Thrombolytic drugs in acute myocardial infarction

Intrapleural therapy in management of complicated parapneumonic effusions and empyema

Empyema thoracis causes high mortality, and its incidence is increasing in both children and adults. Parapneumonic effusions (PPEs) develop in about one-half of patients hospitalized with pneumonia, and their presence increases mortality by about four-fold. PPEs can be divided into simple PPEs, complicated PPEs, and frank empyema. Two guideline statements on the management of PPEs in adults have been published by the British Thoracic Society (BTS) and the American College of Chest Physicians; a third guideline statement published by the BTS focused on management of PPEs in children. The two adult guideline statements recommend drainage of the pleural space in complicated PPEs and frank empyema. They also recommend the use of intrapleural fibrinolysis in those who do not show improvement. The pediatric guideline statement recommends adding intrapleural fibrinolysis to those treated by tube thoracostomy if they have loculated pleural space or thick pus. Published guideline statements on the management of complicated PPEs and empyema in adults and children recommend the use of intrapleural fibrinolysis in those who do not show improvement after pleural space drainage. However, published clinical trial reports on the use of intrapleural fibrinolysis for the treatment of pleural space sepsis suffer from major design and methodologic limitations. Nevertheless, published reports have shown that the use of intrapleural fibrinolysis does not reduce mortality in adults with parapneumonic effusions and empyema. However, intrapleural fibrinolysis enhances drainage of infected pleural fluid and may be used in patients with large collections of infected pleural fluid causing breathlessness or respiratory failure, but a proportion of these patients will ultimately need surgery for definite cure. Intrapleural streptokinase and urokinase seem to be equally efficacious in enhancing infected pleural fluid drainage in adults. In most of the published studies in adults, the use of intrapleural fibrinolysis was not associated with serious side effects. There is emerging evidence that the combination of intrapleural tissue plasminogen activator (tPA) and deoxyribonuclease (DNase) is significantly superior to tPA or DNase alone or placebo in improving pleural fluid drainage in patients with pleural space infection. In children, intrapleural fibrinolysis has not been shown to reduce mortality, but has been shown to enhance drainage of the pleural space and was safe. In addition, two prospective, randomized trials have shown that intrapleural fibrinolysis is as effective as video-assisted thoracoscopic surgery for the treatment of childhood empyema and is a more cost-effective treatment and therefore should be the primary treatment of choice.

Emerging anticoagulant and thrombolytic drugs

Since its discovery, heparin has been used intensely as an anticoagulant for several medical and surgical indications. However, efforts are in progress to replace heparin because of its serious complications, such as intraoperative and postoperative bleeding, osteoporosis, alopecia, heparin resistance, heparin rebound, heparin-induced thrombocytopenia (HIT) and thrombosis syndrome (HITTS), and other disadvantages. Significant developments in the field of new anticoagulants have resulted in the evaluation and introduction of low molecular weight heparins (LMWHs) and heparinoids, hirudin, ancrod, synthetic peptides and peptidomimetics. However, despite significant progress in the development of these new anticoagulants, a better or an ideal anticoagulant for cardiovascular patients is not yet available and heparin still continues to amaze both basic scientists and the clinicians. To minimise the adverse effects of heparin, newer approaches to optimise its use in combination with the new anticoagulants may provide better clinical outcome. In our experience, the off-label use of argatroban at a dose of 300 microg/kg iv. bolus followed by 10 microg/kg/minute infusion in combination with aggrastat (a glycoprotein [GP] IIb/IIIa inhibitor) at a dose of 10 microg/kg iv. bolus followed by an infusion of 0.15 microg/kg/minute in patients with HIT undergoing percutaneous coronary interventions resulted in elevation of celite activated clotting time (ACT) to 300 seconds followed by a gradual decline and the ACT remained above 200 seconds even after 200 min of drug administration. A bewildering array of newer anticoagulants now exist, such as LMWHs and heparinoids, indirect or direct thrombin inhibitors, oral thrombin inhibitors, such as melagatran (AstraZeneca) and HC-977 (Mitsubishi Pharmaceuticals), Factor IXa inhibitors, indirect or direct Factor Xa inhibitors, Factor VIIa/tissue factor (TF) pathway inhibitor, newer antiplatelet agents, such as GPIIb/IIIa inhibitors, fibrin specific thrombolytic agent, such as tenecteplase and modulation of the endogenous fibrinolytic activity by thrombin activatable fibrinolytic inhibitor (TAFI), Factor XIIIa inhibitors and PAI-1 inhibitors. The quest for newer anticoagulant, antiplatelet and fibrinolytic agents will continue until ideal agents are found.