Histamine H2 Antagonists

Type of Drug
Anti-ulcer drugs

How The Drug Works

Histamine H2 antagonists reduce acid in the stomach by blocking one of the chemical transmitters (histamine) that is responsible for stimulating the production of stomach acid.

Uses

To treat and prevent recurrence of duodenal (first part of small intestine) ulcers.
To treat gastric (stomach) ulcers.
To prevent recurrence of gastric (stomach) ulcers (ranitidine only).
To treat hypersecretory (increased acid secretion) conditions (eg, Zollinger ­ Ellison syndrome)
To treat erosive gastroesophageal reflux disease (GERD) (reflux of stomach acid into the food pipe, which causes heartburn).
To treat (over-the-counter cimetidine, famotidine, and nizatidine only) or prevent (over-the-counter cimetidine, famotidine, and nizatidine only) heartburn, acid indigestion, or sour stomach.

Other Uses : Occasionally doctors may prescribe:

Cimetidine - To prevent stress-induced or peptic ulcers and certain types of respiratory complications (aspiration pneumonia) during anesthesia. It may be used to treat hyperparathyroidism (overactive parathyroid gland), indigestion, ringworm, herpes virus infections, chronic warts, chronic hives, allergic skin reactions, acetaminophen overdose, colorectal cancer, and abnormal hair growth in women.

Famotidine - To prevent stress-induced or peptic ulcers and certain types of respiratory conditions (aspiration pneumonia) during anesthesia. It may also be used to treat bleeding of the stomach or intestines.

Nizatidine - To treat peptic ulcers.

Ranitidine - To prevent stomach and intestinal damage associated with long-term nonsteroidal anti-inflammatory drug therapy (eg, ibuprofen), stress-induced or peptic ulcers, certain types of respiratory complications (aspiration pneumonia) during anesthesia, and to treat bleeding of the stomach or intestines.

Phenylketonuric Patients: Some of these products contain phenylalanine. Consult your doctor or pharmacist.

Pregnancy: There are no adequate and well-controlled studies in pregnant women. Use only if clearly needed and the potential benefits to the mother outweigh the possible hazards to the fetus

Breastfeeding: Cimetidine, famotidine, nizatidine, and ranitidine appear in breast milk. Consult your doctor before you begin breastfeeding.

Children: Safety and effectiveness of nizatidine in children have not been established. Safety and effectiveness of famotidine in children under 1 year of age and of ranitidine in children under 1 month of age have not been established. Cimetidine use is not usually recommended in children less than 16 years of age. Over-the-counter cimetidine, famotidine, nizatidine, or ranitidine use is not recommended in children under 12 years of age.

Elderly: Safety and effectiveness are similar to younger patients. Elderly patients may have reduced kidney function. Smaller cimetidine doses may be prescribed.

Lab tests may be required to monitor therapy. Tests may include liver function tests.

Drug Interactions

Tell your doctor or pharmacist if you are taking or if you are planning to take any over-the-counter or prescription medications or dietary supplements while taking histamine H2 antagonists. Doses of one or both drugs may need to be modified or a different drug may need to be prescribed. The following drugs and drug classes interact with histamine H2 antagonists:

Cimetidine only -
Aminoquinolones (eg, chloroquine)
Anticoagulants, oral (eg, warfarin)
Beta-blockers (eg, propranolol)
Benzodiazepines (except larazepam, oxazepam, temazepam)
Carbamazepine (eg, tegretol)
Carmustine (BiCNU)

Side Effects

Every drug is capable of producing side effects. Many histamine H2 antagonist users experience no, or minor, side effects. The frequency and severity of side effects depend on many factors including dose, duration of therapy, and individual susceptibility. Possible side effects include.

Digestive Tract: Diarrhea; constipation; stomach pain.

Nervous System: Confusion; hallucinations; fatigue; dizziness; sleepiness; headache.

Other: Impotence; breast enlargement (males).

Guidelines for Use

Dosage is individualized. Take exactly as prescribed or as directed by the package label, Do not stop taking or change the dose, unless directed by your doctor. May be taken without regard to meals.

If a dose is missed, take it as soon as possible. If several hours have passed or it is nearing time for the next dose, do not double the dose to catch up, unless advised to do so by your doctor. If more than one dose is missed or it is necessary to establish a new dosage schedule, contact your doctor or pharmacist.

It may be necessary to make lifestyle changes to assist in the treatment and prevention of ulcers and other digestive problems. These changes may include stress-reduction programs, exercise, and dietary changes.

Notify your doctor if you experience diarrhea, dizziness, confusion, anxiety, depression, disorientation, agitation, or hallucinations.

Notify your doctor if you experience any symptoms that suggest a bleeding ulcer, such as black. tarry stools or "coffee-ground" vomit.

Antacids can be used at the same time to help control acid symptoms.

Stagger doses of antacids and cimetidine or ranitidine.

May cause dizziness or drowsiness. Use caution while driving or performing other tasks requiring alertness, coordination, or physical dexterity.

Over-the-counter products - Contact your doctor if you have trouble swallowing or persistent stomach pain. Do not take maximum daily dosage for more than 2 weeks continuously except under the advice and supervision of your doctor.

Famotidine suspension - Shake well before using, Do not freeze.

Discard unused suspension after 30 days.

Famotidine orally disintegrating tablets - Keep tablets in unopened package until time of use. Open tablet blister pack with dry hands and place tablet on tongue to dissolve and be swallowed with saliva. No water is needed for taking the tablet.

Pepcid Complete - Do not swallow tablets whole; chew completely before swallowing.

Ranitidine effervescent tablets or granules - Dissolve in 6 to 8 oz of water before drinking.

Inform your doctor if you are pregnant, become pregnant, are planning to become pregnant, or are breastfeeding.

Lab tests or exams may be required to monitor therapy. Be sure to keep appointments.

Store at room temperature in a tight container away from light.