EFFECTS OF NONIONIC MONOMERIC AND DIMERIC CONTRAST-MEDIA ON THE TWITCHING REACTION OF THE RAT - IMPORTANCE OF OSMOLALITY AND ELECTROLYTE CONTENT

RATIONALE AND OBJECTIVES. The authors established a rat model of the t witching reaction to contrast media in striated muscle and investigate d the influence of nonionic contrast medium on the twitching reaction regarding the nonionic dimer iodixanol compared with the monomer iohex ol and the dimer iotrolan, The authors also studied the influences fro m the electrolyte additions of iodixanol. METHODS. The interval from s tart of contrast medium injection to start of head movement was compar ed for iohexol (140 and 350 mg iodine/mL), iodixanol (150 and 320 mg i odine/mL), and iotrolan (300 mg iodine/mL), Comparison was made with m annitol and mannitol containing the same electrolyte concentrations as iodixanol(150 and 320 mg iodine/mL). RESULTS. No differences in laten cy period were found between iohexol 140 mg iodine/mL (isotonic) and 3 50 mg iodine/mL (880 mOsm/kg). Iodixanol caused a lesser effect on the twitching reaction than the iohexol solutions and iotrolan, When the electrolytes of iodixanol were added to mannitol(300 mOsm/kg), there w as a later onset of the twitching reaction than with electrolyte-free mannitol. CONCLUSIONS. Differences in latency period caused by a chang e in osmolality were not found, The interval for a twitching reaction was longer with iodixanol than with iohexol, iotrolan, and iso-osmolar mannitol, The weak effect of the iodixanol solution was probably part ially caused by the electrolyte content.