Fragile proteins and other biomolecules need protection as stable drug products. The larger a molecule is, the more difficult it will be to make, ship/store, and administer to patients. Biotech drug formulators have many concerns to juggle in their work, beginning with the physicochemical characteristics of an active molecule and including the reliability, cost, and availability of analytical methods; the array of excipients and adjuvants on the market; evolving delivery methods and devices; patient preferences and behavior, as well as the biology of diseases being treated; and even the concerns of legal, sales, and marketing groups.

Formulation is more than science, as a result, but science is its foundation. For years, it has been considered by many as an arena where luck and intuition play a role as well. But the work has become more methodical and quantifiable with new analytical technologies and the advent of quality by design (QbD).

The vast majority of biotherapeutics are parenteral drugs — many of them lyophilized and reconstituted, some shipped and stored as liquid formulations. High-concentration formulations are the industry’s way of delivering large quantities of many protein therapeutics to patients in the least painful and most effective way (1). But such solutions introduce viscosity issues that cause normal delivery methods to be impractical. Using large-diameter needles to deliver drugs isn’t popular with patients, so formulation scientists need to develop other options.

Outsourcing is a big part of the product formulation strategy for most biopharmaceutical companies. But no matter who’s doing the work, the smartest approach is for preformulation work to begin as early as possible in product development. Here, formulators can work hand-in-hand with other laboratory personnel who are characterizing an active molecule for quality and risk-assessment purposes. Their findings can guide downstream formulation development while providing valuable information concerning protein stability, solubility, and structure.

Aggregation and Immunogenicity

One important aspect of that early work is determining what environmental circumstances cause proteins to aggregate and fall out of solution. Aggregation problems have been implicated in adverse reactions and other safety issues since the beginning of clinical applications of protein pharmaceuticals. And antibody aggregates have long been known to cause anaphylactic reactions, so formulations must be optimized to reduce aggregation during storage, handling, and shipping.

Immunogenicity is of increasing concern in formulation development (2, 3). International pharmacopoeias are revising their monographs to improve subvisible particle testing of biotherapeutics and clarify terminologies. In writing my special report on this topic for BPI’s November 2014 issue (4), I found a number of service providers who focus on such testing and discovered new options such as in silico modeling and in vitro bioassays. Many formulators have left behind the tradition of size-exclusion chromatographic detection and quantification of protein aggregation for column-free techniques such as dynamic light scattering, analytical ultracentrifugation, field-flow fractionation, photon-correlation spectroscopy, and microflow imaging.

Stabilizing Drug Products

When aggregation is a problem, you can take steps to prevent it such as incorporating specialized excipients intended to aid in formulation stability (5, 6). Some companies choose freeze-or spray-drying too (7). But even as lot-release testing has diminished somewhat in importance due to risk management and QbD, stability testing is still a vital aspect of formulation development (8). Look for the special report in this month’s regular issue for more on that (9).

Many commercial biotherapeutics are stored frozen either in bulk drug-substance form or after product formulation — either in improvised, stock-purchased, or purpose-designed systems. The choice is often dictated by the volume to be frozen, available technologies, shipment needs, stability of the frozen matrix, and so on.

Freeze-Dried and Particulate Formulations: Lyophilization is a three-stage process: freezing (solidification), primary drying (ice sublimation), and secondary drying (moisture desorption). Dried products need reconstitution: mixing the drug product with a fluid to create an injectable solution. Until fairly recently, that process was up to clinicians and/or clinical pharmacists — or even patients themselves, when managing chronic conditions — and thus involved unwanted risks and variabilities. But newly developed systems for reconstituting and administering injectable formulations are safer, more convenient, and easy to use. Meanwhile, the process of lyophilization itself has improved as companies implement liquid-nitrogen– based cooling systems that increase control over freezing processes and broaden the range of available operating parameters.

In vivo stability is another concern for biological drugs. Sustained release has been a goal for many products with limited in vivo half-lives. One solution is polymeric drug delivery. Lipids and polymers are used to create matrix formulations for sustained delivery — but the better approach to biologics so far appears to be through conjugation rather than formulation. For gene delivery, viruses have had millions of years to perfect their skills, so they so far show more promise than other types of encapsulation. Supercritical fluids and microfluidics have been offered as a means of improving particle-size distribution for inhaled formulations, but so far those have succeeded only with small proteins (e.g., insulin).

Combination products — whether combining small molecules and biologics in one formulation or requiring a specific delivery device — and protein conjugates are presenting new challenges to formulation science (10, 11). They introduce new characteristics and requirements, new degradation pathways, and new excipients.

The addition of polyethylene glycol to formulations is nothing new — but conjugating it to the therapeutic protein itself is (12). The process improves that active molecule’s life in vivo, but it may create instabilities in formulation and problems with immunogenicity that must be dealt with. Solving one problem can sometimes create more. But that’s what risk management is all about.

Fill and Finish

Maintaining the sterility and quality of biologic products through aseptic fill and finish operations, whether conducted in isolators or cleanrooms, is vital to the bioprocessing industry. Advances in barrier isolation, single-use technologies, automation, and packaging have moved fill and finish operations in line with the FDA’s QbD principles and risk management, especially in contamination monitoring and control.

Filling machines come in a range of configurations and formats, including stainless-steel syringe-type and peristaltic-pump systems. In recent years, single-use technologies have found their way into aseptic processing as well. Several factors influence selection of a filling machine (in addition to footprint, operation, throughput, and cost), including a product’s characteristics (solubility, viscosity, and foaming tendency); vial properties; stoppers or other closure components; sealing; validation, cleaning, and sterilization method.

Packaging: A vial’s or syringe’s construction material is also important. Glass vials, and ampules were traditionally made of USP Type I or II glass. But with product recalls specific to glass breakage and delamination or the presence of glass flakes, some manufacturers sought alternative materials (e.g., cyclic olefin polymers). Familiarity with single-use technologies may be feeding back to making plastics an option for drug product storage and delivery. Changes in component materials and design have helped to make prefilled syringes a fast growing segment of the industry and led to innovations in prefilled designs and mechanisms of action, including microinjection systems.

As in many parts of downstream processing, aseptic filling has benefited from implementation of single-use technologies (13). Gamma-sterilized disposable bags, transfer sets, connectors, and rapid-transfer ports are commercially available and can be sent to a manufacturers for immediate use in aseptic fluid transfer. Cost comparisons and design optimization studies of such technologies with those of traditional materials show favorable results associated with disposables implementation.

Strong consideration must be taken to a product’s sensitivity to heat, light, and chemical contaminants as well as any interaction with packaging and/or container–closure components (leachables and extractables). Lyophilized drugs are sensitive to moisture, so an inadequate seal can allow water and other contaminants to enter a package. Some biopharmaceuticals are sensitive to silicone oil (used to lubricate elastomeric stoppers during fill and finish to facilitate insertion of stoppers into vials). It has been associated with inactivation through nucleation of proteins around oil droplets.

Anticounterfeiting and security measures have increased, especially for products such as pandemic-flu vaccines and high-valued monoclonal antibodies. Advanced systems include multilayerd authentication codes for each dose and/or vial and sophisticated track-and-trace networks for supplies and finished products.

The Outsourcing Option

Many biopharmaceutical companies use contract providers for formulation, fill–finish, and packaging services. When working with a contract provider, a sponsor company should make sure to discuss certain vital points. Key considerations include regulatory compliance, level of automation, and flexibility of scale. Contractual relationships should detail the product’s appearance and physical state (whether a liquid or lyophilized solid), packaging and labeling, and how the product will be stored and administered in the clinic. Sponsors should ensure that batch-record preparation and approval are agreed upon so that their filling schedules are met. (Batch records detail all activities associated with filling: components, volumes, and release assays, as well as any buffer preparation and in-process testing required.) Technical considerations include facility design, a CMO’s validation status, and quality systems (3).

References

1 Kling J. Highly Concentrated Protein Formulations: Finding Solutions for the Next Generation of Parenteral Biologics. BioProcess Int. 12(5) 2014: insert

2 Mire-Sluis A, et al. Analysis and Immunogenic Potential of Aggregates and Particles: A Practical Approach, Part 1. BioProcess Int. 9(10) 2011: 38–47.

3 Mire-Sluis A, et al. Analysis and Immunogenic Potential of Aggregates and Particles: A Practical Approach, Part 2. BioProcess Int. 9(11) 2011: 38–43.

4 Scott C. Unwanted Immunogenicity: From Risk Assessment to Risk Management. BioProcess Int. 12(10) 2014: insert.

5 Maggio ET. Polysorbates, Immunogenicity, and the Totality of the Evidence. BioProcess Int. 10(10) 2012: 44–49.

6 Maggio ET. Biosimilars, Oxidative Damage, and Unwanted Immunogenicity: A Review. BioProcess Int. 11(6) 2013: 28–34.

7 Breit J, DuBose D. Spray-Dry Manufacture of Vaccine Formulations: Enabling New Vaccine Concepts and Delivery Through Particle Engineering. BioProcess Int. 11(9) 2013: S32–S40.

8 Patel J, et al. Stability Considerations for Biopharmaceuticals, Part 1: Overview of Protein and Peptide Degradation Pathways. BioProcess Int. 9(1) 2011: 20–31.

9 Rios M. Product Stability Testing: Developing Methods for New Biologics and Emerging Markets. BioProcess Int. 13(5) 2015: in press.

10 Rios M. Combination Products for Biotherapeutics. BioProcess Int. 9(2) 2011: 27–35.

11 Scott C. Protein Conjugates. BioProcess Int. 8(10) 2010: 28–37

12 Kling J. PEGylation of Biologics: A Multipurpose Solution. BioProcess Int. 11(3) 2013: 35–43.

13 Zambaux J-P, Barry J. PEGylation of Biologics: A Multipurpose Solution. BioProcess Int. 12(5) 2014: 46–53.

Further Reading

Castleman L. Simulating Seal Life with Finite-Element Analysis. BioProcess Int. 13(2) 2015: 30–35.

DeGrazio FL. Increasing Biopharmaceutical Quality Through Packaging Partnerships. BioProcess Int. 8(9) 2010: 16–20.

Evans C, Geiselhart E. Understanding the Patient Journey: A Human-Factors Road Map to Pharmaceutical Delivery Device Development. BioProcess Int. 10(11) 2012: 54–56.

Jenness E, Gupta V. Implementing a Single-Use Solution for Fill-Finish Manufacturing Operations. BioProcess Int. 9(5) 2011: S22–S26.

Lewis EN. How to Hit a Moving Target: Taking a Partnering Approach to Meeting the Analytical Challenges of Biologics Development. BioProcess Int. 11(11) 2013: 42–46.

Lin X, Kang J. Replacing Reverse-Phase Chromatography for Mass Spectrometry: Is Salt-Free Size-Exclusion Chromatography Ready? BioProcess Int. 12(9) 2014: 36–42.

Mattuschka J, Santa-Maria V. A Critical Mission: Clinical Trial Material Storage and Distribution. BioProcess Int. 12(8) 2014: 12–17.

McLeod LD, Montgomery SA, Scott C. Fill and Finish for Biologics. BioProcess Int. 9(6) 2011: 34–46.

Mire-Sluis A, et al. Drug Products for Biological Medicines: Novel Delivery Devices, Challenging Formulations, and Combination Products, Part 1. BioProcess Int. 11(4) 2013: 48–62.

Mire-Sluis A, et al. Drug Products for Biological Medicines: Novel Delivery Devices, Challenging Formulations, and Combination Products, Part 2. BioProcess Int. 11(6) 2013

Palm T, et al. The Importance of the Concentration–Temperature–Viscosity Relationship for Development of Biologics. BioProcess Int. 13(3) 2015: 32–34.

Perkins M. Tunable Half-Life Technology: Redefining the Rules of Drug Dosing Frequency? BioProcess Int. 11(3) 2013: 60–63.

Puri M, et al. Evaluating Freeze–Thaw Processes in Biopharmaceutical Development. BioProcess Int. 13(1) 2015: 34–45.

Reynolds G, Paskiet D. Glass Delamination and Breakage. BioProcess Int. 9(11) 2011: 52–57.

Scott C. Enabling Technologies: Speeding Product Development from Discovery Through Manufacturing. BioProcess Int. 12(2) 2014: 21–27.

Stauss B. Safety, Flexibility, and Efficiency: Preparing for the Future in Filling. BioProcess Int. 10(11) 2012: S14–S19.

Steele A, Arias J. Accounting for the Donnan Effect in Diafiltration Optimization for High-Concentration UFDF Applications. BioProcess Int. 12(1) 2014: 50–54. c

Cheryl Scott is cofounder and senior technical editor, and Maribel Rios is managing editor of BioProcess International.