March 1, 2007 (Vol. 27, No. 5)
Angelo DePalma Ph.D. Writer GEN
The Foundation of Dosage and Administration Requires Input From a Cadre of Scientists
Coming up with the right formulation of a drug—the final format, including ingredients—has always involved art as well as science. For formulation determines a biotechnology candidate’s stability, shelf-life, distribution, dosing, bioavailability, market acceptance, and, in some cases, safety and efficacy.
As more biotech products reach the marketplace, lyophilization is becoming an essential formulation strategy for many companies. Advantages of lyophilized versus solution-based products include ease of storage and shipping. Many lyophilized products are stable at room temperature.
Every formulation project at Avid Biosciences (www.avidbio.com) begins with preformulation work, according to Harish Kumar, Ph.D., senior director for product formulations. “Biotech companies need to recognize that formulation takes time and they need to commit resources to it right from the beginning. It can take one or two years to develop a workable formulation.”
Kumar’s team characterizes the protein for structure, pH stability, viscosity, tendency toward aggregation, glycosylation status, and the impact of salts, ionic strength, oxidation, osmolality, and protein stability. Only after determining a pH within physiologic range (6 to about 8) that confers optimal stability does Avid begin investigating lyophilization parameters that apply during freezing and primary and secondary drying.
Investigators determine the thermal properties of freezing, particularly eutectic point and melting temperature, through electrical measurements. When necessary, Avid employs excipients—lyoprotectants to maintain protein stability through the freeze-dry cycles and bulking agents, such as sucrose, trehalose, and disaccharides, to maintain the physical integrity of the lyophilization cake.
Generally, the more complex a product the earlier developers should think about its final formulation. “Many of our customers don’t think about formulation until late in development,” says Dr. Kumar, “when stability becomes an issue.”
Wyeth Biopharma (www.wyeth.com) has had its share of ground-breaking products, with its Enbrel® tumor necrosis factor blocker for autoimmune diseases, Refacto® antihemophilic factor, and Benefix® coagulation factor IX in addition to 22 proteins in its pipeline. Ease of administration is especially relevant for hemophilia drugs, which are injected by the patients themselves.
According to executive vp Cavan Redmond, Wyeth’s success strategy includes early innovations that generate greater value to patients and caregivers. These include making them safer, more easily dosed, or more convenient to administer (or self-administer).
To achieve these objectives, Wyeth focuses significant resources on formulation. “Formulation is a foundation of dosage and administration,” says Redmond. It requires the input of protein chemists, engineers, pharmacists, and biochemists toward understanding how formulation relates to safety and efficacy.
Wyeth’s aim, to commercialize molecules quickly, entails developing an effective, commercializable formulation early in the product’s lifecycle. By the time a Wyeth molecule has entered clinical trials, the formulation is set except, perhaps, for minor differences between the clinical- and commercial-stage dosage forms.
Wyeth considers input from patients, caregivers, and family as essential to developing a dosage form and formulation that serves its markets. For example, at one time patients infused Wyeth’s Refacto hemophilia drug anywhere from weekly to every few days, depending on their weight. Some patients needed to open multiple vials of the lyophilized product and mix them before infusion. This presented special dosing problems to rapidly growing children and adolescents whose dosing requirements thus kept changing. In response, Wyeth developed age-matched dosage forms that significantly reduced the number of steps required for the infusion. As a result, patients become more self-sufficient in Refacto administration at an earlier age than with the original formulation.
Formulation can create new markets for products as well. Medtronic’s (www.medtronic.com) InFUSE spine regeneration combination product uses bone morphogenic protein, manufactured by Wyeth, within an absorbable collagen sponge implanted in the vicinity of damaged spinal disks. The companies are now working on a related product that will not require surgery for implantation.
Aside from PEGylation and other sustained-release formats, formulation as a strategy for lifecycle extension is more limited with biologics than for small molecules. However, there is still great interest in applying these techniques to protein drugs. In February, Wyeth entered a collaboration with Nautilus Biotech (www.nautilusbiotech.com) to apply Nautilus technology to extend the circulating half-life of Wyeth’s Factor IX product.
Make or Break
Formulation can signal the success or failure of certain products, especially those with dosing, storage, shipping, or administration issues, such as vaccines. In 2004, Vaxgen (www.vaxygen.com) was awarded an $875-million contract to supply 75 million doses of anthrax vaccine to the U.S. government. Then, in late 2006, the FDA halted clinical testing of the product after determining its formulation rendered it unstable for long-term storage. The HHS subsequently cancelled its contract with Vaxgen. In the aftermath, the company laid off about half its employees and its CEO was forced to resign.
MedImmune (www.medimmune.com) ships its successful FluMist® live attenuated influenza vaccine frozen The company expects to receive approval for a liquid formulation that is stable at refrigerator temperatures. Such a vaccine differs from the frozen product in its use of ingredients, plus an additional ultracentrifugation purification step.
The difference between refrigerator and freezer temperatures, 30–40ºC, translates to easier handling and may improve acceptance of FluMist’s delivery system. FluMist is delivered through a small glass syringe that sprays the vaccine into the upper airways inducing systemic immunity as well as protection within tissues most likely to encounter influenza virus.
For now FluMist is produced in eggs, as are all U.S.-licensed flu vaccines. MedImmune, however, recently received a contract from the HHS to accelerate its efforts at developing an influenza product from mammalian cells, which will introduce additional formulation challenges.
SRI (www.sri.com) has been awarded a grant to develop an anthrax vaccine that is easier to administer than the current product, which requires sixteen injections. SRI’s formulation will be an intranasal application that sticks to the nasal mucosa for an extended time, where the antigen will be extracted over several days by cells likely to be exposed, in a real-life situation, to anthrax. According to senior director of pharmaceutical sciences Helen Parish, individuals will be able to self-administer the nasal formulation.
The Re-emergence of Peptides
Formulation is also key to drugs or entire drug classes. The re-emergence of peptide drugs, after a 15-year lull due to delivery difficulties, illustrates how much bio-drugs rely on formulation strategies.
Much has been written on the importance of parenteral products and the rise of biotech. As critical as the injectible/infusion route may be, companies are always looking to improve delivery routes and perhaps reduce the need for injection. Pfizer’s(www.pfizer.com) Exubera® inhalable insulin powder is an obvious success story.
One of the biggest boosters of peptide drugs using novel formulations has been Unigene (www.unigene.com) CEO, Warren Levy, Ph.D. “Formulation is the key to peptide delivery,” says Dr. Levy. He notes that companies are investigating nasal, oral, inhalable, and even transdermal peptide delivery. Although the chemical composition of peptides presents challenges to formulation-delivery strategies, Dr. Levy believes that, as with small molecule drugs, the oral route is highly preferable.
Unigene has demonstrated that oral delivery is possible with peptides through enterically coated tablets or capsules that protect ingredients from proteolytic enzymes in the gut. The key ingredients are an organic acid that temporarily inactivates digestive enzymes and a detergent that transiently opens up tight junctions in the digestive tract, allowing small peptides to enter the system through the stomach.
The company has had a hand, through application of its high-yield peptide expression and nasal delivery technologies, in the success of Fortical® nasal calcitonin spray. Unigene has also licensed technology to GlaxoSmithKline (www.gsk.com) for an oral formulation of parathyroid hormone and is working through a supply agreement with Novartis (www.novartis.com) on that firm’s development-stage calcitonin product.
Novozymes Delta Ltd (www.biopharmaceuticals.novozymes.com) develops and manufactures recombinant protein products using Saccharomyces cerevisiae and licenses its yeast-based expression system to pharmaceutical, healthcare, and biotech partners. The company, which was formerly known as Delta Biotechnology, offers products that include yeast-derived recombinant human albumin (Recombumin(R), a protein stabilizer, and recombinant human transferrin (DeltaFerrin(tm), which assists in critical iron uptake in protein-producing cells. Merck & Co. (www.merck.com) uses the recombinant albumin product Recombumin(R) in formulating its M-M-R(R)-II (measles, mumps, rubella) human vaccine to replace serum-derived albumin. Novozymes Delta plans to launch its transferrin product in May.
Advantages of recombinant, versus human-derived albumin, are numerous; improved quality and consistency are the most significant from a manufacturing perspective. Since the product cannot pass on animal diseases, products formulated with it are safer and less likely to experience recall.
Regulatory bodies were particularly cautious about Recombumin since it is a recombinant protein and makes up a significant fraction of the delivered drug. Novozymes Delta Ltdtherefore conducted a large Phase I evaluation of the protein’s safety and tolerability. Novozymes Delta Ltd’s regulatory submissions included a drug master file and a safety/tolerability package.
No clinical data needs to be submitted for the transferrin product because it is not delivered to patients.