Drugs used for Anti - Emetics 2024.pptx

Emesis, or vomiting, is a physiologic
response to the presence of irritating and
potentially harmful substances in the gut
or bloodstream.

Classification of emetics:
1.Centrally acting
2.Peripherally acting
3.Both

Apomorphine
Dose-6mg for adults
C/I: resp. is slow & laboured
S/E:
1.Drug is unstable
2.Effective in parenteral
3.May cause resp. dep.

PERIPHERALLY ACTING:
SODIUM CHLORIDE:
ON ORAL ADMINISTERED, IT
WITHDRAWS FLUID FROM THE CELLS
LINNING THE STOMACH CAUSES
IRRITATION WHICH LEADS TO REFLEX
EMESIS.
S/E: DEATH BUT RARE

BOTH CENTRALLY & PERIPHERALLY:
SYRUP OF IPECAC:
 Prepared from dried roots contain emetine
 Produce emesis by local irritation of GIT &
its effect on the CTZ
 Emetine evoke emesis in poisoning cases
Dose:30 ml in adults
15 ml in children
C/I: should not combine with charcoal
S/E: may cause cardiotoxicity

Contra indication for emetics:
1.Corrosive chemical poisoning
2.CNS stimulants toxicity
3.Kerosene poisoning
4.Unconcious pts.

Classification:
1.Muscarinic receptor antagonist
2.Dopamine receptor antagonist
3.5HT3 receptor antagonist
4.Histamine H1receptor antagonist
5.NK1 receptor antagonist
6.Miscellaneous drugs

Scopolamine:
Pharmacodynamics:
Blocks the central muscarinic
receptors in afferent pathways of vomiting
reflex.
Also antagonizes histamine and serotonin
Pharmacokinetics:
 Absorption: Well absorbed by all routes of
administration
 Protein binding: Reversibly bound to
plasma proteins
 Metabolism: In the liver
 Elimination: In urine

Posology:
0.3-0.6mg p.o. in adults 15 min.
before food
Uses:
Prevention of motion sickness
Prevention of nausea/vomiting
associated with anesthesia or opiate
analgesia
Side effects:
Dry mouth, sedation, blurred vision,
urine retention, dizziness

Dopamine receptor antagonist:
a) Non-selective D1&D2
Phenothazine:
Butyrophenone:
b) D2 antagonist

METOCLOPERAMIDE
Pharmacodynamics:
Blocks dopamine receptors in
chemoreceptor trigger zone of the CNS;
Enhances the response to
acetylcholine of tissue in upper GI tract
causing enhanced motility and accelerated
gastric emptying without stimulating
gastric, biliary, or pancreatic secretions

Pharmacokinetics:
 ABSORPTION: Well on oral & parenteral
 DISTRIBUTION: Crosses the placenta;
appears in breast milk
 Protein binding: 30%
 Half-life: 4-7 hours
 METABOLISM: liver
 ELIMINATION: Primarily as unchanged
drug in urine and feces

Contraindications:
Hypersensitivity to metoclopramide
or any component; GI obstruction,
perforation or hemorrhage,
pheochromocytoma, history of seizure
disorder
Posology:
 1-2 mg/kg 30 minutes before
chemotherapy
 Postoperative nausea and vomiting: I.M.:
10 mg near end of surgery; 20 mg doses
may be used

Therapeutic uses:
1. As an antiemetic
2. CIV
3. Accelerate gastric emptying
4. Facilitate intubation
5. GERD
6. Gastroparesis & upper GI motility
disorders
ADVERSE REACTIONS:
Drowsiness, extrapyramidal reactions,
diarrhoea, hyperprolactinamia, Na
retension

 Selective D2 receptive antagonist
 Does not cross BBB
 No EP reactions
 Also causes hyperprolactinaemia
 Enhances gastric motility
 ↑ gastric emptying
 Effective oral & parenteral

HISTAMINE (H1) RECEPTOR
ANTAGONIST
 Promethazine
 Cyclizine
 Meclizine
 Diphenhydramine
 Cinnarizine

PROMETHAZINE
Pharmacodynamics:
Competes with histamine for the H1-
receptor
Pharmacokinetics:
 Well absorbed on oral administered
 Duration: 2-6 hours
 Metabolism: In the liver
 Elimination: Principally as inactive
metabolites in urine and in feces
Dosage:
0.25-1 mg/kg 4-6 times/day.

Adverse reactions:
Postural Hypotension, Tachycardia,
Dizziness, Photosensitivity, Xerostomia,
Agranulocytosis
Therapeutic uses:
 Antiemetic;
 Motion Sickness;
 Sedative;
 Analgesic Adjuvant For Control Of
Postoperative Pain;
 Anesthetic Adjuvant

5HT3 RECEPTOR ANTAGONISTS
 ONDANSETRON
 GRANISETRON
 DOLASETRON
 PALANOSETRON
 TROPISETRON

ONDANSETRON:
Pharmacodynamics:
Selective 5-HT3-receptor antagonist, blocking
serotonin, both peripherally on vagal nerve
terminals and centrally in the chemoreceptor
trigger zone
Pharmacokinetics:
 Absorption: well on oral & parenteral
 Plasma protein binding: 70% to 76%
 Metabolism: Extensively by hydroxylation,
followed by glucuronide or sulfate conjugation
 Half-life: Children <15 years: 2-3 hours;
Adults: 4 hours
 Elimination: In urine and feces; <10% of
parent drug recovered unchanged in urine

Uses:
Refractory to other anti emetics.
Adverse reactions:
Headache, fever, constipation,
diarrhea, Dizziness, Abdominal cramps,
xerostomia
Dosage:
ondansetron- 0.15mg/kg b.w.

Neurokinin1 receptor antagonist
Aprepitant
Pharmacodynamics:
Aprepitant is an antiemetic which
acts as a substance P/neurokinin 1 (NK1)
receptor antagonist.

PHARMACOKINETICS:
 Absorption: Absorbed in the GI tract.
cmax -4 hr.
Bioavailability: About 60-65%.
 Distribution: Vd: About 70 L
 Metabolism: Undergoes extensive hepatic
metabolism via oxidation by cytochrome
P450 isoenzymes.
 Excretion: Primarily by liver.

Therapeutic uses:
In Prophylaxis of chemotherapy-
induced nausea and vomiting
In Prophylaxis of postoperative
nausea and vomiting
Adverse reactions:
Headache, dizziness, nausea,
vomiting, constipation, abdominal pain,
dyspepsia, diarrhoea, dehydration,
fatigue, cough, hypotension, hypertension,
angioedema.

cannabinoids
• Tetrahydrocannabinol
• Synthetic cannabinoids
• Nabilone
• levonantradol

NABILONE
Nabilone is a cannabinoid. It is an
analogue of dronabinol. Also known as
tetrahydrocannabinol or THC
Pharmaco-Kinetics
Absorption: Rapid
Serum half-life: 35 hours

Adverse reactions:
Dizziness, drowsiness, vertigo,
euphoria, clumsiness, Xerostomia,
Orthostatic hypotension, Ataxia,
depression, Blurred vision
Therapeutic Uses:
Treatment of nausea and vomiting
associated with cancer chemotherapy
Dosage:
1-2 mg twice daily, 1-3 hours before
chemotherapy is administered.
Maximum daily dose: 6 mg divided in 3
doses

PYRIDOXINE
Treatment of vomiting associated
with pregnancy, radiation sickness,
meniere’s disease

TYPES OF EMESIS
 MOTION SICKNESS
 MORNING SICKNESS
 CHEMOTHERAPY OR RADIATION INDUCED
NAUSEA & VOMTING
 POST OPERATIVE VOMITING
 VOMITING OF VARIED ORIGIN

MOTION SICKNESS:
Imbalance between sensory inputs
from non-vestibular proprioceptors &
vision as well as sensory outputs from
vestibular apparatus to cerebellum
 Scopolamine
 Diphenhydramine
 Cyclizine
 Meclizine
 Promethazine
 Cinnerzine

MORNING SICKNESS:
In the Ist trimester of pregnancy due
to the effect of increased oestrogen levels
on CTZ
Cyclizine
Meclizine
Pyridoxine
Doxylamine

POST OPERATIVE EMESIS:
30-40%---due to G.A.
60-80%---in gynaecological surgeries
5HT3 antagonists
Anti histaminics
Prokinetics with D2 antagonists
Butyrophenone antipsychotics

CHEMOTHERAPY OR RADIATION THERAPY
INDUSED NAUSEA & VOMITING:
Emesis due to Anti-carcinogenic drugs has
two phases
Acute phase-within 24hrs of starting of
chemotherapy
Delayed phase-b/w 24hrs to 5days of
therapy
5HT3 antagonists
Nk1 antagonists
Adjuvants

VOMITING OF VARIED ORIGIN:
Drug induced
Due to Increased intra cranial pressure
5HT3 antagonists
Glucocorticoids
Benzodiazepines
CB1 analogues

Drugs used for Anti - Emetics 2024.pptx

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