Pepcid Complete Disease Interactions

Elevated serum concentrations of calcium and phosphate can exceed the solubility level and result in calcium- phosphate precipitates that deposit in vascular and renal systems as well as other soft tissues of the body. Therapy with calcium should be administered with extreme caution in patients with hyperphosphatemia (hypoparathyroidism or severe renal impairment). Administration of oral calcium acetate or calcium carbonate, in addition to providing calcium, complexes phosphates within the GI tract. These complexes are eliminated in the feces. Clinical monitoring of serum calcium and phosphate concentrations is necessary.

Calcium is involved in cardiac muscle contraction and electrical impulse conduction. Therapy with calcium salt formulations (particularly IV) should be administered cautiously to patients with cardiac disease. Patients receiving cardiac glycosides and concomitant IV calcium may experience arrhythmias. Therapy with IV calcium should be administered slowly and at reduced dosages in patients with cardiac disease.

Calcium is absorbed from the intestinal tract by active transport and passive diffusion. Malabsorption syndromes (celiac disease, GI resection), deficiency of vitamin D, parathyroid hormone, or calcitonin, or an alkaline gastric pH (achlorhydria, carbonate or phosphate salts) can decrease the absorption of oral formulations of calcium. Calcium is available in oral and parenteral formulations.

Absorption of oral calcium formulations may be altered and elimination of calcium by the kidney decreased with renal impairment. Hyperphosphatemia occurs during renal failure. Calcium acetate or calcium carbonate, in addition to providing calcium, complexes phosphates within the GI tract. Calcium carbonate can partially correct metabolic acidosis associated with chronic renal failure. Clinical monitoring of renal function and serum calcium and phosphate concentrations is necessary.

Hypercalciuria, with or without hypercalcemia, may occasionally occur in patients with sarcoidosis. Elevated calcium levels may result from increased intestinal absorption of calcium, which is related to the extrarenal production of vitamin D by mononuclear phagocytes present within the sarcoid granuloma. Therapy with calcium salts should be administered cautiously and only if necessary in patients with sarcoidosis.

Histamine H2 receptor antagonists should not be used in the presence of vomit with blood, or bloody or black stools. These might be serious conditions and the diagnosis needs to be ruled out.

The use of laxatives is contraindicated in patients with inflammatory bowel disease. Patients with inflammatory bowel disease may experience colonic perforation with use of stimulant laxatives.

The use of laxatives is contraindicated in patients with intestinal obstruction disorders. Patients with intestinal obstruction disorders may need their underlying condition treated to correct the constipation. Some laxatives require reduction in the colon to their active form to be effective which may be a problem in patients with intestinal obstruction.

Magnesium is eliminated by the kidney. The serum concentration of magnesium is increased in patients with renal impairment. Magnesium toxicity includes CNS depression, muscular paralysis, respiratory depression, hypotension and prolonged cardiac conduction time. Disappearance of the patellar reflex is a useful clinical sign of magnesium intoxication. Therapy with magnesium should be administered cautiously and dosages should be modified in patients with compromised renal function. Clinical monitoring of serum magnesium levels is recommended.

Famotidine is partially eliminated by the kidney as unchanged drug, the extent of which is dependent upon the route of administration (25% to 30% oral; 65% to 70% intravenous). The elimination half-life of famotidine may be prolonged considerably in patients with severe renal impairment (CrCl < 10 mL/min), possibly exceeding 20 hours and approaching approximately 24 hours in anuric patients. Since central nervous system adverse effects such as grand mal seizures and psychic disturbances have been reported in patients with moderate (CrCl < 50 mL/min) and severe renal impairment, dosage adjustments are recommended for these patients. Reducing the normally recommended dosage by one-half or prolonging the dosing interval to 36 to 48 hours may be appropriate, depending on the patient's clinical response.