In Vivo Fates of Degradable Poly(β-Malic Acid) and of its Precursor,Malic Acid

Abstract

To determine whether degradation could influence the in vivo elimination pattern of poly(β-malic acid) in mice, radioactive urinary excretion and ¹⁴CO₂ expiration were studied after intravenous injection of ¹⁴C-radiolabeled poly(β-malic acid) and of its precursor, ¹⁴C-malate. The precursor administration led to rapid ¹⁴CO₂ exhalation, and only negligible urinary elimination. The reverse was observed for the polymer. It was concluded that: (i) the in vivo degradation of poly(β-malic acid) chains, if any during the 24-h period of the study, did not release detectable malate molecules, (ii) the large urinary excretion of poly(β-malic acid) was due to the molar masses being less than the renal filtration threshold, (iii) the degradation of the poly(β-malic acid) chains in blood was slow enough to allow the fraction with higher molar masses to enter the interstitial space of the tissues, and possibly cells.

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