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[Inhibition of the heparin effect by nitroglycerin]
L Pizzulli1, J Nitsch, B Lüderitz
1Medizinische Universitätsklinik, Innere Medizin-Kardiologie, Bonn.
The interaction of intravenous (i.v.) nitroglycerin (glyceryl trinitrate) on the anticoagulant effect of heparin was studied in 27 patients. The heparin dose was adjusted (800-1400 IU/h) to achieve partial thromboplastin time (PTT) of more than 100 s (130 +/- 28 s). While the heparin infusion was continued at the same dosage, the patients received 2-5 mg/h nitroglycerin i.v. (Perlinganit without propylene glycol [15 patients] or Gilustenon with propylene glycol [12 patients]). During combined heparin and nitroglycerin (NG) administration PTT decreased significantly (60 +/- 23 s; P less than 0.01). After withdrawal of NG, PTT increased to the initial levels (126 +/- 30 s). The drug interaction was seen in both groups--with or without propylene glycol. In nine of the 27 patients plasma heparin levels were measured; they remained unchanged during NG administration. The results indicate that i.v. NG induces heparin resistance. After NG is withdrawn, a rebound increase in PTT may occur. Adequate monitoring of PTT and heparin dosage adjustment are thus required during combined heparin and NG administration.
The interaction of intravenous (i.v.) nitroglycerin (glyceryl trinitrate) on the anticoagulant effect of heparin was studied in 27 patients. The heparin dose was adjusted (800-1400 IU/h) to achieve partial thromboplastin time (PTT) of more than 100 s (130 +/- 28 s). While the heparin infusion was continued at the same dosage, the patients received 2-5 mg/h nitroglycerin i.v. (Perlinganit without propylene glycol [15 patients] or Gilustenon with propylene glycol [12 patients]). During combined heparin and nitroglycerin (NG) administration PTT decreased significantly (60 +/- 23 s; P less than 0.01). After withdrawal of NG, PTT increased to the initial levels (126 +/- 30 s). The drug interaction was seen in both groups--with or without propylene glycol. In nine of the 27 patients plasma heparin levels were measured; they remained unchanged during NG administration. The results indicate that i.v. NG induces heparin resistance. After NG is withdrawn, a rebound increase in PTT may occur. Adequate monitoring of PTT and heparin dosage adjustment are thus required during combined heparin and NG administration.