Nanomaterials Raise New Challenges - Pharmaceutical Technology

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Nanomaterials Raise New Challenges
Scientists are pursuing nanotechnology-based drug delivery and production technologies, despite protests about unsafe products.

Pharmaceutical Technology

Manufacturing challenges

Efforts to ensure the safety of nanomaterials also require manufacturers to assess fully how nano-sizing drugs affects their dissolution rate, solubility, and onset of therapeutic action. Although these features may permit lower dosages and simplify administration, they also can raise concerns about safety and product quality.

A prime challenge for manufacturers is to ensure reproducibility and quality of nanotechnology products. Critical quality attributes include:

  • particle size and size distribution;
  • surface area, surface chemistry, porosity;
  • hydrophilicity, surface-change density;
  • purity and sterility;
  • stability (aggregation, protein interactions).

Issues to consider during nanotechnology product characterization
Characterization of nanotechnology products may raise unique considerations (see sidebar, "Issues to consider during nanotechnology product characterization"). Manufacturers must identify available tools for assessing the critical physical and chemical properties of the products, including residual solvents, processing variables, impurities, and excipients. Validated assays are important for detecting and quantifying nanoparticles in tissues and medical products and for determining how physical characteristics may affect product quality and performance.

All of these issues are important in demonstrating full control of a production process and justifying drug-release parameters and bioequivalence-testing approaches, Sadrieh points out. The process of developing test methods and specifications that clearly can control product and process to scale up to mass production may be complicated by a lack of reference materials and standards. Additional standard test methods may be needed to develop nanoparticles for drugs and biologics.

To assist manufacturers in developing appropriate safety and quality-control methods and to ensure appropriate regulatory strategies, FDA is conducting laboratory research to understand better the ability of preclinical screening tests to identify potential risks and toxicities. CDER scientists are examining the effect of particle size on sunscreens that contain zinc oxide and titanium dioxide nanoparticles, as well as issues related to the manufacture of nanoformulations and the characterization of physical and chemical properties. Tests are being conducted to determine whether excipients or different process and formulation variables may affect nanotechnology product characteristics, overall stability, and bioavailability. The Center for Biologics Evaluation and Research is developing a nanoparticle-based assay for detecting blood-borne viruses and for testing blood-cell compatibility of nanomaterials. Additional FDA research is evaluating skin penetration (in humans and animals) of nanoparticles in sunscreens.

The future of nanotechnology

At FDA's Science Forum in April, a panel of scientists discussed various nanotechnology developments affecting drugs and medical products. The researchers addressed factors related to toxicity and preclinical characterization of nanomaterials as part of an overview of emerging applications of nanotechnology for biology, imaging, and medicine.

FDA expects that nanotechnology will yield more combination products with multiple components, including a delivery system, therapy, imaging agent, and targeting agent. Such complex products will create challenges for FDA's Office of Combination Products in determining the primary mode of action, which is the basis for assigning products to a lead Center for application review.

In addition to the cancer agent Abraxane, FDA has approved nanoscale liposomes and microemulsions as well as MRI imaging agents and targeting agents. One antibacterial wound dressing incorporates silver nanoparticles, and a nano-based dental restorative has been created. FDA anticipates more nano-based new drugs and imaging agents will be on the way soon. Its Office of Science and Health Coordination oversees nanotechnology activities throughout the agency, including its participation on government-wide nanotechnology committees. CDER also has established a Nanotechnology Working Group to develop position papers and identify regulatory concerns in this area.

These issues are slated to be discussed in October at an FDA public meeting about scientific and regulatory issues related to products containing nanotechnological materials. The meeting will fit FDA's Critical Path Initiative, which aims to identify scientific hurdles that may inhibit the use of nanotechnology in medical product development. FDA hopes attendees will report on new nanotech drugs, on what scientific issues FDA should address, and on other regulatory concerns.

Jill Wechsler is Pharmaceutical Technology's Washington editor, 7715 Rocton Ave., Chevy Chase, MD 20815, tel. 301.656.4634,


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