Absorption and side-effects after peroral administration of sustained release iron tablets. Ferro-Retard compared with Ferronicum and Duroferon Duretter

Ferrous sulfate supplementation causes significant gastrointestinal side-effects in adults: a systematic review and meta-analysis

Background

The tolerability of oral iron supplementation for the treatment of iron deficiency anemia is disputed.

Objective

Our aim was to quantify the odds of GI side-effects in adults related to current gold standard oral iron therapy, namely ferrous sulfate.

Methods

Systematic review and meta-analysis of randomized controlled trials (RCTs) evaluating GI side-effects that included ferrous sulfate and a comparator that was either placebo or intravenous (IV) iron. Random effects meta-analysis modelling was undertaken and study heterogeneity was summarised using I² statistics.

Results

Forty three trials comprising 6831 adult participants were included. Twenty trials (n = 3168) had a placebo arm and twenty three trials (n = 3663) had an active comparator arm of IV iron. Ferrous sulfate supplementation significantly increased risk of GI side-effects versus placebo with an odds ratio (OR) of 2.32 [95% CI 1.74–3.08, p<0.0001, I² = 53.6%] and versus IV iron with an OR of 3.05 [95% CI 2.07-4.48, p<0.0001, I² = 41.6%]. Subgroup analysis in IBD patients showed a similar effect versus IV iron (OR = 3.14, 95% CI 1.34-7.36, p = 0.008, I² = 0%). Likewise, subgroup analysis of pooled data from 7 RCTs in pregnant women (n = 1028) showed a statistically significant increased risk of GI side-effects for ferrous sulfate although there was marked heterogeneity in the data (OR = 3.33, 95% CI 1.19-9.28, p = 0.02, I² = 66.1%). Meta-regression did not provide significant evidence of an association between the study OR and the iron dose.

Conclusions

Our meta-analysis confirms that ferrous sulfate is associated with a significant increase in gastrointestinal-specific side-effects but does not find a relationship with dose.

Tolerability of different oral iron supplements: a systematic review

OBJECTIVE

A systematic review was conducted to analyze the tolerability of several oral iron supplements based on data obtained in available publications and to report the incidence of adverse effects (AEs) for each supplement both overall and gastrointestinal.

METHODS

Electronic databases - Medline, the Cochrane Library, and Embase were searched for studies published up to January 2009. Clinical or observational studies reporting data on the tolerability of oral iron supplements were included. Results were described statistically and a quasi-binomial logistic regression model was developed to evaluate and compare the tolerability of the supplements studied.

RESULTS

For this review 111 studies were included, with data on 10,695 patients. Ferrous sulfate with mucoproteose had the lowest incidence of AEs (4.1% for overall AEs, 3.7% for gastrointestinal AEs [GAEs]) and was used as the reference supplement in the regression model. Incidence rates of overall AEs for the other supplements were 7.3% for iron protein succinylate [GAEs: 7%; OR for AE compared to the reference supplement, 1.96], 23.5% for ferrous glycine sulfate [GAEs: 18.5%; OR: 5.90], 30.9% for ferrous gluconate [GAEs: 29.9%; OR: 11.06], 32.3% for ferrous sulfate without mucoproteose [GAEs: 30.2%; OR: 11.21], and 47.0% for ferrous fumarate [GAEs: 43.4%; OR: 19.87]. The differences in incidence of AEs between extended-release ferrous sulfate with mucoproteose and all other supplements except iron protein succinylate were statistically significant at p < 0.001. These findings are subject to some limitations as the designs and methodologies of the studies included show heterogeneity among them that has partially been counteracted by the large sample size provided by the substantial number of trials, which is considered a strength in tolerability studies.

CONCLUSION

Extended-release ferrous sulfate with mucoproteose appears to be the best tolerated of the different oral iron supplements evaluated.

Anaemia in elderly patients. Incidence and causes of low haemoglobin concentration in a city general practice

Haemoglobin concentration was determined in all patients (530) over 70 years of age in a general practice in Oslo during an eight month period. 72 had anaemia and were investigated further. Iron deficiency was found in 13 patients and was most often caused by gastrointestinal blood loss. Chronic diseases, particularly chronic infections and rheumatoid arthritis, were responsible for anaemia in 34 patients. Renal failure caused anaemia in 14 patients. In 10 patients we found no explanation for the anaemia. Nine patients with a previously undiscovered disease were found, six of whom could be offered some kind of treatment. We conclude that anaemia in elderly patients in general practice is often caused by chronic diseases. The main cause of iron deficiency is blood loss, and routine prescription of iron is not justified in this age group. The therapeutic benefit from routine measurement of haemoglobin concentration is small and the test should be used selectively.