Cimetidine

What is Cimetidine?

• Cimetidine (Tagamet; Tagamet HB) is a histamine H2-receptor antagonist widely used for treatment of acid-peptic disease and heartburn.

Cimetidine

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What are the uses of this medicine?

Cimetidine (Tagamet; Tagamet HB) is used for:

• Short-term treatment of active duodenal ulcer
• Maintenance therapy for duodenal ulcer patients at reduced dosage after healing of active ulcer
• Short-term treatment of active benign gastric ulcer
• Erosive gastroesophageal reflux disease (GERD)
• The treatment of pathological hypersecretory conditions (i.e., Zollinger-Ellison Syndrome, systemic mastocytosis, multiple endocrine adenomas)

How does this medicine work?

• Cimetidine (sye met' i deen) was the first H2 blocker introduced into clinical practice in the United States and remains a commonly used agent for treatment of duodenal and gastric ulcer and gastroesophageal reflux disease.
• The H2 blockers are specific antagonists of the histamine type 2 receptor, which is found on the basolateral (antiluminal) membrane of gastric parietal cells.
• The binding of cimetidine to the H2 receptor results in inhibition of acid production and secretion, and improvement in symptoms and signs of acid-peptic disease.
• The H2 blockers inhibit an early, “upstream” step in gastric acid production and are less potent that the proton pump inhibitors, which inhibit the final common step in acid secretion.
• Nevertheless, the H2 blockers inhibit 24 hour gastric acid production by about 70% and are most effective in blocking basal and nocturnal acid production.

Who Should Not Use this medicine ?

This medicine cannot be used in patients who:

• known to have hypersensitivity to the product.

What drug interactions can this medicine cause?

• Tell your doctor and pharmacist what other prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or plan to take.

Especially tell your doctor if you take:

• anticoagulants ('blood thinners') such as warfarin (Coumadin)
• antidepressants (mood elevators) such as amitriptyline (Elavil), amoxapine (Asendin), clomipramine (Anafranil), desipramine (Norpramin), doxepin (Adapin, Sinequan), imipramine (Tofranil), nortriptyline (Aventyl, Pamelor), protriptyline (Vivactil), and trimipramine (Surmontil)
• chlordiazepoxide (Librium)
• clopidogrel (Plavix), diazepam (Valium)
• lidocaine (Xylocaine)
• metronidazole (Flagyl)
• nifedipine (Adalat, Procardia)
• phenytoin (Dilantin)
• propranolol (Inderal)
• theophylline (Theobid, Theo-Dur)

• If you are taking antacids, digoxin, ketoconazole, or iron salts, take them 2 hours before cimetidine.

Is this medicine FDA approved?

• Cimetidine was first approved for use in the United States in 1977 and is still used widely both by prescription and in over-the-counter forms.
• The listed indications for cimetidine include duodenal and gastric ulcer disease, gastroesophageal reflux and prevention of stress ulcers.

How should this medicine be used?

Recommended dosage: For Active Duodenal Ulcer:

• 300 mg four times daily, with meals and at bedtime or 400 mg twice daily, in the morning and at bedtime.
• or 800 mg at night for up to 8 weeks.

Maintenance Therapy for Duodenal Ulcer:

• In those patients requiring maintenance therapy, the recommended adult oral dose is 400 mg at bedtime.

Active Benign Gastric Ulcer:

• The recommended adult oral dosage for short-term treatment of active benign gastric ulcer is 800 mg at bedtime, or 300 mg four times a day with meals and at bedtime.

Erosive Gastroesophageal Reflux Disease (GERD):

• The recommended adult oral dosage for the treatment of erosive esophagitis that has been diagnosed by endoscopy is 1600 mg daily in divided doses (800 mg twice daily or 400 mg four times daily) for 12 weeks.

Pathological Hypersecretory Conditions (such as Zollinger-Ellison Syndrome):

• Recommended adult oral dosage: 300 mg four times a day with meals at bedtime.
• In some patients it may be necessary to administer higher doses more frequently.
• Doses should be adjusted to individual patient needs, but should not usually exceed 2400 mg per day.

Dosage Adjustments for Patients with Impaired Renal Function:

• The recommended dosage is 300 mg every 12 hours orally.

Administration:

• Cimetidine comes as a tablet and a liquid to take by mouth.
• It is usually taken once a day at bedtime or two to four times a day with meals and at bedtime.
• Over-the-counter cimetidine is usually taken once or twice a day with a glass of water.
• To prevent symptoms, it is taken within 30 minutes before eating or drinking foods that cause heartburn.
• Do not take over-the-counter cimetidine for longer than 2 weeks unless your doctor tells you to.
• If symptoms of heartburn, acid indigestion, or sour stomach last longer than 2 weeks, stop taking cimetidine and call your doctor.

What are the dosage forms and brand names of this medicine?

This medicine is available in fallowing doasage form:

• As tablet, for oral administration, contains 300 mg, 400 mg, or 800 mg cimetidine
• As a liquid

This medicine is available in fallowing brand namesː

• Tagamet; Tagamet HB

What side effects can this medication cause?

The most common side effects of this medicine include:

• diarrhea, constipation, fatigue, drowsiness, headache and muscle ache

Less coomon, but serious side effects may include:

• Dizziness and somnolence
• mental confusion
• agitation
• psychosis
• depression
• anxiety
• hallucinations
• disorientation
• Gynecomastia
• Reversible impotence
• Decreased white blood cell counts
• increases in serum transaminase
• allergic reactions including anaphylaxis and hypersensitivity vasculitis
• bradycardia, tachycardia and A-V heart block
• arthralgia and myalgia
• Mild rash
• Stevens-Johnson syndrome
• epidermal necrolysis
• erythema multiforme
• exfoliative dermatitis
• generalized exfoliative erythroderma
• strongyloidiasis hyperinfection
• pneumonia

What special precautions should I follow?

• Rare instances of cardiac arrhythmias and hypotension have been reported following the rapid administration of cimetidine hydrochloride by intravenous bolus.
• Reversible confusional states have been observed on occasion, predominantly, but not exclusively, in severely ill patients. Advancing age (50 or more years) and preexisting liver and/or renal disease appear to be contributing factors.
• Cimetidine is secreted in human milk and, as a general rule, nursing should not be undertaken while a patient is on this drug.
• In immunocompromised patients, decreased gastric acidity, including that produced by acid-suppressing agents such as cimetidine, may increase the possibility of a hyperinfection of strongyloidiasis.
• Cimetidine has been linked to rare instances of clinically apparent acute liver injury.
• imetidine is metabolized by and can inhibit several isoforms of the hepatic cytochrome P450 system (CYP 1A2, 2C9 and 2D6), which can result in significant drug-drug interactions if administered with agents that rely upon their metabolism by these microsomal enzymes (such as digoxin, warfarin, oral contraceptives, isoniazid and phenytoin).

What to do in case of emergency/overdose?

Symptoms of overdosage may include:

• respiratory failure
• tachycardia
• unresponsiveness
• mental deterioration

Management of overdosage:

• In case of overdose, call the poison control helpline of your country. In the United States, call 1-800-222-1222.

• Overdose related information is also available online at poisonhelp.org/help.
• In the event that the victim has collapsed, had a seizure, has trouble breathing, or can't be awakened, immediately call emergency services. In the United States, call 911.
• Respiratory failure and tachycardia that may be controlled by assisted respiration and the administration of a beta-blocker.
• The usual measures to remove unabsorbed material from the gastrointestinal tract, clinical monitoring, and supportive therapy should be employed.

Can this medicine be used in pregnancy?

• Pregnancy category B.
• There are, however, no adequate and well-controlled studies in pregnant women.
• Because animal reproductive studies are not always predictive of human response, this drug should be used during pregnancy only if clearly needed.

Can this medicine be used in children?

• Cimetidine therapy cannot be recommended for pediatric patients under 16, unless, in the judgment of the physician, anticipated benefits outweigh the potential risks.

What are the active and inactive ingredients in this medicine?

Active ingredient:

• cimetidine

Inactive ingredients:

• corn starch, magnesium stearate, microcrystalline cellulose, povidone, sodium lauryl sulfate and sodium starch glycolate. The coating for the tablets contains: carnauba wax, hypromellose, polyethylene glycol, polysorbate 80, talc, titanium dioxide, and triethyl citrate. The coating for the 300 mg and 400 mg tablets also contains D&C Yellow No. 10 Aluminum Lake, FD&C Blue No. 1 Aluminum Lake, and FD&C Yellow No. 6 Aluminum Lake.

Who manufactures and distributes this medicine?

Manufactured In Canada By:

• TEVA CANADA LIMITED
• Toronto, Canada M1B 2K9

Manufactured For:

• TEVA PHARMACEUTICALS USA, INC.
• North Wales, PA

What should I know about storage and disposal of this medication?

• Store at 20° to 25°C (68° to 77°F).
• Dispense in a tight, light-resistant container, as defined in the USP, with a child-resistant closure (as required).
• KEEP THIS AND ALL MEDICATIONS OUT OF THE REACH OF CHILDREN.

The antiulcer agents in clinical use

Proton Pump Inhibitors

• Dexlansoprazole
• Esomeprazole
• Lansoprazole
• Omeprazole
• Pantoprazole
• Rabeprazole

Selective Histamine Type 2 Receptor Antagonists or H2 Blockers

• Cimetidine
• Famotidine
• Nizatidine
• Ranitidine

• Dailymed label info on Cimetidine
• FDA Cimetidine

Cimetidine Resources
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