Stabilization of a freeze-dried recombinant streptokinase formulation without serum albumin

Formulation Development for Hydrophobic Therapeutic Proteins

The major challenges in formulation development for hydrophobic proteins are low solubility often combined with a strong tendency for adsorption. Human serum albumin (HSA) is frequently used as excipient to overcome these problems. Due to several drawbacks with HSA, new ways need to be found to circumvent the use of this excipient in protein formulations. One possible approach is to select an appropriate formulation pH and ionic strength in combination with excipients that provide sufficient stability and solubility for the hydrophobic protein. A reduction in adsorption can be achieved by adding surfactants or using special containers.

Synthesis, characterization, and in vitro activity of dendrimer-streptokinase conjugates

Dendrimer conjugation with low molecular weight drugs has been of increasing interest recently for improving pharmacokinetics, targeting drugs to specific sites, and facilitating cellular uptake. Opportunities for increasing the performance of relatively large therapeutic proteins such as streptokinase (SK) using dendrimers are being explored in this study. Using the active ester method, a series of streptokinase-poly(amido amine) (PAMAM) G3.5 conjugates were synthesized with varying amounts of dendrimer-to-protein molar ratios. Characterization of these conjugates by GPC, IEC, and native-PAGE suggested that the conjugation reaction was successful, resulting in relatively pure SK-dendrimer conjugates. The conjugate made with an equimolar ratio of dendrimer to streptokinase (1:1) exhibited the highest enzymatic activity retention ( approximately 80% retained) that has been reported so far for conjugated streptokinase with macromolecules such as PEG or dextran. SK conjugates with higher streptokinase-to-dendrimer molar ratios (1:10 and 1:20) exhibited lower initial enzymatic activities. However, these conjugates showed sustained thrombolytic activity in plasma, perhaps due to the release of SK from the conjugate. All of the SK conjugates displayed significantly improved stability in phosphate buffer solution, compared to free SK. The high coupling reaction efficiencies and the resulting high enzymatic activity retention achieved in this study could enable a desirable way for modifying many bioactive macromolecules with dendrimers.

Pharmacovigilance program to monitor adverse reactions of recombinant streptokinase in acute myocardial infarction

Background

Streptokinase (SK) is an effective fibrinolytic agent for the treatment of acute myocardial infarction (AMI). The objective of the present study was to assess the adverse drug reactions (ADRs) associated with intravenous recombinant SK in patients with AMI in routine clinical practice.

Methods

A national, prospective and spontaneous reporting-based pharmacovigilance program was conducted in Cuba. Patient demographics, suspected ADR description, elements to define causality, and outcomes were documented and analyzed.

Results

A total of 1496 suspected ADRs identified in 792 patients out of the 1660 (47.7 %) prescriptions reported in the program, were received from July 1995 to July 2002. Most of the patients (71.3%) were male, 67.2% were white and mean age was 61.6 ± 13.0 years. The mean time interval between the onset of symptoms and the start of the SK infusion was 4.9 ± 3.7 h. The most frequently reported ADRs were hypotension, arrhythmias, chills, tremors, vomiting, nauseas, allergy, bleeding and fever. ADR severity was 38% mild, 38% moderate, 10% severe, and 4% very severe. Only 3 patients with hemorrhagic stroke were reported. Seventy-two patients died in-hospital mainly because of cardiac causes associated with the patient's underlying clinical condition. Mortality was 3 times more likely in patients suffering arrhythmias than in those without this event (odds ratio 3.1, 95% CI: 1.8 to 5.1). Most of the reported ADRs were classified as possibly or probably associated with the study medication.

Conclusion

Recombinant SK was associated with a similar post-marketing safety profile to those suggested in previous clinical trials.