Pharmacokinetics and Pharmacodynamics of Tissue Plasminogen Activator Administered Through an External Ventricular Drain

Thrombolysis for aneurysmal subarachnoid haemorrhage

BACKGROUND

Aneurysmal subarachnoid haemorrhage continues to cause a significant burden of morbidity and mortality despite advances in care. Trials investigating local administration of thrombolytics have reported promising results.

OBJECTIVES

- To assess the effect of thrombolysis on improving functional outcome and case fatality following aneurysmal subarachnoid haemorrhage - To determine the effect of thrombolysis on the risk of cerebral artery vasospasm, delayed cerebral ischaemia, and hydrocephalus following subarachnoid haemorrhage - To determine the risk of complications of local thrombolysis in aneurysmal subarachnoid haemorrhage SEARCH METHODS: We searched the Cochrane Central Register of Controlled Trials (last searched 9 March 2023), MEDLINE Ovid (1946 to 9 March 2023), and Embase Ovid (1974 to 9 March 2023). We also searched ClinicalTrials.gov and the WHO International Clinical Trials Registry Platform (ICTRP). We performed forward and reverse citation tracking of included studies using Google Scholar.

SELECTION CRITERIA

We included randomised controlled trials comparing subarachnoid thrombolysis via any route of administration into any anatomical site continuous with the subarachnoid space versus placebo, sham thrombolysis, or standard treatment.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies for inclusion in the review. We extracted study data and used version 2 of the Cochrane risk-of-bias tool for randomised trials to assess the risk of bias in the studies. We resolved any disagreement through discussion with a third author. Our primary outcome was poor functional outcome. Secondary outcomes were case fatality, haemorrhagic complications, cerebral artery vasospasm, delayed cerebral ischaemia, cerebral infarction, and hydrocephalus. We performed meta-analyses for each outcome and performed sensitivity analysis excluding studies at high risk of bias. We presented results as risk ratios (RRs) with 95% confidence intervals (CIs). We performed further sensitivity analysis by including all intervention groups from studies reporting more than one intervention group. For each outcome, we used the GRADE criteria to determine the certainty of the evidence.

MAIN RESULTS

We included eight studies from six countries in this review. The studies had a total of 410 participants, of whom 205 received thrombolysis. We identified three ongoing trials. We assessed one trial as having a high risk of bias for all outcomes; we assessed the remainder as having a low risk of bias or some concerns. Thrombolysis likely results in a reduction in poor functional outcome when compared to placebo or standard care (29.4% versus 39.7%, RR 0.73, 95% CI 0.56 to 0.94; 8 studies, 408 participants; moderate-certainty evidence). Thrombolysis likely results in little to no difference in case fatality (12.8% versus 17.7%, RR 0.71, 95% CI 0.46 to 1.10; 8 studies, 408 participants; moderate-certainty evidence). Thrombolysis may result in little to no difference in haemorrhagic complications (10.3% versus 7.2%, RR 1.40, 95% CI 0.73 to 2.68; 6 studies, 341 participants; low-certainty evidence). Thrombolysis likely results in a reduction in cerebral artery vasospasm (32.9% versus 47.6%, RR 0.70, 95% CI 0.54 to 0.91; studies, participants; moderate-certainty evidence), and may result in a reduction in delayed cerebral ischaemia (23.8% versus 38.2%, RR 0.62, 95% CI 0.45 to 0.88; studies, participants; low-certainty evidence). Thrombolysis may result in little to no difference in cerebral infarction (28.6% versus 37.5%, RR 0.76, 95% CI 0.44 to 1.31; studies, participants; low-certainty evidence), and likely results in little to no difference in the risk of hydrocephalus (18.3% versus 24.1%, RR 0.77, 95% CI 0.54 to 1.10; studies, participants; moderate-certainty evidence).

AUTHORS' CONCLUSIONS

There is some evidence that thrombolysis can probably improve outcomes after aneurysmal subarachnoid haemorrhage, without increasing the risk of haemorrhagic complications. Thrombolysis likely reduces the risk of poor functional outcome and cerebral artery vasospasm, and may reduce the risk of delayed cerebral ischaemia, but it likely makes little to no difference to case fatality or hydrocephalus, and may make little to no difference to the risk of cerebral infarction. However, the current evidence is still uncertain. The uncertainty is primarily due to the small total number of participants and outcome events. Data from further studies are required to confirm the efficacy of thrombolysis for improving outcomes after aneurysmal subarachnoid haemorrhage.

Comparison of pharmacokinetic properties of alteplase and tenecteplase. The future of thrombolysis in acute ischemic stroke

INTRODUCTION

The drug most frequently used for thrombolysis in cases of acute ischemic stroke (AIS) is alteplase. However, there is moderate-to-high-quality evidence that tenecteplase has similar or higher efficacy and safety. With improved pharmacokinetic properties over alteplase, tenecteplase could be a significant advantage in treating AIS.

AREAS COVERED

After conducting an extensive search on Scopus and PubMed, this manuscript reviews and compares the pharmacokinetic properties of alteplase and tenecteplase. Additionally, it provides information on pharmacodynamics, clinical efficacy, safety, tolerability, and drug-drug interactions.

EXPERT OPINION

The pharmacokinetic profile of alteplase and tenecteplase is derived from studies in patients with acute myocardial infarction. Thanks to its pharmacokinetic properties, tenecteplase is the drug closest to being the ideal fibrinolytic for AIS. Its longer half-life enables a single-bolus administration, which is particularly useful in emergencies. Tenecteplase has proven to have a good efficacy and safety profile in randomized clinical trials. Although we are awaiting the results of the ongoing phase 3 randomized clinical trials, we believe that tenecteplase has the potential to revolutionize the treatment of AIS through thrombolysis.

Tissue plasminogen activator with prolonged dwell time effectively evacuates pleural effusions

OBJECTIVES

Fibrinolytic therapy can be effective for management of complex pleural effusions. Tissue plasminogen activator (tPA, 10 mg) and deoxyribonuclease (DNAse) every 12 h with a dwell time of one hour is a common strategy based on published data. We used a simpler protocol of tPA (4 mg) without DNAse but with a longer dwell time of 12 h, repeated daily. We reviewed our results.

METHODS

Charts were reviewed and demographics, clinical data and treatment information were abstracted. Outcomes were assessed based on radiographic findings and need for surgery.

RESULTS

Two hundred and fifteen effusions in 207 patients (8 bilateral) were identified. 85% were either infectious or malignant. Two hundred and forty nine chest tubes were used: 84% were 10 Fr or 12 Fr and 7% were PleurX®. Five hundred and thirty one doses of tPA were given. The median number of doses per effusion was 2 (range 1-10), and 84% of effusions were treated with three or fewer doses. There were no significant bleeding complications. Median time to chest tube removal was 6 days (range 1 to 98, IQR 4 to 10). Drainage was considered complete for 78% of effusions, while 6% required decortication.

CONCLUSIONS

Low dose tPA daily with a 12 h dwell time may be as effective as the standard regimen of tPA and DNAse twice daily with one hour dwell. For most patients only three doses were required, and small pigtail catheters were sufficient. This regimen uses less medication and is logistically much easier than the current standard.

Blood clot contraction differentially modulates internal and external fibrinolysis

Essentials Clot contraction influences the rate of fibrinolysis in vitro. Internal fibrinolysis is enhanced ∼2-fold in contracted vs. uncontracted blood clots. External fibrinolysis is ∼4-fold slower in contracted vs. uncontracted blood clots. Contraction can modulate lytic resistance and potentially the clinical outcome of thrombosis. SUMMARY: Background Fibrinolysis involves dissolution of polymeric fibrin networks that is required to restore blood flow through vessels obstructed by thrombi. The efficiency of lysis depends in part on the susceptibility of fibrin to enzymatic digestion, which is governed by the structure and spatial organization of fibrin fibers. How platelet-driven clot contraction affects the efficacy of fibrinolysis has received relatively little study. Objective Here, we examined the effects of clot contraction on the rate of internal fibrinolysis emanating from within the clot to simulate (patho)physiological conditions and external fibrinolysis initiated from the clot exterior to simulate therapeutic thrombolysis. Methods Clot contraction was prevented by inhibiting platelet myosin IIa activity, actin polymerization or platelet-fibrin(ogen) binding. Internal fibrinolysis was measured by optical tracking of clot size. External fibrinolysis was determined by the release of radioactive fibrin degradation products. Results and Conclusions Clot contraction enhanced the rate of internal fibrinolysis ∼2-fold. In contrast, external fibrinolysis was ~4-fold slower in contracted clots. This dichotomy in the susceptibility of contracted and uncontracted clots to internal vs. external lysis suggests that the rate of lysis is dependent upon the interplay between accessibility of fibrin fibers to fibrinolytic agents, including clot permeability, and the spatial proximity of the fibrin fibers that modulate the effects of the fibrinolytic enzymes. Understanding how compaction of blood clots influences clot lysis might have important implications for prevention and treatment of thrombotic disorders.

Radiodensity of intraventricular hemorrhage associated with aneurysmal subarachnoid hemorrhage may be a negative predictor of outcome

OBJECTIVE The presence, extent, and distribution of intraventricular hemorrhage (IVH) have been associated with negative outcomes in aneurysmal subarachnoid hemorrhage (SAH). Several qualitative scores (Fisher grade, LeRoux score, and Graeb score) have been established for evaluating SAH and IVH. However, no study has assessed the radiodensity within the ventricular system in aneurysmal SAH patients with IVH. Prior studies have suggested that hemorrhage with a higher radiodensity, as measured by CT Hounsfield units, can cause more irritation to brain parenchyma. Therefore, the authors set out to investigate the relationship between the overall radiodensity of the ventricular system in aneurysmal SAH patients with IVH and their clinical outcome scores. METHODS The authors reviewed the records of 101 patients who were admitted to their institution with aneurysmal SAH and IVH between January 2011 and July 2015. The following data were collected: age, sex, Glasgow Coma Scale (GCS) score, Hunt and Hess grade, extent of SAH (none, thin, or thick/localized), aneurysm location, and Glasgow Outcome Scale (GOS) score. To evaluate the ventricular radiodensity, the initial head CT scan was loaded into OsiriX MD. The ventricular system was manually selected as the region of interest (ROI) through all pertinent axial slices. After this, an averaged ventricular radiodensity was calculated from the ROI by the software. GOS scores were dichotomized as 1-3 and 4-5 subgroups for analysis. RESULTS On univariate analysis, younger age, higher GCS score, lower Hunt and Hess grade, and lower ventricular radiodensity significantly correlated with better GOS scores (all p < 0.05). Subsequent multivariate analysis yielded age (OR 0.936, 95% CI 0.895-0.979), GCS score (OR 3.422, 95% CI 1.9-6.164), and ventricular density (OR 0.937, 95% CI 0.878-0.999) as significant independent predictors (p < 0.05). A receiver operating characteristic curve yielded 12.7 HU (area under the curve 0.625, p = 0.032, sensitivity = 0.591, specificity = 0.596) as threshold between GOS scores of 1-3 and 4-5. CONCLUSIONS This study suggests that the ventricular radiodensity in aneurysmal SAH patients with IVH, along with GCS score and age, may serve as a predictor of clinical outcome.