Determinants of the pressor effect of phenylpropanolamine in healthy subjects
G. L. Blackburn, J. P. Morgan, P. T. Lavin, R. Noble, F. R. Funderburk and N. Istfan
Department of Surgery, Harvard Medical School, New England Deaconess Hospital, Boston, MA 02215.
Phenylpropanolamine (PPA) is frequently used in over-the-counter diet aids
and cold medicines, In view of concern about the safety of this
sympathomimetic agent, we undertook a double-blind, multicenter clinical
trial to determine the factors that influence the pressor effect of
short-term oral administration of PPA in healthy individuals. Eight hundred
eighty-one healthy individuals in four categories of body weight were
randomized to receive placebo capsules three times per day (n = 286), a
75-mg sustained-release PPA hydrochloride preparation once per day (n =
296) followed by two doses of placebo capsules, or a 25-mg
immediate-release PPA hydrochloride preparation three times per day (n =
299). The median age of the study population was 28 years, 56% were men,
73% were white, and 47% were in excess of 30% above their ideal body
weight. Measurements of pulse rate and supine and standing blood pressure
were made 11 times during the day of PPA administration. A statistically
significant but clinically unimportant pressor effect for the short-term
administration of PPA was observed. The effect occurred in the first 6
hours after administration and was greater in the sustained-release group.
Significant independent determinants of the pressor effect of PPA were
baseline diastolic blood pressure, baseline body weight, and treatment.
