Iron preparations modified-release

Many patients prefer to have a different type of iron preparation to ferrous sulphate tablets - they find they cause them fewer side-effects. The reason for this is generally that the product they prefer either contains less iron to start with or is a modified-release preparation. 

Modified-release preparations release iron gradually so less iron is present in the gastrointestinal tract at any one time. However, because they are modified-release, these preparations are likely to carry the iron past the first part of the duodenum into an area of the gut where iron absorption may be poor. The low incidence of side-effects may reflect the small amounts of iron available for absorption under these conditions and so the preparations have no therapeutic advantage and should not be used. 

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