| Example |
Sodium citrate |
Aluminium Hydroxide/Calcium carbonate |
Omeprazole |
Ranitidine |
| Uses |
Aspiration prophylaxis |
Aspiration prophylaxis |
Aspiration prophylaxis, GORD, peptic ulceration |
Aspiration prophylaxis, GORD, peptic ulceration |
| Absorption |
Rapid absorption due to high water solubility |
Lower water solubility results in slower absorption and onset but no risk of alkalosis |
Absorbed in small bowel, high PO bioavailability |
50% PO bioavailability |
| Distribution |
|
|
Low VD of 0.3 L.kg-1 |
15% protein bound |
| Metabolism |
|
|
Prodrug, activated within parietal cell. CYP450 metabolised, inhibits CYP2C19 (reducing, among other things, the antiplatelet effect of clopidogrel) |
Partial hepatic by CYP450 |
| Elimination |
|
|
Renal of metabolites and active drug |
Renal of metabolites and active drug |
| Mechanism of Action |
Base reacts with gastric acid to produce salt and water |
Base reacts with gastric acid to produce salt and water |
Irreversible antagonism of the parietal H+/K+ ATPase |
Competitive antagonism of the (Gs) H2 receptor, which ↓ cAMP production, ↓ intracellular Ca2+, and ↓ activity of the H+/K+ ATPase |
| Resp |
Lower risk of pneumonitis if aspirated |
Greater risk of pneumonitis if aspirated |
Potentially increased severity of pneumonia if aspiration occurs (risk with micro-aspiration in long-term intubated patients) |
Pneumonitis/pneumonia as per PPI |
| CVS |
|
|
|
↓ HR, ↓ BP, and arrhythmogenic with rapid IV administration |
| Renal |
Potential metabolic alkalosis |
No risk of alkalosis |
Interstitial nephritis |
|
| GIT |
↑ Gastric pH |
↑ Gastric pH |
↑ Gastric pH (pH ↑ by ~1), ↓ volume of secretions |
|
| Other |
Taste bad |
|
|