Saturday 6 May 2017

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 ยต 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.



CTZ pathway, NTS pathway, vomiting center pathway, vomiting induce medicine, vomiting induce pathway. apomorphin mode of action, mechanism of action of emetic, mechanism of action of ipecaunha

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