Lipolytic effect of low-molecular-weight-heparin (Fragmin®) and heparin/dihydroergotamine in thromboprophylactic doses during total hip replacement

Eighteen patients admitted for implantation of a primary hip prosthesis were randomized to one of the following thromboprophylactic regimens: (1) dextran 500 ml 12 h-1 on the day of surgery and 500 ml on days 1, 3, and 5 postoperatively, (2) heparin 5000 IU and dihydroergotamine 0.5 mg 8 h-1, or (3) Fragmin (Kabi-Pharmacia, Sweden) 2500 IU 12 h-1 on the day of surgery and 5000 IU 24 h-1 throughout the observation period. Fragmin is a low molecular-weight heparin which has proven both efficient and safe as a thromboprophylactic drug. The purpose of the study was to elucidate whether Fragmin had a lower lipolytic (fatty acid-mobilizing) effect than standard heparin. The plasma level of lipoprotein lipase (LPL) was increased on the first post-operative day both in the heparin/dihydroergotamine (preoperative 217 +/- 79 microU ml-1 vs. 1289 +/- 318, n = 6, p < 0.05) and the Fragmin-groups (136 +/- 16 vs. 668 +/- 123, n = 6, p < 0.05). This increase in plasma LPL was significantly higher in the heparin/dihydroergotamine-group compared to the Fragmin-group (p < 0.05). In both groups, the enzyme activity gradually decreased during the next 2 days. The circulating level of non-esterified fatty acids increased post-operatively only in the heparin/dihydroergotamine-group. Thus, the lower lipolytic effect of Fragmin compared to standard heparin is detectable using thromboprophylactic doses during surgery in patients on a standard hospital diet. From a theoretical viewpoint, the use of Fragmin is advantageous in patients with myocardial ischaemia and patients risking respiratory distress problems due to a low circulating level of non-esterified fatty acids.