Ferrous sulfate Cimetidine

ShibaK, Kusajimal Momo K. The effects of aluminium hydroxide, cimetidine, ferrous sulfate, green tea andmilk on pharmacckinetics of gatifloxacin in healthy humans. J Antimicrob Chemoiier ( 999) 44 (Suppl A), 141. 

Apart from a brief and unconfirmed report alleging that cimeti-dine reduced the response to ferrous sulfate in three patients, there appears to be no other evidence that H2-receptor antagonists reduce the absorption of iron to a clinically relevant extent Iron causes only a small and clinically irrelevant reduction in the serum levels of cimetidine and famotidine. 

A brief report describes 3 patients taking cimetidine 1 g and ferrous sulfate 600 mg daily whose ulcers healed after 2 months, but their anaemia and altered iron metabolism persisted. When the cimetidine was reduced to 400 mg daily, but with the same dose of iron, the blood picture resolved satisfactorily within a month. The author of the report attributed this response to the cimetidine-induced rise in gastric pH, which reduced the absorption of the iron. However, this suggested mechanism was subsequently disputed, as medicinal iron is already in the most absorbable form, Fe, and so does not need an acidic environment to aid absorption. A study in patients with iron deficiency, or iron-deficiency anaemia, found that the eoneurrent use of famotidine, nizatidine, or ranitidine, did not affeet their response to 2.4 g of iron succinyl-protein complex (equivalent to 60 mg of iron twice daily). No special precautions would seem necessary on concurrent use. 

In a series of 3 studies, healthy subjects were given a 300-mg tablet of cimetidine with either a 300-mg tablet of ferrous sulfate or 300 mg of ferrous sulfate in solution. The reductions in the AUC and the maximum serum levels of the cimetidine were small (less than 16%). In the third experiment they were given famotidine 40 mg with a 300-mg tablet of ferrous sulfate. Again, the AUC and maximum serum level reductions were also very small (10% or less). These small reductions are almost certainly due to the formation of a weak complex between the iron and these H2-receptor antagonists." An in vitro study with ranitidine found that, while it also binds with iron, it forms a very weak complex, and is less likely to bind than cimetidine or famotidine." It was concluded that no clinically relevant interaction occurs between ferrous sulfate and any of these H2-receptor antagonists." ... 

Partlow ES, Campbell NRC, Chan SC, Pap KM, Granberg K, Hasinoff BB. Ferrous sulfate does not reduce serum levels of famotidine or cimetidine after concurrent ingestion. Clin Pharmacol Ther (1996) 59, 389-93,... 

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See also in sourсe #XX -- [ ]

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