Pepcid AC®, the brand name form of the generic medicine famotidine hydrochloride, belongs to a class of medicines known as H2 blockers. Other members of this class of drug are the popular gastric acid reducing drugs cimetidine and ranitidine. This drug is used to treat gastric and duodenal ulcers, gastroesophageal reflux disease, gastrointestinal hemorrhage, erosive esophagitis, heart burn, Zollinger-Ellison syndrome, and other pathological hypersecretory conditions. It is also used as a single dose intramuscular injection for the treatment of acute urticaria. The appropriate Pepcid AC® dosage varies according to which of these conditions it is being used to prevent or treat as well as the age and level of kidney function of the patient.
While the medication is generally used to treat existing conditions, in patients that have been successfully treated for duodenal ulcers it may be used to prevent their recurrence. Adult patients should initially receive a Pepcid AC® dosage of 40 mg taken orally once a day at bedtime or 20 mg twice daily according to the recommendations of the manufacturer. If necessary, a single maintenance dose of 20 mg may be given. The recommended Pepcid AC® dosage to prevent the recurrence of duodenal ulcers is 20 mg once per day. Tabletized Pepcid AC® dosage guidelines for patients suffering from gastric ulcers are the same as those for those with duodenal ulcers.
Adults suffering from gastroesophageal reflux disease should be given 20 mg of the drug twice daily. This treatment regimen should be continued for up to six weeks. As of 2011 treatment longer than six weeks has not been shown to be more effective than shorter periods of therapy. Any adults suffering from the more serious erosive esophagitis may require a higher dose. The recommended Pepcid AC® dosage for these patients is between 20 and 40 mg given twice per day and may be continued for as many as 12 weeks.
Children between the ages of one and 16 years of age who are receiving treatment for gastroesophageal reflux disease may need a reduced Pepcid AC® dosage. Initially, 1 mg per 2.2 lbs (1 kg) of body weight should be divided into two equal oral doses to be given 12 hours apart. If this dose does not prove to be effective, the dose may be increased up to 2 mg per 2.2 lbs (1 kg) up to a maximum of 80 mg per day. For children unable to take the medication orally, it may instead be administered intravenously at 0.25 mg per 2.2 lbs (1 kg) every 12 hours up to a maximum of 40 mg or 0.5 mg per 2.2 lbs (1 kg) per day.
All of the above dosage recommendations must be adjusted for patients suffering from moderate-to-severe reduction in kidney function. For patients with creatine chloride levels of less than 50 ml per minute, either the recommended Pepcid AC® dosage should be cut in half or the dosing interval should be increased to between 36 and 48 hours. A failure to do so may produce unpleasant central nervous system side effects.