[Strain-gauge plethysmographic measurement of the systemic bioavailability of oral nitroglycerin in liver cirrhosis].

7 cirrhotic (M = 3, F = 4, mean age 55, range 35-74) and 7 healthy subjects (M = 6, F = 1, mean age 24, range 23-40) were studied. 2.5mg% nitroglycerin were administered per os. This drug is quite completely metabolized in its first pass through the liver (first pass effect). Peripheric vascular effect of nitroglycerin was evaluated by venous occlusion strain-gauge plethysmography, ECG-coupled (Rest Flow measurement RF, in ml/min/100 ml). No statistically significant differences were found between pre-drug RF in the two groups and between pre and post-drug measurements in healthy subjects. Post-drug RF decreased in cirrhotic subjects when compared either to pre-drug values or to post-drug values in normal subjects (statistically significant after the third minute, p ranging less than 0.05 and less than 0.001). The different peripheric vascular effect found in the two groups was considered as a consequence of the increased drug bioavailability in cirrhotics, caused by portosystemic shunts.