GI DRUGS Flashcards
What drugs reduce gastric acid secretion?
H2 RECEPTOR ANTAGONIST- cimetidine, ranitidine
PPI- omeprazole
What is the MOA of h2 receptor antagonists?
Bind histamine
Reduce HCl
What is the MOA of omeprazole?
Omeprazole irreversibly binds to H+/K+ atpase -SH group
no H+ into stomach lumen
so cannot combine with Cl- in stomach lumen
no HCl
What uptake transporters are used to deliver hydrophilic drugs into plasma membrane for efficient absorption?
PEPT1 TRANSPORTER
OCTN2 TRANSPORTER- cation
OATP2B1 TRANSPORTER- anion
What are the substrates of PEPT1?
peptide based substrates of peptide recognised by a peptide bond Enalapril Alpha methyl dopa phenylalanine Penicillin's Cephalosporins- cefadroxil
What are the substrates of OCTN2?
Quinidine Verapamil Valproic acid Alpha methyldopa phenylalanine Valacyclovir Imatinib
What are the substrates of OATP2B1?
Pravastatin
Rosuvastatin
Atorvastatin
Fexofenadine
Why are efflux transporters used?
Drugs can be actively effluxed/pumped back into gut lumen
What is the MOA of uptake transporters?
Drug diffuses into plasma membrane
Recognised by efflux transporter and binds
ATP hydrolysed to adp and pi
Energy released used to pump drug out of cell into gut lumen
Reduces drug absorption
What uptake transporters are used?
P-GLYCOPROTEIN
BCRP (breast cancer resistance protein in human intestine)
What are the substrates of P-glycoprotein?
HIV PI indavir Immunosuppressants: ciclosporin A, tacrolimus Antibiotics: erythromycin Cardiotonic: digoxin Verapamil Quinidine Imatinib
How can anticancer agents absorption be increased?
Give with PGP modulator
What are the consequences of increasing anti cancer agent absorption?
Increased toxic side effects
What type of drugs giving examples cannot be delivered orally and why?
Protein drugs Pepsin protease enzyme in stomach Digests protein Protein drugs will become inactivated Examples= insulin
What drugs are inactivated by the acidic environment of the stomach HCl?
Penicillin G
Erythromycin
