May 2008
Volume 49, Issue 13
ARVO Annual Meeting Abstract  |   May 2008
Evaluation of Ocular and Systemic Safety of Calcium Formate, a New Calcium Supplement
Author Affiliations & Notes
  • M. M. Altaweel
    Ophthalmology & Visual Science, Univ of Wisconsin-Madison, Madison, Wisconsin
  • J. VerHoeve
    Ophthalmology & Visual Science, Univ of Wisconsin-Madison, Madison, Wisconsin
  • J. Eells
    Health Science, Univ of Wisconsin-Milwaukee, Milwaukee, Wisconsin
  • R. Hanzlik
    Department of Medicinal Chemistry, University of Kansas, Lawrence, Kansas
  • Footnotes
    Commercial Relationships  M.M. Altaweel, Nephrotec, F; J. VerHoeve, Nephrotec, F; J. Eells, Nephrotec, F; R. Hanzlik, Nephrotec, C.
  • Footnotes
    Support  Nephrotec
Investigative Ophthalmology & Visual Science May 2008, Vol.49, 5217. doi:
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      M. M. Altaweel, J. VerHoeve, J. Eells, R. Hanzlik; Evaluation of Ocular and Systemic Safety of Calcium Formate, a New Calcium Supplement. Invest. Ophthalmol. Vis. Sci. 2008;49(13):5217. doi:

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      © ARVO (1962-2015); The Authors (2016-present)

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Purpose: : To evaluate the ocular and systemic safety of calcium formate, a potential dietary calcium supplement for the prevention and management of osteoporosis, and to determine whether formate accumulates in the serum with repeated dosing.Background: Although formate is an endogenous product of metabolism, extremely high serum concentrations have been associated with toxicity in the setting of methanol overdose.

Methods: : Calcium formate 1300 mg was ingested three times a day for 14 days by twelve healthy women. Baseline and follow-up evaluation included physical and ocular examination, extensive laboratory testing for major organ function, serum determination for calcium and formate levels at peak and trough, ETDRS visual acuity, color vision, masked grading of color fundus photographs, automated visual fields, visual evoked potential, full field electroretinogram, pattern ERG, and multifocal ERG.

Results: : There was no evidence of toxicity with calcium formate ingestion. All examinations, laboratory tests, and objective visual function testing remained normal and unchanged throughout the study. There was no evidence of deleterious effect on optic nerve or retinal function as evaluated with electrophysiology. Three subjects had mild transient symptoms attributable to any calcium formulation. The mean baseline serum level of formate was 0.572 +/- 0.06 mM (95% CI 0.532 - 0.613). Both peak serum levels through the study and the final mean serum level of formate did not differ significantly from baseline. The final concentration at 2 weeks was 0.582 +/- 0.091 mM (95%CI 0.521 - 0.642). Formate did not accumulate in the serum.

Conclusions: : Calcium formate is highly bioavailable and is well tolerated in moderately high doses. The formate component did not accumulate with repeated dosing, remaining at basal levels. Systemic and ocular safety were demonstrated with thorough testing. Calcium formate may be a good choice for calcium supplementation in the prevention and management of osteoporosis.

Clinical Trial: : NCT00204893

Keywords: calcium • electrophysiology: clinical • clinical (human) or epidemiologic studies: outcomes/complications 

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