Effect of Oral 688A (N-Phenoxyisopropyl-N-Benzyl-β-Chloroethylamine Hydrochloride) on Blood Pressure in Normotensive and Hypertensive Subjects. ∗

Summary and conclusions

1. The foregoing results indicate that 688A, a new adrenergic blocking agent, is an effective oral drug. It induces a fall in both supine and erect blood pressures in all subjects. The degree of the manometric effect depends on the dosage used and on the group of patients. The duration of the decrease in B.P. following a single dose is variable and usually lasts 3 to 5 hours. Symptomatic improvement occurred in 16 of 22 patients with hypertension. Improvement was noted in a few cases even in the absence of appreciable fall in B.P. As noted above, evaluation of symptomatic improvement may be difficult, since in a few cases the effects of placebo were equally good, for at least several weeks. Cold pressor tests showed that 688A in the dosage used, usually induced partial inhibition. It is possible that by its specific sympatholytic action 688A, besides its hypotensive effect, also prevents sudden rises in B.P. as indicated by the cold pressor tests. 2. Side effects of this drug were remarkably few and minor. Occasional drowsiness and sensation of fatigue were among the most disabling reactions noted in some patients. Proper dose adjustment seemed to be an important factor in preventing side effects. It should be noted that these side effects actually represent clinical criteria of adequate adrenergic blockade. Toxic symptoms such as nausea, vomiting and possibly fatigue were rarely encountered. Tolerance to the drug was noted in a few cases and may represent a shortcoming in a long—term treatment. 3. While individual responses to the drug were variable, the overall results in the entire group of patients indicate that 688A is effective in lowering B.P. and alleviating hypertensive symptoms. 4. These preliminary results obtained with 688A appear encouraging. The potentialities of this drug in arterial hypertension and peripheral vascular diseases are under further investigation. Detailed studies will be published elsewhere.