %).

• Etiology: hormonal (hCG, estrogen), delayed gastric emptying, psychological stress.

💊 Pharmacologic Management

🌿 Non-Drug

• Eat small, bland meals; avoid fatty/spicy food.

• Eat crackers before rising; maintain hydration.

• Avoid triggers (odors, stress); rest adequately.

💡 Monitoring & Counseling

• Track weight, hydration, urine ketones.

• Reassure safety of first-line meds.

• Avoid self-medication without provider input.

🌈 Quick Recap Table