Pharmacology

Drug resistance:

The mechanism of chemotherapy resistance and example

p/s: snap capture of pharmacology revision notes 


Methods to overcome drug resistance-
Intensifying dose ,Combining non - cross resistant drugs and Gene therapy.


Example of pharmacology BOF

Which of the following is true regarding Irinotecan
A.  Is a Topoisomerase II inhibitor
B.  Is a prodrug that activated by hydrolase
C.  diarrhoea mediated by acute cholinergic effect only
D.  Chronic dirrhoea treated with IV atropine
E.  Expression P170 by MDR gene leads to drug resistance





Answer: E
Irinotecan  stabilize  this  (topoisomerase-1  &  DNA  complex)  and  prevent  religation  that leads to collision of complex and advancing replicating fork→ DNA break.It’s a prodrug activated  by carboxylesterase  to  SN-  38.Acute  diarrhea  mediated  by  acute  cholinergic effect  and  treated  and  prevented  by  IV  atropine  which  occurred  <24  hour after the Irinotecan given. Delayed diarrhoea caused by SN-38 that irriated the intestinal mucosal and  treated  with  Tablet  Loperamide  around  the  clock  and  considers  antibiotic metronidazole for colitis dirrhea persistent .