Effect of Analeptic Drugs on the Somnifacient Effect of Seconal and Antihistaminics as Measured by the Flicker Fusion Threshold

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Abstract
Seconal in oral doses of 96 mg. produced a depression of the FFT (flicker fusion threshold) in all 15 subjects tested. Drowsiness was noted in all. Benadryl administered intramusc. in 10- or 15-mg. doses depressed the FFT in 16 of 20 subjects. Of these 16 subjects only 3 noted drowsiness. Benadryl administered intramusc. in 10- or 15-mg. doses depressed the FFT in all 10 subjects with bronchial asthma. Drowsiness was noted in all. There was a significant depression of the FFT with Furdylamine, Thenylpyramine and the various combinations of these drugs with acetophenetidin, acetyl-p-aminophenol and caffeine. There was a depression of the mean FFT in 55 of the total 60 detns. There was a significant difference between the depression produced by each of the drugs and drug combinations tested. Of the total 24 detns. with 12 subjects given 30 mg. caffeine orally, there was an impairment or decrease in the FFT in 22 detns. The sympathomimetic drugs, Dexedrine and Benzedrine, definitely increased the FFT, and the effect is proportional to the dosage within the range studied. Nine of the 12 subjects tested with Eskel showed a depression of the FFT. Caffeine does not counteract the depressive effect of Thenylpyramine or Furdylamine on the FFT. Dexedrine, 5 mg., is adequate to prevent depression of the FFT when used in combination with either 50 mg. or 100 mg. of Thenylpyramine. Although 5 mg. of Benzedrine is also adequate to prevent a significant depression of the FFT with 50 or 100 mg. of Thenylpyramine, to produce the same effect as Dexedrine, 5 mg. of Benzedrine is required to counteract the depression of the FFT caused by each dose of 50 mg. Thenylpyramine. The depressive effects of 96 mg. of Seconal and 10 to 15 mg. of Benadryl appear to be comparable as measured by depression of the FFT, although the incidence of drowsiness occurred with greater frequency among subjects receiving Seconal. The FFT would appear to be a sensitive and reliable method for objectively detecting the less obvious depressing and stimulating effects of antihistaminics, barbiturates, and sympathomimetic drugs on the nervous system.