Enteric-coated iron

Gastric acid and ascorbic acid facilitate the absorption of iron. Therefore, bioavailability of iron ingested with food is considerably decreased and also enteric-coated iron preparations are absorbed to a lesser extend. Fixed combinations with ascorbic acid increase the absorption of iron by at least 30%. However such increased uptake seems to have little advantage over a modest increase of dose. 

Oral iron therapy with soluble ferrous iron salts, which are not enteric coated and not slow- or sustained-release, is recommended at a daily dosage of200 mg elemental iron in two or three divided doses (Table 33-3). 

Substances which form masses Aspirin, iron, lithium, enteric-coated tablets, meprobamate. 

Rudinskas L, Paton TW, Walker SE, et al. Poor clinical response to enteric- 57. coated iron preparations. Can Med Assoc J 1989 141 565-566. 

The tablets should not be crushed they are enteric-coated. If the client cannot swallow tablets, liquid iron preparations are available. 

In health care facilities, ipecac is rarely indicated but may find occasional use In patients with recent ingestions involving substances poorly adsorbed by activated charcoal (eg, iron, lithium, potassium, and sodium) or sustained-release or enteric-coated tablets. 

An enteric-coated delivery system of MPA was developed with the aim that it would minimize gastrointestinal side effects [55]. Myfortic, approved by the FDA in 2004, is an enteric formulation of mycophenolate sodium (EC-MPS), which releases the active MPA moiety. The enteric coating of the tablet consists of the polymer, hypromellose phthalate combined with titanium dioxide, iron oxide yellow, and indigotine (180 mg tablet) or iron oxide red (360 mg tablet) [56]. Hypromellose phthalate is a monoph-thalic acid ester of hydroxypropyl methylcellulose which dissolves at pH 5-5.5, thereby affording delivery of MPA to the small intestine rather than the stomach. 

The modification improves performance and is interesting in connection with x-ray emission spectrography (Chapters 7, 8, and 9). It consists in measuring the intensity of tin Ka relative to that of scattered x-rays entering the detector from an analyzing crystal set for the reflection of x-rays 2.2 A in wavelength. As the tin coating becomes thicker, increased attenuation of the x-rays scattered by the iron cause s the intensity ratio to increase more rapidly than does the intensity of tin Ka. Table 6-3 contains performance data for the Quantrol on Method II (modified). The instrument can also be set up to use industrially a modification of Method III. 

The function of all ferritin molecules is to store iron. However, the mechanisms by which iron enters the core or is released from the core 1ji vivo is poorly understood. Experimentally, Fe(II), but not Fe(III), mixed with ferritin protein coats forms normal iron cores. Moreover, reductants such as thloglycollate or reduced flavins can reverse the process of core formation and release Fe(II) from the core. Since such reductants occur in vivo, reduction of ferritin cores may also occur vivo. 

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