EVALUATION OF NONINVASIVE TECHNIQUES TO ASSESS VASOCONSTRICTION IN HEALTHY-VOLUNTEERS USING METHOXAMINE AS A PROBE DRUG

Non-invasive methods for assessment of the vascular effects of antimig raine drugs were evaluated with respect to their utility, variability and sensitivity in a double-blind, placebo-controlled, three-period cr ossover study in six healthy volunteers using an intravenous vasoconst rictor, methoxamine, as a probe drug. Changes in the internal diameter of the brachial and radial arteries were measured using ultrasound wh ich had low between-day and within-day coefficients of variation. Peak systolic velocity (PSV), time-averaged velocity (TAV), total flow, re sistance (RI) and pulsatility indices (PI) were measured by Doppler fr om one arterial wave form. Whilst PSV and TAV increased with methoxami ne, because of bradycardia, changes in PI and RI were difficult to int erpret. An automatic oscillometric cuff, a mercury-in-silastic strain gauge method and the ''Finapres'', finger arterial blood pressure moni tor were used to follow changes in systolic blood pressure (SBP). The strain gauge technique underestimated arm SBP compared to the oscillom etric method but clearly showed drug-related increases whilst the Fina pres did not reflect changes in blood pressure detected by the other m ethods.