Table 2.
Features and limitations of different types of antacid salts.
| Saltsa |
||||
|---|---|---|---|---|
| Calcium | Sodium | Magnesium | Aluminum | |
| Speciesb | Carbonate | Bicarbonate, citrate | Hydroxide, carbonate, oxide, trisilicate | Hydroxide, carbonate, phosphate, glycinate |
| Category | Non-absorbable | Absorbable | Non-absorbable | Non-absorbable |
| ANC (mEq/15 mL)c | 58 | 17 | 35 | 29 |
| Maximum daily dosage limit (mEq)d | 160 | 200 (≤60 years old) and 100 (>60 years or older) | 50 | NA |
| Limitations | • Constipation and flatulence• Systemic alkalosis and hypercalcemia on long term use• Occasional milk-alkali syndrome in patients taking more than the recommended dose | • Non-serious, stomach/gut irritations that could cause gas or bloating | • Dose-related diarrhea• Flushing• Hypotension• Vasodilation• Hypermagnesemia | • Hypomagnesemia• Hypophosphatemia• Constipation• Anemia |
| FDA category for antacid use in pregnancye | None | None | None | None |
| Contraindications | ||||
| Renal impairment | No | Yes | Yes | Yes |
| Hepatic impairment | No | Yes | No | No |
| Allergy to the antacid ingredient(s) in the formulation | Yes | Yes | Yes | Yes |
| Others | • Patients with hypercalcemia, hypercalciuria, nephrocalcinosis, and nephrolithiasis• Patients on a low-phosphate diet | • Patients on a sodium- restricted diet, e.g., those with hypertension or congestive heart failure | • Patients with severe diarrhea • Patients with neuromuscular disease such as myasthenia gravis | • Patients with constipation |
aA salt is a chemical compound consisting of an ionic assembly of positively charged cations and negatively charged anions. The specific salts of active pharmaceutical ingredients are often formed to achieve desirable formulation properties. 96
bChemical species are specific forms of a particular element, such as an atom, molecule, ion, or radical. For example, chloride is an ionic species. 97
cThe potency of an antacid is generally expressed in terms of its ANC, which is defined as the number of mEq of 1 N HCl that are brought to pH 3.5 in 15 minutes (or 60 minutes in some tests) by a unit dose of the antacid preparation. 98
dAs per the federal register of the US FDA 99
eAntacids carry a FDA pregnancy category of None (N), meaning these drugs have not been classified by the FDA. 65
mEq, milliequivalents; ANC, acid-neutralizing capacity.