Unit1_Pharm Flashcards
_______ suppression is still the treatment of choice for acute ulcers and given alone these agents will lead to ulcer healing.
Acid
Acid suppression is still the treatment of choice for _____ ulcers and given alone these agents will lead to ulcer healing.
acute
_________ therapy is necessary to reduce the rate of recurrence of gastric ulcers (50-80% success) and duodenal ulcers (90-95% success) antibiotic therapy is critical.
Antibiotic
These antibiotics are used as components of “triple” or “quadruple” therapy with proton pump inhibitors and H2 antagonists.
What makes up Triple ABX therapy?
Clarithomycine \+ Amoxicillin-or-Metronidazole \+ PPI
What makes up Quadruple ABX therapy?
Bismuth subsalicylate \+ Metronidazole \+ Tetracycline \+ PPI or H2 Antagonist
What makes up Sequential ABX therapy?
Amoxicillin-PPI (5 days) then
Clarithromycin-Tinidazole-PPI (5 days)
What Drug is Administered as prodrug, absorbed into systemic circulation, then diffuses into parietal cells of stomach where proton catalyzed formation of the active sulfenamide “traps” the drug in the acidic secretory canniculi?
Proton Pump Inhibitors
What cells in the GI do PPIs act on?
parietal cells in the stomach
What is the active form of a PPI?
Active Silfenamide
What type of inhibition does a PPI do?
irreversible inhibition of an enzyme [H+/K+ ATPase]
How long does it take for the synthesis of new enzyme that is irreversibly blocked by PPIs? Therefore, this means that PPIs result in what percentage reduction in acid production?
18 hours are needed to synthesize new H+/K+ ATPase.
80-95% reduction in acid production. (even tho the half-life of PPIs are 0.5 to 2.0 hours)
How long does it take a PPI to reach steady state levels?
2-5 days. b/c not all pumps are active at the time of Rx use.
Which PPIs are the most effective?
They all have the same effects
PPI are highly protein-bound with bioavailability of 40-90%. What can you do to improve bioavailability?
Admin as an enteric-coated pill or with Sodium Bicarb.
Best to give about 1 hour before meal so that peak plasma level occurs when your pumps are active.
What is the metaboism profile of PPIs?
rapid first pass in liver via CYP450. caution with pt. w./ hepatic issues.
no drug accum in chronic renal failure with once-daily dosing.
What diz/Sx can be treated with PPIs?
- GERD
- Peptic Ulcer Diz
- NSAID-induced ulcers
- Prevention of stress gastritis
- Zollinger-Ellison Syndrome
Which PPI fucks with a blood thinner? What is the name of that blood thinner?
Omeprazole inhibits conversion of clopidogrel, and anti-platelet agent (prevents crosslinking of platelets)
Omeprazole [Prilosec] / Esomeprazole [Nexium], Lansoprazole [Prevacid] are what class of drugs?
PPIs
Omeprazole is available OTC
What is the MOA of H2 Receptor Antagonist?
reversible, competitive block of PARIETAL cells H2 receptors on basolateral membrane.
Better at blocking nocturnal (basal, H2-mediated) acid secretion (90%) than meal-stimulated (ACh- and gastrin-mediated, 60-80%). Since suppression of nocturnal acidity is key to duodenal ulcer healing, evening dosing of H2 antagonists is usually adequate therapy.
Describe the PK profile of H2 receptor antagonist.
Rapid absorption from GI tract, decrsed with antacid use.
Less protein binding than PPIs.
Some Hepatic metabolism (no adjustment needed for liver diz)
Elim = renal excretion [need dose adjustment with impaired renal function, think old folks]
half-life = 1 - 4 hours
What are the clinical uses of H2 receptor antagonist?
- GERD
- Peptic Ulcer Disease
- Stress-related gastritis
What are the basic common side effects of H2 receptor ANTAGONIST?
- dizziness
- diarrhea
- constipation
- headache
- some CNS dysfunction
overall they are well tolerated
What are the endocrine ADRs ~w/ H2 receptor antagonists?
@ high does ==>
- Gynecomastia
- Galactorrhea
- decreased sperm count
What are the DDi ~w/ H2 receptor antagonists?
- Cimetidine inhibits CYP450 oxidative metabolism.
(Fucks with the effects or toxicity of number of drugs (theophylline, warfarin, phenytoin, carbamazepine, ketoconazole, itraconazole, benzodiazepines)
-All anti-secretory agents can decrease ketoconazole absorption by causing an increase in gastric pH (more basic)
Sucralfate [Carafate] is what class of drug?
Mucosal Protective Agents
What is the MOA of Sucralfate?
during acid-induced damage, pepsin will hydrolyze mucosal proteins causing erosion and ulcerations. this process is inhibited by sulfated disaccharide aluminum salt that SELECTIVELY binds to necrotic ulcer tissue to form a protective layer.
[up to 6 hours of protection per dose]
What are the other possible 2/nd actions of Sucralfate?
decrease back diffusion of H+ and binds to pepsin and bile acids.
May stimulate PGE and Epidermal GF production.
What are the clinical uses of Sucralfate?
decreased use.
limited to adjunct Tx.
What are the ADRs ~w/ Sucralfate?
few. Constipation most common
Misoprostol [Cytotec] is what class of drug?
PGE1 analog
What is the MOA of Misoprostol?
PGE normally act on stomach parietal cells to inhibit cAMP formation –> DECREASE H+ secretion.
PGE also stimulate acid neutralizing HCO- formation and cytoprotective mucus formation.
Misoprostol is a PGE1 analog = increases this normal physiological func.
acid-suppression is does-related [up to 85-95%]
Describe the PK of Misoprostol?
- Oral, rapid absorption (w/in 30min)
- rapidly de-esterified to active metabolite, 30-min half-life.
- dosed 3-4/day
What are the clinical uses of Misoprostol?
Tx NSAIDs induced GI ulceration, but rarely used d/t to 4-dose/day and ADRs
What are the side effects of Misoprostol use?
- Diarrhea
- No-No-4-Prego
What drug class can be used in pain relief (healing) d/t peptic ulceration and acute gastritis?
Gastric Antacids
What would be the IDEAL properties of gastric antacids? (4)
- rapidly increase stomach pH to 4-5. (PD)
- be non-absorbable (PK)
- be long-acting (PK)
- no ADRs
Which type of antacids have the HIGHEST levels of systemic actions? (i.e. highest systemic absorption)
NaHCO3 (Sodium bicarb)
Al3+, Mg2+, Ca2+ are less absorbed and cleared with normal renal func.
Which antacids has diarrhea as an ADR?
Which one has constipation as an ADR?
Mg2+ = diarrhea
Ca2+ & Al3+ = constipation