digestive system part 1
Secretion Decreased Achlorhydria, hypochlorhydria biliary secretory dysfunctionIncreased insufficiency of pancreatic enzymes ulcer disease, GERD
Absorption Decreased malabsorption Inflammation Gallstones biliary colic Mucosa associated limphoid tissue inflammatory bowel disease (IBD), gastroenteritis acute, chronic hepatitis, acute, chronic pancreatitis
PHARMACOLOGY OF THE GI TRACT I. DRUGS USED IN ACID-PEPTIC DISEASES II. DRUGS STIMULATING GI MOTILITY III. LAXATIVES IV. ANTIDIARRHEAL AGENTS V. DRUGS USED FOR THE TREATMENT OF PHARMACOLOGY OF THE GI TRACT 3 IRRITABLE BOWEL SYNDROME (IBS) VI. ANTIEMETIC AGENTS VII. DRUGS USED TO TREAT INFLAMMATORY BOWEL DISEASE S VIII. PANCREATIC ENZYME SUPPLEMENTATION IX. BILE ACID THERAPY, TREATMENT OF HEPATITIS B and C, PBC, AACH X. DRUGS USED TO TREAT COMPLICATIONS OF CIRRHOSIS
I. DRUGS USED IN ACID-PEPTIC DISEASES
1 Sodium bicarbonate (baking soda)formation of CO2 + NaCl highly soluable in water
Co2 tension, post-acid production, sodium intake
I DRUGS USED IN ACID-PEPTIC DISEASES Calcium carbonateless soluble (partially absorbed)
reacts more slowlyrarely used (S.E.)formation of CO2 + CaCl2
constipationS.E.: Increase gastrin secretion (gastric distension), metabolicacidosis, combined consuption with milk (milk-alkali syndrome)(systemic antacid + milk)
I. DRUGS USED IN ACID-PEPTIC DISEASES NON-SYSTEMIC ANTACIDS 9 S.E.: osmotic diarrhea, bradycardia (renal failure -clearence inhibited ) 2. Aluminium – hydroxide gel (slow acting) Neuralizing capacity is weak pepsin adsorption, increases mucous secretion forms Al-chloride in the stomach (coat the mucosa), Cl - is released and is reabsorbed in the intestine > Al-phosphate S.E.: hypophosphatemia, anorexia, constipation 3. Combined preparations Al(OH) 3+Mg(OH) 2 e.g. MAALOX Antacids (OTC, non-prescreption) (1-1½ hours after meal) I. DRUGS USED IN ACID-PEPTic
I. DRUGS USED IN ACID-PEPTIC DISEASES - competitive antagonist of histamine - reduce basal, meal-stimulated and nocturnal acid secretion - gastrin, Ach-induced secretion - decrease pepsin and intrinsic factor B, Inhibition of HCl secretion 11 - promote ulcer healing - recurrence rate is 80-90% - 60-70% HCl inhibition/24h (90% during night time) - slight inhibition of gastrin, ACh effect - prophylactic use (NSAID), - no effect against H. pylori - tolerance during the administration - duodenal ulcers (4-8 weeks, 3 x 200 mg per day + night) - maintenance therapy
H2 rec. antagonists (competitive) PHARMACOKINETICS: Absoption: intestine (quickly) Metabolism: in the liver first-pass Biological efficiency: ~ 50%. T1/2: 1-4 hours excretio: glomerulus filtration 12 renal tubular secretion (renal failure!) safe drugs, side effects in < 3% of patients: diarrhea, constipation, headache, fatigue, mental status changes (confusion, hallucination, agitation) bradycardia, hypotension (H2 receptors in the heart), decreased libido, impotence and gynecomastia SIDE EFFECTS: interference with P450 drug metabolism pathways (cimetidine) - (e.g. phenytoin, warfarin, TCA, BZD) INTERFERENCE: A savcsökkentő gyógyszerek farmakológiája 3. A savtermelés
Cimetidine: (2x400-800 mg) S.E.: androgen receptor binding (loss of libido, impotence) increased prolactin, inhibition of oestradiol metabolism gynaecomastia or impotence ♂, galactorrhea ♀ cyt P450 inhibition, leading to effects on other drug metabolism H2 rec. antagonists I. DRUGS USED IN ACID-PEPTIC DISEASES 14 cyt P450 inhibition, leading to effects on other drug metabolism Ranitidine: (2x150 mg) S.E.: less, but tolerance leading to increasing dosage requirement Famotidine: (2x20 mg, most efficacious) Does not potentiate the effect of alcohol (via dehydrogenase) Nizatidine: (2x150 mg) little first pass effect, 90-100% bioavailability Ranitidine-bizmuth combination: PYLORID major adventage in combination with antibiotics
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