Upper GI Pharmacology Flashcards

1
Q

Antacid pharmacokinetics

A
tablets/powder, suspension
Poorly absorbed (unless poor renal function), thus minimal undesired systemic side effects
Di/tri-valent cations; may chelate other drugs, separate dosing
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2
Q

Antacid MOA

A

Locally buffer H+ to increase pH

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3
Q

Antacid indications

A

heartburn, dyspepsia

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4
Q

Antacid SE

A

Mg-containing: osmotic diarrhea (explosive)
Ca-containing: constipation, hypercalcemia, calculi, bloating, nausea (due to CO2 liberated)
Al-containing: constipation, hyperphosphatemia

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5
Q

H2 antagonist prototypes

A

ranitidine, cimetidine

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6
Q

H2 antagonist PK

A

po; some iv and im
rapidly absorbed
renal elimination (filtration and secretion) - adjust dosing in renally impaired patients

Cimetidine: notorious CYP450 blocker

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7
Q

H2 antagonist MOA

A

H2 receptors on parietal cells mediate basal, nocturnal, and meal-stimulated release of acid (histamine binding stimulates H/K ATPase via cAMP)
Reversible blockage

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8
Q

H2 antagonist indications

A

GERD
PUD
Dyspepsia
Prevention of bleeding from stress-related gastritis

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9
Q

H2 antagonist SE

A

generally well-tolerated
diarrhea/constipation, headache, fatigue, MSK pain
Cimetidine only: gynecomastia and galactorrhea

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10
Q

PPI prototypes

A

omeprazole, pantoprazole

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11
Q

PPI PK

A

must be absorbed into systemic circulation
act locally on GI tract cells (parietal cells)
Prodrugs: activated in acidic canaliculi of parietal cells
hepatic clearance - adjust dosing in liver impaired patients

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12
Q

PPI MOA

A

antagonist of proton-secreting pump in stomach (K/H pump) on parietal cells
irreversible

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13
Q

PPI indications

A

gastric and duodenal ulcers, NSAID-induced ulcers
GERD
Pathological hypersecretory conditions (Zollinger-Ellison, where levels of hormone are increased due primarily to gastrinoma tumour of non-beta islet cells in the pancreas)

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14
Q

PPI SEs

A

generally well-tolerated short term
nausea, ab pain, constipation/diarrhea, flatulence (alteration in intestinal flora due to pH change)
less common: hypergastrinemia, due to rebound secretion of gastric acid if PPI is stopped after short-term use

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15
Q

Misoprostol PK

A

short half-life

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16
Q

Misoprostol MOA

A

PG analogue
endogenous PGE2 binds EP3 on parietal cells –> reduces activity of proton pump and stimulates mucin and bicarb secretion to bolster mucosal barrier
endogenous PGE2 is made by COX1
PGE-1 analogues (misoprostol) given as adjuncts in patients on NSAIDs

17
Q

Misoprostol indications

A

NSAID-induced gastric ulcer

18
Q

Misoprostol SEs

A

diarrhea, abd cramping (stimulates smooth muscle contraction in GI and uterus)

19
Q

Sucralfate PK

A

local GI action, minimal absorption (fecally excreted)
activated by acid
contains Al, which is excreted renally - adjust for renal impaired patients

20
Q

Sucralfate MOA

A

complex of sucrose and AlOH –> viscous paste in acid aqueous media (direct
stimulates PG synthesis of mucus and bicarb secretion (indirect)

21
Q

Sucralfate indications

A

Tx and prevention of gastric and duodenal ulcer

22
Q

Sucralfate SE

A

constipation (Al)

minimal systemic effects due to poor absorption

23
Q

Bismuth MOA

A

form protective barrier on ulcer
enhance PG, mucus, bicarb secretion
inhibit H. pylori growth and adherence

24
Q

Bismuth indications

A

Adjunctive therapy in H. pylori eradication

acute diarrhea

25
Bismuth SE
black tarry stool (benign discolouration, commonly mistaken for blood) benign discolouration of tongue constipation tinnitus
26
Prokinetic prototypes
metoclopramide, domperidone
27
Prokinetic PKs
metoclopramide: rapidly absorbed, hepatic metabolism, renal excretion, oral/parental dosage Domperidone: rapidly absorbed, low oral bioavailability because of extensive first pass mechanism (increased availability with food)
28
Prokinetic MOAs
endogenous dopamine inhibits GI motility, since D2 receptors inhibit ACh release D2 antagonists --> increase LES tone, stimulates GI contraction (upper) also anti-nauseants via central inhibition of vomiting centre
29
Prokinetic indications
gastroparesis, nausea/vomiting (anti-emetic) GERD facilitate small bowel intubation
30
Antacid prototypes
Ca carbonate | Mg, Al hydroxide