Emetics

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Content

•Emesis

•Regurgitation, Rumination and Bulimia

•Pathophysiology of emesis

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Objectives

At the end of this lecture, student will be able to

• Explain the difference between Regurgitation, Rumination

and Bulimia

• Describe the pathophysiology of vomiting

• Explain about emetics

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Vomiting

• Vomiting is often preceded by nausea and may be accompanied by

retching

• Vomiting can be a valuable physiological response to the ingestion

of a toxic substance such as alcohol

• It is also an unwanted side effect of many clinically used drugs,

mainly cancer chemotherapy, opioids, general anesthetics.

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It is important to differentiate vomiting from Regurgitation, Rumination
and Bulimia.

Regurgitation Rumination Bulimia

• It is the return • It is the passive • It involves over
of esophageal or regurgitation of eating followed
gastric contents recently by self-induced
into the hypo ingested food vomiting.
pharynx with into the mouth
little effort. followed by

rechewing,
reswallowing or
spitting out.

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Pathophysiology

• Complex interactions between central and peripheral pathways.

• The most imp areas involved peripherally are the gastric mucosa

and smooth muscle (the enteric brain) and the afferent pathways of

the vagus and sympathetic nerves.

• The significant areas involved centrally are the area postrema, the

Chemo receptor Trigger zone (CTZ), the nucleus tractus solitarus

(NTS) and the vomiting centre.

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Pathophysiology cont..

From pharmacotherapeutic point of view, the most imp aspect of this

complex pathophysiology is the variety of receptors involved including:

▪ Histaminergic (H1)

▪ Cholinergic (Muscarinic M1)

▪ Dopaminergic (D2)

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Pathophysiology cont..

▪ Serotonergic (5HT3)

▪ Neurokinin-1 (NK1) receptors

In the clinical situation, this becomes target for various drugs

directed at controlling the symptoms.

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Emetics

• The most commonly used emetics are Ipecac and Apomorphine.

• Induced emesis is the preferred means of emptying the stomach in

awake patients who have ingested a toxic substance or have

recently taken a drug overdose.

• Vomiting blood is often caused by ulcers, ruptured blood vessels,

and stomach bleeding. It can also be caused by some forms of

cancer

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Emetics cont..

• Emesis should not be induced if patient has CNS depression or has

ingested certain volatile hydrocarbons or caustic substances

• Frequent vomiting not related to any of these causes may be a

symptom of cyclic vomiting syndrome.

• This condition is characterized by vomiting for up to 10 days.

• It is usually coupled with nausea and extreme lack of energy. It

mainly occurs during childhood

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Emetics cont..

• Ipecac syrup(15-30 ml in adults, 10-15 ml in children, 5 ml in infants)

is prepared from the dried rhizome and roots of Cephaelis

ipecacuanha or Cephaelis acuminata, plants from Brazil and Central

America

• Ipecac – stimulates the CTZ in the medulla & acts directly on the

gastric mucosa – take w/ water (not milk or carbonation)

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• Onset in 15 to 30 min.

• Toxic if absorbed → give charcoal.

• S/E: Hypotension, tachycardia, chest pain ,diarrhea, sedation,

lethargy

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Emetics cont..

• Have alkaloid emetine as active principal ingredient

• Acts directly on CTZ and indirectly by irritating gastric mucosa

• The chemoreceptor trigger zone at the base of the fourth ventricle

has numerous dopamine receptors

• Serotonin 5-HT3 receptors,opioid receptors acetylcholine receptors

and receptors for substance P

• Stimulation of different receptors are involved in different pathways

leading to emesis, in the final common pathway substance P

appears involved

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Emetics cont..

• It is cardio toxic if absorbed and causes cardiac conduction

disturbances, atrial fibrilation, or fatal myocarditis

• If emesis does not occur, gastric lavage using a nasogastric tube

must be performed

• Dehydration is the most common complication related to vomiting.

Vomiting causes your stomach to expel not only food but fluids

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Emetics cont..
• It should be available in every household for emergency use.

• Less dependable than parenteral apomorphine

• Takes 15 min or more for its effect, but is safer

• The vagal and enteric nervous system inputs transmit information

regarding the state of the gastrointestinal system.

• Irritation of the GI mucosa by chemotherapy, radiation, distention,

or acute infectious gastroenteritis activates the 5-HT3 receptors of

these inputs.

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Emetics cont..

• Apomorphine, a derivative of morphine, acts as dopaminergic agonist

directly on CTZ.

• Injected i.m./s.c. In a dose of 6 mg, induces vomiting within 5 min.

• Oral use not recommended as emetic dose is larger.

• The CNS mediates vomiting that arises from psychiatric disorders and

stress from higher brain centers

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Emetics cont..

• More effective if water is first administered before oral or s.c.

dosing.

• Excessive dosage may cause respiratory depression and circulatory

collapse.

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Emetics cont..

• Opioid antagonists (naloxone) usually reverse the depressant

actions of apomorphine.

• Not frequently used as emetic.

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Summary
• Vomiting is a complex reflex activity.

• Emetic drug or vomiting drug are those drug which is responsible

for the vomiting.

• Emetic drug is apply when an undesirable like poison has been

injected.

• When an individual has consumed certain toxic substances and

must be expelled before absorption

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Thank You
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