Aug
1
Cimetidine
August 1, 2009 |
Generic Name
Cimetidine (sih-MET-ih-dene)
Brand
Tagamet Tagamet HB 91
Type of Drug Histamine H2 antagonist.
Prescribed For
Ulcers of the stomach and duodenum (upper intestine); also used for upset stomach, gastroesophageal reflux disease (GERD), benign stomach ulcer, bleeding in the stomach and duodenum, colorectal cancer, prevention of stress ulcer, hyperparathyroidism, fungal infections of the hair and scalp, herpes virus infection, excessive hairiness in women, chronic itching of unknown cause, skin reactions, warts, acetaminophen overdose, and other conditions characterized by the production of large amounts of gastric fluids. Cimetidine may be prescribed to stop the production of stomach acid during surgery.
General Information
Histamine H2 antagonists work by turning off the system that produces stomach acid and other secretions. Cimetidine is effective in treating the symptoms of ulcer and preventing complications of the disease, although an ulcer that does not respond to another histamine H2 antagonist will probably not respond to cimetidine. Histamine H2 antagonists differ only in their potency. Cimetidine is the least potent; 1000 mg are roughly equal to 300 mg of either nizatidine or ranitidine, or 40 mg of famotidine. These drugs are roughly equal in their ability to treat ulcer disease and their risk of side effects.
Cautions and Warnings
Do not take cimetidine if you are allergic or sensitive to any of its ingredients or any histamine H2 antagonist. Cimetidine has a mild antiandrogen effect, which probably causes the painful, swollen breasts that some people experience after taking this drug for a month or more.
People with kidney or liver disease should take cimetidine with caution because 1/3 of each dose is broken down in the liver and passes out of the body through the kidneys.
Do not self-treat with over-the-counter forms of cimetidine without the advice and supervision of your doctor.
The fact that symptalleviated by cimetidine does not dude the possibility of stomach cancer, which can have symptoms similar to other gastrointestinal (GI) disorders. Make sure your doctor screens for possible malignancy.
these symptoms stop 3-4 days after discontinuing the drug. Call your doctor if this happens to you.
Possible Side Effects
Serious side effects are uncommon.
♦ Most common: mild diarrhea, dizziness, rash, painful breast swelling, nausea and vomiting, headache, confusion, drowsiness, hallucinations, and impotence.
♦ Less common: liver inflammation, peeling or red and swollen rash, breathing difficulties, tingling in the hands or feet, delirious feelings, and oozing from the nipples.
✓ Rare: Cimetidine may affect white blood cells or blood platelets. Some symptoms of these effects are unusual bleeding or bruising, unusual tiredness, and weakness. Other rare side effects are inflammation of the pancreas, hair loss (reversible), abnormal heart rhythms, heart attack, muscle or joint pains, and drug reactions. Contact your doctor if you experience any side effect not listed above.
Drug Interactions
• Separate cimetidine from antacid doses by about 3 hours to avoid reducing cimetidine’s effectiveness. Other drugs that may reduce the absorption of cimetidine are metoclopramide and anticholinergic drugs, including trihexyphenidyl hydrochloride, oxybutynin, and benztropine mesylate.
• Cigarette smoking reverses the healing effect cimetidine has on ulcers.
• Cimetidine may increase the side effects of a variety of drugs, possibly leading to drug toxicity. These drugs include alcohol; aminophylline; oral antidiabetes drugs; benzodiazepine sedatives, except lorazepam, oxazepam, and temazepam; caffeine; calcium channel blockers; carbamweoine; carmustine; chloroquine; tkeCaiTAe; fluorouracil; labetalol; lidoQa« , Tneloprolol; metronidazole; moricizine; mexiletine; narcotic pain relievers; nifedipine; ondansetron; pentoxifylline; phenytoin; procainamide; propafenone; propranolol; quinine; quinidine; tacrine; theophylline drugs, except clyphylline: triamterene; tricyclic antidepressants; valproic acid; and warfarin (a blood-thinner).
• Drugs whose absorption may be decreased by cimetidine are iron, indomethacin, fluconazole, ketoconazole, and tetra-
cycline antibiotics.
• Enteric-coated tablets should not be taken with cimetidine. The change in stomach acidity causes the tablets to disin-
tegrate prematurely in the stomach.
• cimetidine may decrease the effects of digoxin and tocainide.
Food Interactions
None known.
Usual Dose
Adult: 400-800 mg at bedtime; 300 mg 4 times a day with meals and at bedtime; or 400 mg twice a day. To treat GERD-400 mg 4 times a day. Do not exceed 2400 mg a day. Users of Tagamet HB should not take more than 400 mg a day. Smaller doses may be as effective for seniors or those with impaired kidney function.
Overdosage
Little is known about the effects of cimetidine overdose, but victims may experience exaggerated side effects. Two deaths have occurred. Your local poison control center may advise giving ipecac syrup—available at any pharmacy—to induce vomiting and remove any drug remaining in the stomach. Victims who have definite symptoms should be taken to a hospital emergency room. ALWAYS bring the prescription bottle or container.
Special Information
Take cimetidine exactly as directed and follow your doctor’s instructions regarding diet and other treatment in order to get the maximum benefit from the drug.
Do not take the maximum dose continuously for more than 2 weeks without the consent and supervision of your doctor.
Cigarette smoking is associated with stomach ulcers and reduces cimetidine’s effectiveness.
Call your doctor at once if you develop any unusual side effects such as bleeding or bruisiiAg, tiredness, diarrhea, dizziness, rash, 131 NMbdinations. Black, tarry stools or vomiting material that resembles coffee grounds may indicate your ulcer is bleeding.
If you miss a dose of cimetidine, take it as soon as possible. If it is almost time for your next dose, skip the dose you forgot and continue with your regular schedule. Do not take a double dose.
Special Populations
Pregnancy/Breast-feeding: Animal studies reveal no damage to the fetus, although cimetidine does pass into the fetal blood. When this drug is considered crucial by your doctor, its potential benefits must be carefully weighed against its risks.
Large amounts of cimetidine pass into breast milk. Nursing mothers who must take this drug should use infant formula.
Seniors: Seniors may need less medication due to loss of kidney function and be more susceptible to side effects, especially confusion and other nervous system effects (see “Cautions and Warnings”).