The 'precautionary principle' as a guide for future drug development

Partial characterization and anticoagulant activity of sulfated galactan from the green seaweed Halimeda opuntia

The number of deaths associated with cardiovascular diseases (CVD) increases every year, leading to an intense search for new compounds that may be employed as anticoagulants. One of the classes of bioprospected molecules comprises sulfated polysaccharides (SP) from seaweed, as heparin displays many adverse effects associated with its use. The present study aimed to characterize and evaluate the anticoagulant potential of SP extracted from the green algae Halimeda opuntia. Four PS-rich fractions, F23, F44, F60 and F75, were obtained by proteolytic digestion in papain followed by ethanol precipitation. The presence of SP was confirmed by agarose gel electrophoresis, revealing different populations in each fraction. The F44 fraction is noteworthy compared to the other fractions, presenting a 5% yield compared to the initial algae weight and anticoagulant activity revealed by the activated partial thromboplastin time (APTT) assay (intrinsic/common coagulation pathway). Surprisingly, F44 purification (SP peak P1F44) resulted in prothrombin time (PT) activity (extrinsic coagulation pathway) at a 160 µg/mL, in addition to enhanced APTT activity. The P1F44 anticoagulant activity mechanism was shown to be dependent on two coagulations factors, IIa and Xa, more potent via IIa. Future assessments will be performed to assess this fraction in the medical clinic.

Problems with precaution: the transfusion medicine experience

The precautionary principle is a dominant paradigm governing risk-based decision-making. Today, there are increasing pressures to re-examine aggressive precautionary approaches, and to assess how the principle should be applied in the modern system. In this paper, we examined three key applications of precautionary approaches in the field of transfusion medicine to provide insight into the risks and benefits of these approaches. The three case studies examined were the donor deferral policies to safeguard against transfusion transmission of human immunodeficiency virus, variant Creutzfeldt-Jacob disease, and, lastly, xenotropic murine leukemia virus-related virus. Characterization of precautionary applications was conducted using an embedded case study design. Our findings indicate that transfusion transmission mitigation strategies have become increasingly aggressive in the face of theoretical risks. In contrast, the review processes for implementation and reversal of precautionary policies have been slow, and historical donor deferral policies are still in place today. Application of precautionary approaches has proved challenging with both benefits and pitfalls. In light of emerging threats to the blood system, policy-makers should consider the implementation of frameworks to guide the appropriate application of precaution in transfusion medicine in the future.

Parental preferences regarding administration of an animal-derived versus a synthetic medication to newborn infants

AIM

We examined the perceptions of parents with regard to animal-derived versus synthetic medications of comparable efficacy. We hypothesized that this issue is a concern in neonatal care and that the perceptions of parents from one geographical location would be similar to those of another.

METHODS

A survey was distributed to parents of neonates admitted to a neonatal intensive care unit of a southeastern hospital.

RESULTS

Of 153 parents surveyed, 150 (98%) responded. More mothers than fathers completed the surveys (113 vs. 34). Fifty-six percent of participants indicated a college or higher education; 40% had an income of $51,000/yr or higher. Thirty-four percent of parents had concerns about animal-derived medications, 41% preferred a synthetic medication of equivalent efficacy, and 69% would like to be informed if a medication was animal-derived.

CONCLUSION

Parents have concerns about exposing neonates to animal-derived medication and wish to be informed if an animal-derived medication is being considered.

Prudent precaution in clinical trials of nanomedicines

Clinical trials of nanotechnology medical products present complex risk management challenges that involve many uncertainties and important risk-risk trade-offs. This paper inquires whether the precautionary principle can help to inform risk management approaches to nanomedicine clinical trials. It concludes that prudent precaution may be appropriate for ensuring the safety of such trials, but that the precautionary principle itself, especially in its more extreme forms, does not provide useful guidance for specific safety measures.

New parenteral anticoagulants in development

The therapeutic armamentarium of parenteral anticoagulants available to clinicians is mainly composed by unfractionated heparin (UFH), low-molecular-weight heparin (LMWH), fondaparinux, recombinant hirudins (i.e. bivalirudin, desirudin, lepirudin) and argatroban. These drugs are effective and safe for prevention and/or treatment of thromboembolic diseases but they have some drawbacks. Among other inconveniences, UFH requires regular anticoagulant monitoring as a result of variability in the anticoagulant response and there is a risk of serious heparin-induced thrombocytopaenia (HIT). LMWH, fondaparinux and recombinant hirudins are mainly cleared through the kidneys and their use in patients with severe renal insufficiency may be problematic. LMWH is only partially neutralized by protamine while fondaparinux and recombinant hirudins have no specific antidote. Novel anticoagulants in development for parenteral administration include new indirect activated factor Xa (FXa) inhibitors (idrabiotaparinux, ultra-low-molecular-weight heparins [semuloparin, RO-14], new LMWH [M118]), direct FXa inhibitors (otamixaban), direct FIIa inhibitors (flovagatran sodium, pegmusirudin, NU172, HD1-22), direct FXIa inhibitors (BMS-262084, antisense oligonucleotides targeting FXIa, clavatadine), direct FIXa inhibitors (RB-006), FVIIIa inhibitors (TB-402), FVIIa/tissue factor inhibitors (tifacogin, NAPc2, PCI-27483, BMS-593214), FVa inhibitors (drotrecogin alpha activated, ART-123) and dual thrombin/FXa inhibitors (EP217609, tanogitran). These new compounds have the potential to complement established parenteral anticoagulants. In the present review, we discuss the pharmacology of new parenteral anticoagulants, the results of clinical studies, the newly planned or ongoing clinical trials with these compounds, and their potential advantages and drawbacks over existing therapies.

Pharmacological profiles of animal- and nonanimal-derived sulfated polysaccharides--comparison of unfractionated heparin, the semisynthetic glucan sulfate PS3, and the sulfated polysaccharide fraction isolated from Delesseria sanguinea

Sulfated polysaccharides (SP) such as heparin are known to exhibit a wide range of biological activities, e.g., anticoagulant, anti-inflammatory, and antimetastastic effects. However, since the anticoagulant activity of heparin is dominating, its therapeutic use for other medical indications is limited due to an associated risk of bleeding. Further disadvantages of heparin are its animal origin, the shortage of resources, and its complex and variable composition. However, SP without these limitations may represent a substance class with good prospects for applications other than anticoagulation. In this study, the in vitro pharmacological profiles of two nonanimal-derived SP were investigated in comparison with unfractionated heparin. One is the natural SP fraction from the red algae Delesseria sanguinea (D.s.-SP). The other one is the chemically defined PS3, a semisynthetic β-1,3-glucan sulfate with proven in vivo anti-inflammatory and antimetastatic activities. All three polysaccharides were examined in vitro for their inhibitory effects on the coagulation and complement system, polymorphonuclear neutrophil elastase, hyaluronidase, matrix metalloproteinase-1, heparanase, and p-selectin-mediated cell adhesion. Compared with heparin, the nonanimal-derived polysaccharides have a four times weaker anticoagulant activity, but mostly exhibit stronger (1.4–224 times) effects on test systems investigating targets of inflammation or metastasis. According to their different structures, PS3 and D.s.-SP differ in their pharmacological profile with PS3 being the strongest inhibitor of heparanase and cell adhesion and D.s.-SP being the strongest inhibitor of hyaluronidase and complement activation. Considering both pharmacological profile and pharmaceutical quality parameters, PS3 represents a candidate for further development as an anti-inflammatory or antimetastatic drug whereas D.s.-SP might have perspectives for cosmetic applications.

Should the precautionary principle guide our actions or our beliefs?

Two interpretations of the precautionary principle are considered. According to the normative (action-guiding) interpretation, the precautionary principle should be characterised in terms of what it urges doctors and other decision makers to do. According to the epistemic (belief-guiding) interpretation, the precautionary principle should be characterised in terms of what it urges us to believe. This paper recommends against the use of the precautionary principle as a decision rule in medical decision making, based on an impossibility theorem presented in Peterson (2005). However, the main point of the paper is an argument to the effect that decision theoretical problems associated with the precautionary principle can be overcome by paying greater attention to its epistemic dimension. Three epistemic principles inherent in a precautionary approach to medical risk analysis are characterised and defended.

Drug safety and the media

This article reviews the problems that may arise as a result of media coverage of drug safety issues. In order to promote more balanced coverage and avoid unnecessary scares, professionals working in the area of drug safety should rethink their strategies for dealing with the media.