cardiovascular-agents and Thrombocytopenia

To review the features of randomized clinical trials (RCTs) used in the development of agents that may protect against chemotherapy-induced toxicities, including trials of the cardioprotective agent dexrazoxane, hematologic growth factors, and amifostine; to suggest recommendations based on information gained from such trials and improvements in the design of ongoing and future trials.. Critical review of reports of RCTs obtained from a Medline search, references from these articles, and review of trials listed in the physician data query (PDQ) clinical trials data base.. Several of the phase III trials did not use a format of comparing widely accepted strategies of chemotherapy with and without a protective agent. Instead, patients in the control arms of some of the trials have been exposed to more prolonged use or increased dosage of toxic chemotherapy that placed them at greater risk of the toxicity the protective agent was designed to prevent (eg, cardiotoxicity in trials of dexrazoxane, myelosuppression or thrombocytopenia in trials of growth factors).. RCTs have shown clear evidence of biologic activity for the protective agents, but this does not imply therapeutic benefit as compared with alternative strategies such as avoidance of prolonged use of cardiotoxic agents or use of standard doses of chemotherapy. Ongoing and future trials of protective agents should be modified to avoid undue risk to patients.

Topics: Amifostine; Antineoplastic Agents; Cardiovascular Agents; Clinical Trials, Phase III as Topic; Heart Diseases; Hematopoietic Cell Growth Factors; Humans; Leukopoiesis; Randomized Controlled Trials as Topic; Razoxane; Research Design; Thrombocytopenia

Thrombocytopenia and thromboembolism(s) may develop in heparin immune-mediated thrombocytopenia (HIT) patients after reexposure to heparin. At the Onassis Cardiac Surgery Center, 530 out of 17,000 patients requiring heart surgery over an 11-year period underwent preoperative HIT assessment by ELISA and a three-point heparin-induced platelet aggregation assay (HIPAG). The screening identified 110 patients with HIT-reactive antibodies, out of which 46 were also thrombocytopenic (true HIT). Cardiac surgery was performed in HIT-positive patients under heparin anticoagulation and iloprost infusion. A control group of 118 HIT-negative patients received heparin but no iloprost during surgery. For the first 20 patients, the dose of iloprost diminishing the HIPAG test to ≤5% was determined prior to surgery by in vitro titration using the patients' own plasma and donor platelets. In parallel, the iloprost "target dose" was also established for each patient intraoperatively, but before heparin administration. Iloprost was infused initially at 3 ng/kg/mL and further adjusted intraoperatively, until ex vivo aggregation reached ≤5%. As a close correlation was observed between the "target dose" identified before surgery and that established intraoperatively, the remaining 90 patients were administered iloprost starting at the presurgery identified "target dose." This process significantly reduced the number of intraoperative HIPAG reassessments needed to determine the iloprost target dose, and reduced surgical time, while maintaining similar primary clinical outcomes to controls. Therefore, infusion of iloprost throughout surgery, under continuous titration, allows cardiac surgery to be undertaken safely using heparin, while avoiding life-threatening iloprost-induced hypotension in patients diagnosed with HIT-reactive antibodies or true HIT.

Topics: Adult; Aged; Aged, 80 and over; Antibodies; Anticoagulants; Aortic Aneurysm; Blood Platelets; Cardiac Valve Annuloplasty; Cardiovascular Agents; Coronary Artery Bypass; Drug Administration Schedule; Drug Monitoring; Female; Heparin; Humans; Iloprost; Male; Middle Aged; Perioperative Care; Platelet Aggregation; Platelet Count; Thrombocytopenia; Thromboembolism; Treatment Outcome

The anthracyclines daunorubicin and doxorubicin and the epipodophyllotoxin etoposide are potent DNA cleavage-enhancing drugs that are widely used in clinical oncology; however, myelosuppression and cardiac toxicity limit their use. Dexrazoxane (ICRF-187) is recommended for protection against anthracycline-induced cardiotoxicity.. Because of their widespread use, the hematologic toxicity following coadministration of dexrazoxane and these three structurally different DNA cleavage enhancers was investigated: Sensitivity of human and murine blood progenitor cells to etoposide, daunorubicin, and doxorubicin +/- dexrazoxane was determined in granulocyte-macrophage colony forming assays. Likewise, in vivo, B6D2F1 mice were treated with etoposide, daunorubicin, and doxorubicin, with or without dexrazoxane over a wide range of doses: posttreatment, a full hematologic evaluation was done.. Nontoxic doses of dexrazoxane reduced myelosuppression and weight loss from daunorubicin and etoposide in mice and antagonized their antiproliferative effects in the colony assay; however, dexrazoxane neither reduced myelosuppression, weight loss, nor the in vitro cytotoxicity from doxorubicin.. Although our findings support the observation that dexrazoxane reduces neither hematologic activity nor antitumor activity from doxorubicin clinically, the potent antagonism of daunorubicin activity raises concern; a possible interference with anticancer efficacy certainly would call for renewed attention. Our data also suggest that significant etoposide dose escalation is perhaps possible by the use of dexrazoxane. Clinical trials in patients with brain metastases combining dexrazoxane and high doses of etoposide is ongoing with the aim of improving efficacy without aggravating hematologic toxicity. If successful, this represents an exciting mechanism for pharmacologic regulation of side effects from cytotoxic chemotherapy.

Topics: Anemia; Animals; Antibiotics, Antineoplastic; Antineoplastic Agents; Cardiovascular Agents; Cell Culture Techniques; Colony-Forming Units Assay; Daunorubicin; Doxorubicin; Etoposide; Female; Leukopenia; Mice; Neutropenia; Razoxane; Thrombocytopenia

The stable PGI2-analogue iloprost and the TXA2-receptor antagonist sulotroban were investigated for possible cooperative effects on platelet function and experimental thrombus formation in guinea pigs and rats. Iloprost and sulotroban inhibit intravascular platelet aggregation in guinea pigs and rats induced by the stable endoperoxide U 46.619 and collagen, with iloprost being the more potent and (for collagen) more efficacious drug. Combinations of both compounds show synergistic or additive effects on in vivo platelet function. Thrombus formation in rats induced by vascular damage is strongly reduced by combining doses of iloprost and sulotroban (BM 13.177) which given alone are ineffective. These results suggest a cooperative enhancement of antiplatelet and antithrombotic effects for combinations of iloprost and sulotroban. In view of disadvantages of currently used platelet inhibitors this cooperativity may offer a new approach in antiplatelet therapy.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Cardiovascular Agents; Collagen; Drug Synergism; Epoprostenol; Fibrinolytic Agents; Guinea Pigs; Iloprost; Platelet Aggregation Inhibitors; Prostaglandin Endoperoxides, Synthetic; Rats; Sulfonamides; Thrombocytopenia; Thrombophlebitis; Thromboxanes

Recurrent thrombocytopenia, thrombosis, or sudden death may develop in patients with heparin-induced thrombocytopenia who are reexposed to heparin. Three patients came to us in whom a diagnosis of heparin-induced thrombocytopenia had been made on the basis of clinical and serologic evidence; these patients required reexposure to heparin because of urgent cardiac surgery. Therefore, we evaluated the ability of iloprost (ZK36374), a new analogue of prostacyclin, to prevent heparin-dependent activation of platelets and thereby permit obligatory heparinization for safe extracorporeal circulation. Before operation, we demonstrated that iloprost prevented both heparin-dependent platelet aggregation and tritiated (3H)-serotonin release in vitro. Therefore a continuous infusion of iloprost was begun 1 hour before heparinization and was continued throughout cardiopulmonary bypass and for an additional 15 minutes after protamine administration. The mean platelet count of 130,000/microliters before operation remained stable, and no spontaneous platelet aggregation was observed in samples of platelet-rich plasma obtained before cardiopulmonary bypass but after heparin administration. Similarly, after heparin administration but before bypass, platelet responsiveness to adenosine diphosphate remained unchanged when compared with preoperative values. Plasma levels of platelet factor 4 increased from 26 +/- 1 ng/ml (mean +/- standard error) to 843 +/- 383 ng/ml after heparin administration but actually decreased throughout cardiopulmonary bypass to 52 +/- 25 ng/ml. Beta-thromboglobulin levels increased from 103 +/- 16 to 244 +/- 94 ng/ml with heparinization. The mean bleeding time was 10.5 minutes preoperatively and 13.3 minutes postoperatively. The mean amount of postoperative chest tube drainage (duration: 12 hours) was 432 +/- 67 ml. Thus, despite the confirmed presence of heparin-dependent platelet-activating factor in the plasma of these three patients, iloprost prevented heparin-induced platelet activation during cardiopulmonary bypass while preserving platelet function, as would be desired for postoperative hemostasis.

Topics: Adult; Cardiopulmonary Bypass; Cardiovascular Agents; Epoprostenol; Fibrinopeptide A; Heparin; Humans; Iloprost; Middle Aged; Platelet Aggregation; Platelet Count; Platelet Factor 4; Thrombocytopenia; Thromboxane B2

Topics: Cardiovascular Agents; Digitalis; Humans; Purpura; Purpura, Thrombocytopenic; Thrombocytopenia