Emetic and its drug

Emetics

Emetics are agents that induce and produce the vomiting by stimulation of vomiting center present in medulla oblongata. Those agents are mainly used in poison case and taken orally over dose. 

Pathogenesis of Vomiting Occurring / How to produce emesis or Vomiting

Multiple pathways are involved in induce vomiting.

Vomiting center is present in medulla oblongata that received the impulse and induces vomiting.

Chemoreceptor trigger zone (CTZ) and Nucleus tractus solitarius (NTS) are send the impulse to Vomiting Center for cause vomiting.

Vomiting center is received impulse in various way, these are follows:

                                                                                                              

1)    Chemoreceptor trigger zone: 

  CTZ is located in the area postrema near to vomiting center in medulla oblongata. CTZ is outside of blood brain barrier. Many poisons and drugs are present in blood, which can entered CTZ and stimulated it (CTZ). That can generate the impulse and send to the vomiting center and vomiting induces. Chemo word comes from chemotherapy, which mainly induces vomiting due to chemotherapy.  CTZ express various receptors eg. Dopamine D₂ receptor, Histamine H₁ receptor, serotonin 5-HT3 receptor, opioid µ receptor and cholinergic M receptor. 

2)   Nucleus Tractus Solitarius (NTS): 

   NTS received the impulse from gastrointestinal tract (GIT), throat and other viscera. NTS send to impulse vomiting center and induce vomiting. NTS is located near vomiting center in medulla oblongata. NTS express a variety of receptor such as: serotonin 5-HT3 receptor, dopamine D₂ receptor, cholinergic M receptor and histamine H₁ receptor.

3)   Vestibular Apparatus: 

   Vestibular apparatus generate impulse when equilibrium imbalance or body rotate or balance disturb. Than these impulse which generated in the vestibular apparatus send to the vomiting center and vomiting induce. Cause vomiting due to motion sickness.

4)   Cerebral Cortex: 

  Cerebral cortex can induce vomiting due to pain, bad smell/odor, sight, psychogenic stimuli. Cerebral cortex is higher center to direct simulate the vomiting center and cause vomiting.

Pathagenosis Of emetic or mode of vomiting/ emesis/ emetic or pathway of emetic/vomiting or vomiting produce pathway or signaling pathway for causing vomiting 

Emetic Drugs

1)   Apomorphine

2)   Ipecacuanha 

Apomorphine

Apomorphine is a derivative of morphine which acts as dopamine D₂ agonist on the CTZ. Oral dose of apomorphine cannot produce any action.  It produced response by taking intramuscular or subcutaneous route.

Apomorphine Contraindicated

1)   Unconscious patient

2)   Respiration depressant

3)   CNS stimulant drug poising

4)   Corrosive (acid , alkali) poising

Ipecacuanha

Ipecacuanha is source of dried root of “Cephaelis ipecacuanha”. It contains the emetins that used as emetic agents. It produces action by irritating gastric mucosa and also by CTZ. 

Contraindicated

1)   Corrosive (acid, alkali) poisoning
2) Unconscious patient