Antacids are a group of drugs that have been on the market for several years. They were initially first-line defense against peptic ulcer disease; however, the discovery of proton pump inhibitors revolutionized the treatment of peptic ulcer disease. Currently, antacid use is restricted for the relief of mild intermittent gastroesophageal reflux disease (GERD) associated heartburn . The estimated prevalence of heartburn at least once per week in North America ranges from 18% to 28% with 25% adults reporting heartburn on a daily basis. ,,
Antacids are medications that do not require a prescription, in other words, they are self-prescribed. Antacids are a combination of various compounds with various salts of calcium, magnesium, and aluminum as the active ingredients. The antacids act by neutralizing the acid in the stomach and by inhibiting pepsin, which is a proteolytic enzyme. Each of these cationic salts have a characteristic pharmacological property that determines its clinical use. Antacids have been used for the following:
The antacids reduce the acid reaching the duodenum by neutralizing the acid present in the stomach. The main objectives are:
The salts' mechanism of neutralization of acid varies, and each salt has a different mechanism with the ultimate goal of acid neutralization.
The formulation of aluminum hydrochloride and water results in neutralization of the acid in the stomach. It is also known to inhibit pepsin activity. Aluminum hydroxide is complexed with a sulfated polysaccharide sucrose octasulfate to form sucralfate. This complex does not have a significant buffering action against the acid or has no effect on the pepsin secretion and does not alter the gastric acid production in any way., Nevertheless, it is known to heal chronic ulcers and prevent acute mucosal damage induced chemically by reducing access to pepsin and acid. Sucralfate likes its aluminum hydroxide component is known to stimulate angiogenesis and granulation tissue formation.
Aluminum hydroxide is also useful in hyperphosphatemia due to its ability to bind phosphate in the gastrointestinal (GI) tract and subsequently prevent absorption of phosphate .
They neutralize gastric acidity resulting in increased gastric and duodenal bulb pH; they additionally inhibit the proteolytic activity of pepsin if the pH is greater than 4 and increase lower esophageal sphincter tone. The calcium released from calcium carbonate is known to increases peristalsis in the esophagus pushing the acid into the stomach and provide relief from symptoms of heartburn. The calcium salts also form combined insoluble compounds with dietary phosphate and prevent the absorption of later.
The acid neutralizing mechanism of the antacids is well understood as mentioned above. In addition to this, there are other mechanisms that add to the ulcer healing properties of this class of drugs. The exact mechanism is still unclear, but it is believed to be a combination of
The dose for antacids depends upon the age of the patient, the purpose of administration (neutralization of acid or off-label use) and presence of other comorbidities like renal or hepatic impairment. As all the forms of these medications are available as over the counter medication, the dosing recommendation varies by product/and or manufacturer.
Aluminum Hydroxide (Antacid)
Calcium Carbonate (Antacid)
It is used up to a maximum dose of 8000 mg per day up to 2 weeks with 1 to 4 tablets for symptomatic relief.
The total dose is not to exceed 2000 mg per day.
Pregnancy and Breastfeeding
Antacids containing aluminum salts are safe to be used in pregnant women as well as for women during labor for aspiration prophylaxis. The information regarding the use of aluminum-containing antacids in breastfeeding females has not been studied, but aluminum is known to be endogenous to breast milk., In case of calcium-containing antacids excessive use is to be avoided in pregnant women as calcium crosses the placenta. The amount of calcium reaching the fetus is dependent on the physiological changes in the mother. The maternal calcium intake also affects the amount of calcium excreted in the breast milk; it is believed that the use of calcium-containing antacids is safe during breastfeeding. 
The adverse effects are prominent in the infants and the elderly population. The chronic use of antacids in this population is not recommended due to safety concerns.
Aluminum use is associated with increased risk of toxicity in individuals with renal failure and infants. It presents as:
The adverse reactions often seen with this group of antacids are:
The absolute contraindication is hypersensitivity to any component of the formulation. Also, the drug is to be used with caution in patients with:
The average therapeutic dose of antacid is 10 to 15 mL (1 tablespoon or 1 package content) of liquid or 1 to 2 tablets 3 to 4 times a day. Periodic monitoring of calcium and phosphorus levels is suggested in patients on chronic therapy.
No information is available regarding toxicities caused by aluminum- and calcium-containing antacids. However, antacids are to be used cautiously in the high-risk population mentioned above.
Antacids are available as over the counter medications, meaning that patients do not require a prescription to obtain them. This results in the improper use of these medications with little to no relief of symptoms. There is a need to educate patients regarding the importance of correct mode of administration, time of administration, and dosage for the prompt and prolonged relief of symptoms. These medications only provide symptomatic relief, which may mask an underlying disorder, but lack of awareness in this regard delays diagnosis in health conditions like GERD, peptic ulcer, gastric ulcer, and hiatal hernia. Although these medications do not cause toxicities in high doses, it is imperative to understand their interaction with other medications especially in patients on polypharmacy. The physicians, nurses, pharmacists, and the pharmaceutical companies have a combined responsibility to educate the patients regarding the safe use of these medications to improve outcomes.