Introduction
Emetics: Drugs that induce vomiting and used in poisoning cases to empty stomach (rarely used now)
Antiemetics: Drugs that prevent or relieve vomiting
List of Emetic Drugs
1. Central acting:
Eg. Apomorphine
2. Peripheral acting:
Eg. Ipecac syrup
Apomorphine
MOA: Direct dopamine agonist on CTZ (central action)
Therapeutic Use: Rarely used to induce vomiting in poisoning (under medical supervision)
Adverse Effects:
•
Respiratory depression
•
Hypotension
•
Sedation
• Contraindicated in CNS depressant
poisoning
Ipecac Syrup
MOA:
• Irritates gastric mucosa (peripheral
action)
•
Stimulates CTZ (central action)
Therapeutic Use:
•
Previously used to induce vomiting in
poisoning
Adverse Effects:
•
Prolonged vomiting
•
Diarrhea
•
Aspiration pneumonia
•
Cardiotoxicity with repeated use
Classification of Antiemetics
1. Anticholinergics
– Hyoscine, Dicyclomine
2. H1 Antihistaminics
– Promethazine, Cinnarizine, Diphenhydramine
3. Neuroleptics (D2 antagonists)
– Chlorpromazine, Prochlorperazine, Haloperidol
4. Prokinetic agents – Metoclopramide,
Domperidone
5. 5-HT3 antagonists – Ondansetron,
Granisetron
6. NK1 antagonists – Aprepitant
7. Cannabinoids – Dronabinol
1. Anticholinergics: Hyoscine, Dicyclomine
Anticholinergics – Mechanism of Action
- Hyoscine & Dicyclomine: Muscarinic (M1/M3)
receptor antagonists
- ↓ GI motility and spasms
- ↓ Vestibular input to
vomiting center (Hyoscine)
Anticholinergics – Uses & Adverse Effects
Therapeutic
Uses:
- Motion sickness (Hyoscine)
- IBS, abdominal cramps
(Dicyclomine)
Adverse
Effects:
- Dry mouth, blurred vision,
constipation, urinary retention
- CNS effects (drowsiness,
confusion)
Drug
Interactions:
- Additive with other
anticholinergics
- May oppose cholinergic
agents (e.g., neostigmine)
2. H1 Antihistaminics: Promethazine, Cinnarizine,
Diphenhydramine
H1 Antihistamines – MOA
- Block H1 receptors in CTZ
& vestibular nuclei
- Anticholinergic and sedative
properties
- Effective in motion
sickness, nausea
H1 Antihistamines – Uses & Adverse Effects
Uses:
- Motion sickness
(Cinnarizine, Diphenhydramine)
- Nausea, vomiting, allergy,
sedation (Promethazine)
Adverse
Effects:
- Sedation, dizziness, dry
mouth, blurred vision
Drug
Interactions:
- CNS depression ↑ with
alcohol, sedatives
- Additive anticholinergic
effects
3. Neuroleptics: Chlorpromazine, Prochlorperazine,
Haloperidol
Neuroleptics – MOA
- D2 dopamine receptor
antagonists in CTZ
- Also have anticholinergic
& antihistaminic action
Neuroleptics – Uses & Adverse Effects
Uses:
- Nausea & vomiting (esp.
drug-induced)
- Psychosis (Chlorpromazine,
Haloperidol)
Adverse
Effects:
- Extrapyramidal symptoms
(EPS)
- Sedation, hypotension,
anticholinergic effects
Drug
Interactions:
- Additive CNS depression
- Interaction with
anticholinergics, Parkinson drugs
4. Prokinetic Drugs: Metoclopramide, Domperidone
Prokinetics – MOA
- Metoclopramide: D2 antagonist + 5-HT4
agonist
- Domperidone: Peripheral D2 antagonist
- ↑ GI motility, tone of LES,
gastric emptying
- Block CTZ (antiemetic)
Prokinetics – Uses, AE & Interactions
Uses:
- Gastroparesis, GERD,
nausea/vomiting
Adverse
Effects:
- Metoclopramide: EPS,
sedation, galactorrhea
- Domperidone: Less CNS
effect, QT prolongation
Drug
Interactions:
- ↑ EPS risk with
antipsychotics
- ↓ action with
anticholinergics
- QT prolongation with macrolides, fluoroquinolones
5. 5-HT3 Antagonists: Ondansetron, Granisetron
5-HT3 Antagonists – MOA
- Block 5-HT3 receptors in GI
tract & CTZ
- Inhibit serotonin-mediated
emesis (e.g., chemotherapy)
Uses:
- Chemotherapy-induced
nausea/vomiting
- Post-operative &
radiation-induced emesis
Adverse
Effects:
- Headache, constipation, QT
prolongation
Drug
Interactions:
- ↑ QT prolongation with other
cardiotoxic drugs
- Caution with serotonergic
agents (serotonin syndrome)
6. Antispasmodics: Dicyclomine, Drotaverine,
Hyoscine Butylbromide
Antispasmodics – MOA
- Dicyclomine, Hyoscine
butylbromide:
Anticholinergic → ↓ GI smooth muscle spasms
- Drotaverine: PDE4 inhibitor → ↑ cAMP →
smooth muscle relaxation
Uses:
- IBS, abdominal cramps,
biliary/renal colic
Adverse
Effects:
- Anticholinergic (dry mouth,
blurred vision)
- Drotaverine: hypotension,
vertigo
Drug
Interactions:
- Anticholinergics → additive
CNS/GI effects
- Drotaverine may potentiate
antihypertensives
References & Further Reading
- Goodman & Gilman’s
Pharmacological Basis of Therapeutics
- Katzung’s Basic &
Clinical Pharmacology
- National Formulary of India
(NFI)
- Clinical guidelines on
antiemetics (e.g., ASCO, WHO)
END OF THE DOCUMENT
Hi. I’m Writer of Researchsop.com. ’ ’ Please share these SOPs to all concern pharma people for their development. I like to fullfill the need of curious people. These things inspire me to make things looks better.
0 comments:
Post a Comment