Radiat Res. 2003 Jul;160(1):103-9.  

Determination of Radical Yields in Solid-State Drugs as One Technique to
Identify Drugs that will Withstand Radiosterilization: Radioresistance of Beta
Blockers.

Engalytcheff A, Deridder V, Debuyst R, Tilquin B.

Laboratory of Chemical and Physicochemical Analysis of Drugs (CHAM), Universite
Catholique de Louvain, Brussels, Belgium.

Engalytcheff, A., Deridder, V., Debuyst, R. and Tilquin, B. Determination of
Radical Yields in Solid-State Drugs as One Technique to Identify Drugs that will
Withstand Radiosterilization: Radioresistance of Beta Blockers. Radiat. Res.
160, 103-109 (2003). This article describes a simple preliminary test to
determine whether a drug is sufficiently radioresistant to withstand
radiosterilization. The test is based on the electron spin resonance (ESR)
detection of radicals produced after irradiation of a solid-state drug, assuming
that these radicals are the precursors of the final products detected after
dissolution of the drug. A calibration curve has therefore been established by
measuring ESR spectra of l-alanine irradiated at different doses. The response
factor to quantify the radicals is the normalized double integration (DI) of the
whole first-derivative ESR spectrum. The curve gives the relationship between
the normalized DI and the number of radicals. Eight beta blockers have been
chosen and their radical yield determined. This is the first time that several
different drugs of the same pharmacological group have been studied and
compared. The results obtained are similar for seven of the eight beta blockers;
the mean G value (excepted for nadolol) is 3 x 10(-9) mol/J. This means that
beta blockers are radioresistant. The two most radiosensitive drugs (nadolol and
esmolol hydrochloride) were also studied by high-performance liquid
chromatography (HPLC). No significant loss of the active compound was detected,
which confirms this radioresistant property. Moreover, no change in color or
smell was observed. Using ESR and HPLC, beta blockers were identified as
potential candidates for radiosterilization.

PMID: 12816529 [PubMed - in process]