Effects of the non-selective phosphodiesterase inhibitor pentoxifylline onregional cerebral blood flow and large arteries in healthy subjects

The vasodilating properties of the non-selective phosphodiesterase (PDE) in hibitor pentoxifylline were evaluated. Pentoxifylline has been reported to increase cerebral blood flow (CBF) and improve recovery rate of stroke pati ents. Whether these results are due to a dilating effect on arteries or to other mechanisms is not clear. In the present double-blind crossover study, 10 healthy subjects received pentoxifylline 300 mg or placebo intravenousl y on separate days. Blood flow velocity in the middle cerebral artery (V-mc a) was recorded by transcranial Doppler and rCBF was measured using (133)Xe non-inhalation SPECT. High-frequency ultrasound was used for measurements o f temporal and radial artery diameter. Cyclic guanosine monophosphate (cGMP ) and cyclic adenosine monophosphate (cAMP) concentrations were assessed in plasma. Except for increased heart rate (P < 0.05), systolic blood pressur e (P < 0.05) and plasma cAMP (P < 0.001), no significant differences in CBF , rCBF(mca) or plasma cGMP were seen between placebo and pentoxifylline inf usion. During pentoxifylline infusion, V-mca decreased 7.2% (SD 12.0; P < 0 .05) and temporal artery diameter increased 9.0% (SD 7.0; P < 0.001), sugge sting minor dilatation of the large arteries. However, this change was not significantly different from placebo. In conclusion, pentoxifylline 300 mg had no effect on rCBF. A possible minor dilatation of the middle cerebral a rtery and the temporal artery cannot be excluded. Any potential clinical ef fect of pentoxifylline is most likely mediated through non-vascular mechani sms.