Lutetium-177

Lu-177 decays by a low-energy beta, so no single decay deposits much energy in the water around it. What makes it the heaviest sustained peroxide burden that actually reaches patients is the combination behind it: therapeutic vials are filled at gigabecquerel activity, and the 6.6-day half-life keeps that activity (and its radiolytic output) running across the entire usable life of the dose.

The physics is a product of three public numbers. Mean beta energy sets how much energy each decay deposits; the radiolytic yield (G) sets how many peroxide molecules that energy produces; and the half-life sets how long production continues. Lu-177 is unremarkable on the first two and long on the third, so its hydrogen-peroxide burden climbs steadily and then stays elevated for days: precisely the days the dose spends in QC release, transport, and the pharmacy before administration.

Published stability work on ¹⁷⁷Lu radiopharmaceuticals documents radiolytic degradation lowering radiochemical purity over storage; once purity drifts toward the release limit, a batch is shelf-life-restricted or scrapped. That documented loss is the clearest real-world evidence in the roster that in-vial radiolysis carries a commercial cost.

DuraRad lines the vial wall with a sol-gel coating carrying two immobilized enzymes: manganese superoxide dismutase, which converts superoxide into hydrogen peroxide and oxygen, and catalase, which decomposes that peroxide into water and oxygen. Radiolysis of the water generates reactive oxygen species throughout the fill, in every direction, and the superoxide and peroxide that diffuse to the wall are consumed there, so the coating behaves as a distributed sink that lowers their steady-state concentration in the vial. Because the enzymes are fixed in the coating rather than dissolved in the fill, they act as that sink without becoming a formulation additive. Clearing that superoxide and peroxide at the wall keeps their concentration low across Lu-177's multi-day shelf life and lowers the oxidative burden on the drug.

Of the isotopes in this roster, Lu-177 is the one this sink suits best. It decays by a low-energy beta with a 6.6-day half-life, so a gigabecquerel therapeutic fill produces peroxide slowly but continuously across the days a dose spends in QC release, transport, and the pharmacy before administration. Enzymatic clearance runs on a timescale of minutes, so against that slow, sustained production the coating completes many clearance cycles for every increment of peroxide the decay adds, and the model holds steady-state superoxide and peroxide well below the level an uncoated vial accumulates. The modeled suppression is large but not yet confirmed under radiation; the Q4 2026 radioactive validation at Washington University in St. Louis is designed to test it under continuous irradiation.