OIA2004 PHARMACOTHERAPY OF NAUSEA & VOMITING

Nausea

An unpleasant, painless sensation that one may potentially vomit, often accompanied by pallor, tachycardia, and diaphoresis.

Retching

Rhythmic contractions of the abdominal wall, diaphragm, and thoracic muscles without expulsion of gastric contents.

Vomiting (Emesis)

A forceful expulsion of gastric contents through the mouth as part of an autonomic response.

Vomiting Center

Located in the medulla oblongata, coordinating the vomiting reflex.

Chemoreceptor Trigger Zone (CTZ)

Located in the area postrema, responds to toxins, drugs, and metabolic disturbances.

Vestibular System

Involved in motion sickness; contains histamine (H1) and muscarinic (M1) receptors.

Gastrointestinal Tract and Vagus Nerve

The vagus nerve transmits signals from the GIT to the brain via 5-HT3 receptors.

Higher Brain Centers

Psychological factors such as stress, fear, and anxiety can contribute to nausea.

Gastrointestinal Disorders

Gastroenteritis, gastritis, peptic ulcer disease (PUD).

Motion Sickness

Due to overstimulation of the vestibular system.

Pregnancy (Morning Sickness)

Associated with hormonal changes, mainly hCG.

Postoperative Nausea and Vomiting (PONV)

Common after anesthesia and surgery.

Chemotherapy-Induced Nausea and Vomiting (CINV)

Triggered by chemotherapeutic agents stimulating the CTZ.

Metabolic Causes

Diabetic ketoacidosis (DKA), Addison’s disease, uremia.

Psychogenic Factors

Anxiety, eating disorders.

Serotonin (5-HT3)

Plays a key role in CINV, PONV, and GIT-related nausea.

Dopamine (D2 Receptors)

Located in the CTZ, involved in drug-induced nausea.

Histamine (H1 Receptors)

Involved in motion sickness and vestibular disturbances.

Acetylcholine (M1 Receptors)

Found in the vestibular system, associated with motion sickness.

Substance P (NK1 Receptors)

Plays a role in delayed-phase CINV.

5-HT3 Receptor Antagonists

Ondansetron, granisetron, palonosetron

Used for CINV, PONV, and radiation-induced nausea.

Dopamine Antagonists

Metoclopramide, domperidone, prochlorperazine

Used for drug-induced nausea, gastroparesis.

Histamine (H1) Antagonists

Dimenhydrinate, meclizine, promethazine

Effective for motion sickness.

Muscarinic (M1) Antagonists

Scopolamine

Used for motion sickness and PONV.

Neurokinin-1 (NK1) Receptor Antagonists

Aprepitant, fosaprepitant

Effective in delayed CINV.

Corticosteroids

Dexamethasone

Used for CINV and PONV.

Benzodiazepines

Lorazepam, diazepam

Used in anticipatory nausea.

Cannabinoids

Dronabinol, nabilone

Used in CINV, particularly for refractory cases.

Prokinetic Agents

Metoclopramide

Increases gastric emptying, useful in gastroparesis.

Dietary Changes

Small, frequent meals, avoiding spicy or fatty foods.

Relaxation Techniques

Breathing exercises, meditation, progressive muscle relaxation.

Hypnosis

Used in psychogenic vomiting and anticipatory nausea.

Music Therapy

Shown to reduce nausea in chemotherapy patients.

Acupuncture and Acupressure

P6 (Neiguan) point stimulation for nausea relief.

Severity of Nausea

Assessed using patient-reported scales.

Number of Vomiting Episodes

Monitoring frequency before and after treatment.

Volume of Vomitus

Evaluating dehydration risk.

Acid-Base and Electrolyte Status

Hypokalemia and metabolic alkalosis common in severe vomiting.

Mucous Membrane and Skin Turgor

Assessing hydration status.

Prevention of Complications

Avoiding aspiration pneumonia, dehydration, and nutritional deficiencies.