Drug Advice: CIMETIDINE, RANITIDINE, FAMOTIDINE

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Category: Histamine H2-receptor antagonists; antiulcer agents, gastric secretion inhibitors.

Information for pharmacists:

1. These relatively new drugs may be preferred to other antiulcer agents because of their convenience and lack of effect on gastrointestinal motility.

2.Cimetidine, Ranitidine or Famotidine may be administered to treat peptic ulcers or hypersecretory states.

(a) Cimetidine, the first H2-receptor antagonist approved for clinical use, reduces gastric acid secretion by about 50% (at a total daily dosage of 1000mg).

(b) Ranitidine, a more potent drug, causes a 70% reduction in gastric acid secretion (at a total daily dosage of 300mg).

(c) Famotidine is the most patent H2-receptor antagonist. After a 40mg dose, mean nocturnal gastric acid secretion is reduced by
94% for up to 1 0 hours.

3. Significant interactions:

(a)Cimetidine may interfere with the metabolism of such drugs as phenytoin, theophylline, phenobarbital, lidocaine, warfarin, imipramine, diazepam and propranolol.

(b)Antacids impair absorption of cimetidine and ranitidine and should be given 1 hour apart from these drugs.

(c)Cimetidine inhibits the excretion of procainamide.

(d)Cimetidine interferes with absorption or excretion of ketoconazole, nifedipine and procainamide.

Information for the patient:

I.These drugs reduce gastric secretions and heal ulcers.

2.If you are taking antacids, do not take them within 1hour of cimetidine, ranitidine or famotidine.

3.You must comply with ful1 course of therapy.

4. If you miss a dose,

?Take it as soon as possible.
?Do not lake if almost time or next dose.
?Do not lake if almost time or next dose.

5.Keep out of reach of children.

6.Concurrent administration of famotidine or ranitidine with enteric coated tablets may cause the enteric coating to dissolve too rapidly due to an increase in gastric pH.

7.If ranitidine or famotidine or cimetidine and ketoconazole are to be taken together, they should be taken at least 2 hours after ketoconazole.

8. Avoid use of foods, drinks or other medication that may cause gastrointestinal irritation.

Reference:
Advice for the patient: Drug information in lay language; USP DI; 1995,15th edition; pg nos: 925-929.

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Santosh kumar. JH's picture

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Comments

Prof. J. Vijaya Ratna's picture

Santosh You have done a good job by giving a comparative assessment of three antacids. You may also give, by consulting CIMs, some brand names and a comparative assessment of their prices. You may compare the prices of these medicines with the price of omeprazole also as it is a drug with similar action. Vijaya Ratna
Santosh kumar. JH's picture

Dear Ma'am

Source: CIIMS: July- October 2009 Edition.

Analysis of the prices:

I had provided the maximum, median and least price of the available brands in CIIMS there was a marketed variation if we compare the highest and lowest prices of rantidine, famotidine and omeprazole it was almost double.

P.V.ABHIGNA's picture

Santosh, Good work done bye you.Why is famotidine not given through IM or IV? Secondly Cimetidine is a drug generally not used these days because of its side effects may be because of its modest affinity towards androgen receptors....Can u please make these things clear. Regards,

ABHIGNA.P.V.

Santosh kumar. JH's picture

Famotidine is generally given in tablet form since the site of action is on the parietal cells which is possible with only enteral route so it is not recommended as I.V or I. M although its has poor bioavailability. Cemitidine is having modest side effects although it is not having a steroid nucleus to bind with androgenic receptors at some specific sites which was unclear it is found to compete with tritiated dihydrotestosterone-binding sites in mouse kidney in one study. [1] Reference; 1. http://jcem.endojournals.org/cgi/content/abstract/48/2/189 [accessed on 4th September 2010]
Niklesh Rao V's picture

Dear santosh, Can you please explain the reason behind this statement, "7.If ranitidine or famotidine or cimetidine and ketoconazole are to be taken together, they should be taken at least 2 hours after ketoconazole."

Regards, Niklesh Rao V