| drug | mechanism | comments | side effcts |
| ttt of peptic ulcer | |||
| A) drugs decrease secreation of acid | |||
| omeprozole *** | 1-{proton pump inhibitors} selective inhibition of enz H/K ATPase in gastric parietal cells > ! Exchange mech of protons for K | *prodrug >needs activation in acid med (3-4) & degradation at low (1) so it is present as enteric coated capsules *abs >small intestine | 1-headache 2-diarrhea constipation 3-skin rashes |
| Pantoprazole sodium *** | any secretory drug in chronic use > + risk of gastric tomours (20mg capsule) | ||
| 2-H2 blockers | eg cimitidine ,Ranitidine ,nizatidine ,farmotidine | related to cimitidine | |
| Pirenzipine *** | inhibit sec of acid | used now in low doses that do not affect other organs | dry mouth ,constipation ,blurred vision |
| B) antacids (neutralization of secreated acid) | |||
| Antacids weak bases react e gastric HCL > salt & water | 1-neutralization of sec acid 2-inhibition of pepsin (inactive in PH 4) | bases of (oH ,trisilicate ,Co3 ,Hco3) metal ions (Mg ,AL ,Na) *salts of Bi & Ca rarely used due to high toxicity | *Mg salts > diarrhea *Al salts 1-constipation 2-drug adsorption eg CPZ ,thyroxine ,tetracycline 3-hypophosphatemia *Na salts (Na2Co3 ,NaHCo3) >systemic alkalosis may cause acid rebound effect >evolution of Co2 >w stim sec of HCl |
| C) drugs that increase mucosal resistance | |||
| 1- sucralfate (basic aluminium sucrose sulphate) (sulphated disacch) | 1- + sec of Hco3 & mucous in intestine 2-acts as a barrier () necrotic ulcer tissue & luminal acid 3-+ syn of endogenous PG (PGA!) > + mucous formation | *it is prodrug needs activation in acid medium ,should be used 1hr before meals *inactivated at PH (4-5) high PH so contraindicated e antacid | |
| 2- synthetic liqurice derivatives eg Carbenoxolone | 1-+ production ,secretion & viscosity of mucous 2-inhibit diffusion of luminal acid to mucosal cells | used in healing of peptic & duodenal ulcers | sodium retention >oedema & hypertension |
| 3-Misoprostol ** | 1-inhibit diffusion of luminal acid into mucosal cells 2-inhibit sec of gasric acid 3-stim production of mucous & bicarbonate | it is syn analogue of PGE1 *used esp in patients taking high doses of NSAID | 1-headache 2-flushing 3-dysmenorrhea in females |
| ttt of vomiting | |||
| 1-Metoclopramide | 1- central block of Dopamine D2-Rs (anti emetic effect) 2- it has have prokinetic effect > + motility of GIT > + emptying of stomach due t + activity of ach at muscarinic Rs in GIT | used in postoperative vomiting due to general anaesthesia & nausea ,vomiting of pregnancy | the same but more in metoclopramide 1-extrapyramidal dystonia (facial spasms ,oculogenic crisis due to over stim of muscarinic Rs esp in children & in patients taking phenodiazine drug *ttt by IV antimuscarinic drugs eg benzotropine 2-Gynacosmastia & galactoria due to + sec of prolactin hor |
| 2-Domperidone | 1- central block of Dopamine D2-Rs (anti emetic effect) 2- it has have prokinetic effect due to blocking of a- adrenoceptors in GIT > ! Relaxation effect > + motility | postoperative nausea & vomiting & in ttt of GER (gastroeosophagyl reflex) due to its prokinetic action (الارتجاع المعدي) | |
| 3-Ondansetrone *** | blocker of SHT3 Rs | used in prevent nausea & vomiting so used in chemotherapy & radiotherapy of cancer | headache |
| 4-H1 blockers | anti motion sickness (eg Dimenhydrinate ,promethazine ,cyclizine ) | ||
| Hyoscine | |||