Cimetidine

About Cimetidine

Cimetidine blocks histamine at the H2 receptors of the stomach’s acid-making cells, lowering both daytime and nighttime acid. The prescription label covers short-term treatment of an active duodenal ulcer and maintenance at a lower dose once it heals, short-term treatment of a benign stomach ulcer, erosive esophagitis from reflux disease diagnosed by endoscopy, and conditions that make too much acid, such as Zollinger-Ellison syndrome. For a duodenal ulcer the usual adult dose is 800 mg at bedtime, continued for four to six weeks unless endoscopy shows healing, then 400 mg at bedtime for maintenance; erosive esophagitis is treated with 1,600 mg a day in divided doses for 12 weeks, and doses are spaced further apart when kidney function is severely reduced. The over-the-counter 200 mg tablet is for heartburn: one tablet, up to two in 24 hours, for no more than 14 days without a doctor’s advice; its use under age 12 has not been established.

There is no boxed warning, and the only contraindication is an allergy to cimetidine. Headache, dizziness, sleepiness and mild diarrhea are among the reported side effects. Breast enlargement in men has occurred with treatment lasting a month or longer, and reversible impotence has been reported in people with acid-hypersecretion disorders taking it for at least a year, particularly at high doses. Reversible confusion has been seen, mostly in severely ill people, with age 50 or older and liver or kidney disease as contributing factors; when the drug was stopped, it usually cleared within three to four days. Rises in liver enzymes, and rarely drops in white blood cells or platelets, have been reported. Relief of symptoms does not rule out stomach cancer, and anyone with kidney or liver disease should ask a doctor before using the over-the-counter tablets.

What sets cimetidine apart is its interactions. Through an effect on liver enzyme systems it slows the breakdown of warfarin-type blood thinners, phenytoin, propranolol, nifedipine, chlordiazepoxide, diazepam, certain tricyclic antidepressants, lidocaine, theophylline and metronidazole, raising their blood levels. With warfarin the label calls for close monitoring of prothrombin time and possible dose changes, and harmful effects have been reported with phenytoin, lidocaine and theophylline. Because it changes stomach acidity, ketoconazole should be taken at least two hours before it. Cimetidine passes into breast milk, and the label advises against nursing while taking it; in pregnancy it is used only if clearly needed, and it is not recommended under age 16 unless the prescriber judges that the benefits outweigh the risks.

Taking Cimetidine

How to take it

Prescription doses are usually taken with meals or at bedtime, as prescribed. For heartburn, take one over-the-counter tablet with a glass of water, or up to 30 minutes before food or drink that brings it on, and no more than two tablets in 24 hours. Measure the oral solution with a dosing syringe or dose-measuring device, not a kitchen spoon.

If you miss a dose

Take it as soon as you can, but skip the missed dose if it is almost time for the next one. Do not take two doses at one time.

Storage

At room temperature, away from moisture, heat and light.

Interactions to know about

It can raise blood levels of warfarin, phenytoin, theophylline, propranolol, nifedipine, lidocaine, diazepam, chlordiazepoxide, metronidazole and some tricyclic antidepressants, so these may need closer monitoring or a dose change. Take ketoconazole at least two hours before cimetidine. Check with the prescriber before adding another acid reducer or an antacid.

This summarizes the official prescribing information. Your prescriber’s and pharmacist’s instructions, and the leaflet that comes with your medicine, take priority.

Why the cash price for Cimetidine differs from pharmacy to pharmacy

Prescription cimetidine is an old generic, but it is not on every pharmacy’s flat-price list, and a pharmacy that rarely fills it may order it in and price it as a slow-moving item, so quotes for the same tablets can differ. The oral solution is a separate product, priced by the bottle and quoted on its own terms.

How the dose is written matters as well. An 800 mg bedtime dose is one tablet, while the same dose written as 400 mg tablets is two, and the 200 mg tablet sold over the counter is priced as a retail product and labeled only for heartburn, not for treating an ulcer or erosive esophagitis.

Ways to pay less for Cimetidine without insurance

• Ask the prescriber to write each dose in the fewest tablets, such as one 800 mg tablet at bedtime rather than two 400 mg tablets.
• Ask whether cimetidine is on the pharmacy’s flat-price generic list, and compare more than one pharmacy.
• For maintenance treatment, ask for a ninety-day supply once the plan is settled.
• Ask the prescriber whether another acid reducer, such as famotidine, would suit you.
• Upload the prescription to Script Unlock so licensed pharmacies can quote their cash price. You pay the pharmacy directly.

Questions to ask your pharmacist about Cimetidine

1. 1.Do any of my medicines, such as warfarin, phenytoin or theophylline, interact with cimetidine?
2. 2.Should I take my dose with meals or at bedtime?
3. 3.How long can I use the over-the-counter tablets before I see my doctor?
4. 4.Does my kidney or liver disease change my dose?

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