SOME PHARMACOLOGIC PROPERTIES OF LEVO- AND DEXTRO-NORDEFRIN

¹ Sterling-Winthrop Research Institute, Rensselaer, N. Y.

1. On dogs anesthetized with pentobarbital, levo-nordefrin was found 100 to 200 times more active than the dextro-isomer in raising the blood pressure. Epinephrine was 2 to 2.5 times more active than levo-nordefrin. In approximately equipressor doses, levo-nordefrin produced a somewhat greater increase in heart rate than epinephrine.

2. In equipressor doses, epinephrine was considerably more active than levo-nordefrin in stimulating the retractor penis whose motility was recorded simultaneously with the blood pressure. When equipressor doses of levo- and dextro-nordefrin were compared, dextro-nordefrin produced greater contractions of the retractor penis.

3. On the nonpregnant rat uterus in vitro, epinephrine was found 15 times more inhibitory than levo-nordefrin and the latter approximately 5,000 times more active than the dextro-isomer.

4. The intravenous LD₅₀ ± S.E. of levo-nordefrin in white mice was 12.6 ± 2.7 mg./Kg. This compound was found 10 times more toxic than the dextro-isomer, and approximately one fifth as toxic as epinephrine.

5. Levo-nordefrin prolongs significantly the duration of local anesthesia. At a concentration of 1:20,000, duration was doubled when compared to the same solution without a vasoconstrictor. At a level of 1:10,000, the duration was increased an additional 30 per cent.

6. When levo-nordefrin 1:20,000 was compared with racemic nordefrin 1:10,000 in a solution of Ravocaine-Novocain, the duration was slightly longer with the racemic compound. This difference, however, is probably not of sufficient magnitude to be considered significant.