PublicationDate:August19,1994|doi:10.1021fh1<-1994~056?.ch0ll1
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`Downloadedby174.471.174.222onMarch10,2015Ihttp:/l‘pub5_acs.org
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`Chapter 1
`
`Formulation and Delivery of Proteins
`and Peptides
`
`Design and Development Strategies
`
`Jclfrey L. Clelaudl and Robert Longer‘
`
`‘Pharmaceutical Research and Development, Genentech, Inc., South San
`Francisco, CA 94080
`‘Department of Chemical Engineering, Massachusetts Institute
`of Technology, Cambridge, MA 02139
`
`The success of most peptide and protein drugs is dependent upon the
`delivery of the biologically active form to the site of action.
`In the
`design and development of formlllations to achieve this goal, the
`formulation scientist must consider
`the clinical
`indication,
`pharmacokinetics. toxicity. and physicochemical stability of the drug.
`The development of a stable formulation is a necessary step for each
`new protein or peptide therapeutic. The degradation pathways and
`their impact on stability should be systematically analyzed and
`competing degradation rates must be balanced to arrive at the most
`stable formulation possible. Several routes of administration should
`also be considered and future development of new formulations may
`expand the number of potential options. Formulations for each route
`of administration may be unique and,
`therefore, have special
`requirements.
`In the case of depot formulations, there are many
`potential matrices, each of which has distinct characteristics that affect
`its interactions with the drug and its behavior in vivo. The formulation
`characteristics may have a dramatic impact on the in viva stability of
`the drug as well as the pharmacokinetics and pharmacodynamics. The
`optimization of formulations. the routes of delivery, the design of
`depot systems, and the correlation between physicochernical stability
`and in viva behavior are discussed in detail with recent examples. For
`new biotechnology-derived drugs including nucleic acids (DNA
`vectors and antisense RNA) to reach commercialization, all of the
`issues involved in the design and development of a drug formulation
`must be considered at an early stage of the overall development
`process.
`
`Many aspects of biopharrnaceutical process development have been well studied over
`the past twenty years. Difficulties in fermentation. cell culture, and. to some extent,
`purification and recovery have largely been overcome and these process steps have
`been well characterized for the production of many protein pharmaceuticals.
`However, one important field lags behind these others in its development. The design
`and production of protein and peptide drug formulations is not well developed and
`many of the mechanisms for stabilization and delivery of these drugs have not been
`
`D09’?-6156.’94r'D567—lI]01$U8.l]JlU
`© 1994 Alnerican Chemjml Society
`
`CFAD Exhibit 1045
`1045
`CFAD v. NPS
`CFAD V. NPS
`IPR2015-01093
`IPR2015—O1093
`
`In Formulation and Delivery of Proteins and Peptides; Cleland, .I., et aI..
`ACS Symposium Series: American Chemical Society: Washington, DC‘, I994.
`1
`
`CFAD Exhibit 1024
`
`

`
`2
`
`FORMUI.ATION AND DELIVERY OF PROTEINS AND PEPTIDES
`
`determined. In many cases, companies may initially neglect formulation and stability
`issues, resolving to simply store proteins or peptides in phosphate buffered saline or
`other solutions that have not been optimized for stabilizing the drug. Several
`unknowns still exist when developing a stable dosage form for peptides and proteins.
`Each molecule has its own unique physical and chemical properties which determine
`its in vitro stability. The formulation scientist must also be concerned about the in
`vivo stability of the drug. Thus, the development of successful formulations is
`dependent upon the ability to study both the in vitro and in vivo characteristics of the
`drug as well as its intended application.
`
`Effect of Formulation Design and Delivery on Drug Development
`
`As shown in Figure 1, a formulation scientist is confronted with a complex decision
`in choosing a formulation for delivery of a therapeutic protein or peptide. In the
`literature, the most common discussions of protein and peptide formulations focus on
`the physicochemical stability of these molecules. Indeed, the properties of the drug
`molecule are critical in determining the appropriate formulation for successful
`delivery and stability. The vast majority of the literature on protein and peptide
`formulations describes the degradation pathways for the drug. Many degradation
`pathways have been well characterized and, in some cases, degradation may often be
`predicted from the primary sequence of the protein or peptide (see 1 for examples).
`Once the formulation scientist has found a set of conditions that provide extensive
`stability (>2 year shelf-life), the formulated drug is tested in animal models for
`toxicity and pharmacokinetics. In many cases, this. testing phase does not occur until
`the drug has moved from research into development. At this stage, many problems
`can occur including poor bioavailability due to the instability of the drug in vivo,
`rapid clearance, or the distribution of the drug in the body. Furthermore, an attempt is
`often made to resolve these difficulties by administering excess drug to achieve the
`desired biological effect. However, excessive drug doses often lead to toxicity
`problems. By this stage, the development of the drug has reached a critical decision
`point. The tendency in most organizations is to reconsider the development of the
`drug, sometimes resulting in the 'death' of the development project. However •. the
`formulation scientist has the unique opportunity to work with the scientists in
`pharmacokinetics and toxicology to 'save' the development of the drug. By altering
`the formulation or the route of delivery, a drug can often have another opportunity to
`reach the stage of an Investigational New Drug (IND) filing. Unfortunately, the
`formulation scientist may not become involved until the drug has already encountered
`difficulties in animal studies. Thus, it is essential for the formulation scientist to work
`closely with the discovery research team, the pharmacokinetics department, and the
`toxicology department prior to the decision to move the drug into full scale
`development.
`
`After all the difficulties are resolved in the early development stages, many protein
`and peptide drugs can still encounter problems in the clinic. The major clinical
`hurdles may be similar to those observed in the pre-IND animal studies. However,
`the company may have filed an IND for a therapeutic indication that will encounter
`complex formulation and delivery problems. The route and frequency of
`administration and the bioactivity or potency of the drug in humans are critical issues
`that are often not addressed in the pre-IND animal studies. If difficulties in delivery
`or potency of the drug arise during clinical trials, the formulation scientist along with
`others on the development team must reconsider the design of both the drug
`formulation and the clinical plan. These pitfalls may often be avoided by testing the
`drug in a suitable animal model, if available, and an extensive analysis of the patient
`population including a marketing survey of the end users (physicians, nurses, and/or
`patients). By establishing early in the development stage (e.g. between research and
`Phase I clinical trials) the best route and formulation for the drug, the potential for a
`
`In Formulation and Delivery of Proteins and Peptides; Cleland, J., et al.;
`ACS Symposium Series; American Chemical Society: Washington, DC, 1994.
`2
`
`

`
`1. CLELAND AND I.ANGER Design and Development Strategies
`
`3
`
`Physicochemical
`Properties of Drug
`
`•In Vivo
`and
`In Vitro
`Stability
`
`• _Biological
`Function
`•Potency
`
`Phannacokinetics
`& Toxicity
`
`__ .._,
`
`Clinical Indications
`(Acute/Chronic)
`
`Figure 1: Key factors influencing the design of drug formulations and delivery. The
`physicochemical properties of the drug can affect the pharmacokinetics and toxicity
`as well as the clinical indication. The in vitro and in vivo stability of the drug
`determines its fate upon administration. The potential clinical utility of the drug is
`dependent upon the drug characteristics, biological function, and potency. To obtain
`the desired pharmocological response, a drug must be administered with a stable
`formulation. The design of a delivery system must also consider the clinical
`indication, pharmacokinetics, pharmacodynamics, toxicology, and drug properties.
`
`In Formulation and Delivery of Proteins and Peptides; Cleland, J., et al.;
`ACS Symposium Series; American Chemical Society: Washington, DC, 1994.
`3
`
`

`
`4
`
`FORMUIATION AND DELIVERY OF PROTEINS AND PEPTIDES
`
`clinically successful product and, ultimately, a marketed product increases
`dramatically.
`
`The best route for delivery of a protein or peptide drug is often not investigated
`during the research stage or early in development. The protein or peptide is
`commonly administered systemically through an intravenous (i.v.) injection in initial
`animal testing. Thus, for indications that require a high local dose of the drug at the
`target site, high drug doses are required by i.v. injections. Due to toxicity problems,
`the efficacious dose may not be reached via i.v. administration. More recently,
`alternative routes of delivery have been studied. In particular, the therapeutic protein,
`recombinant human deoxyribonuclease I (rhDNAse), must be delivered directly to the
`lung of cystic fibrosis patients to degrade the DNA in the mucus. rhDNAse delivered
`systemically would clearly have little effect on the target site. While this example is
`an obvious candidate for an alternate delivery route (aerosol delivery of rhDNAse),
`many other proteins and peptides may also benefit from alternative routes of delivery
`for therapeutic or clinical reasons. It is therefore essential to investigate the site of
`action and assess any side effects before choosing a route of administration.
`
`In addition, when companies are developing competitive products, the future sales of
`the product may rest upon the superior formulation and delivery of the drug,
`assuming that the efficacy of the competing products are similar. For example, many
`existing therapeutic proteins such as human growth hormone and insulin are
`administered chronically requiring daily injections. Competitors with superior drug
`formulations that release a sustained level of the protein and, thus, require less
`frequent injections would dominate the market. An example of competing products is
`the development of sustained release formulations for a luteini~ing hormone-releasing
`hormone (LHRH) agonists. Takeda Pharmaceuticals developed an LHRH agonist
`(leuprolide acetate) - polylactide-coglycolide formulation that could be administered
`monthly and provided a continuous sustained therapeutic level of LHRH for one
`month (2-5). This product, Lupron Depot®, had a ¥57 billion (-$570 million) market
`in 1992 for prostate cancer, precocious puberty and endometriosis indications and
`competition from other types of LHRH agonist formulations, including daily
`injections and daily nasal delivery, have been insignificant (6). Similar competitive
`products also consist of controlled release systems using polylactide-coglycolide with
`different LHRH agonists (goserelin acetate, Zoladex®, 7, triptorelin, Decapeptyl®,
`8). Overall, the clinical administration, patient compliance, pharmacokinetics,
`toxicity, and physicochemical properties of the drug must be considered to
`successfully develop a pharmaceutical protein or peptide drug.
`
`Formulation Development Considerations
`
`While development of novel delivery routes or systems is often necessarY,, the first
`step in development of any protein or peptide drug formulation involves the, complete
`characterization of the drug properties and its stability in different formulations.
`Typically, a formulation scientist will begin by considering the physicochemical
`properties of the protein such as the isoelectric point, molecular weight, glyeosylation
`or other post-translational modification, and overall amino acid composition. These
`properties along with any known behavior of the drug in different solutions (e.g.
`different buffers, cofactors, etc.) as well as its in vivo behavior should guide the
`choice of formulation components for testing in the initial screen of candidate
`formulations. The potential candidate formulations are composed of U. S. ·Food and
`Drug Administration (FDA) approved buffer components, excipients,' and any
`required cofactors (e.g. metal ions). Often, the first choice of candidate formulations
`is based upon the previous experience of the formulation scientist with other proteins
`
`In Formulation and Delivery of Proteins and Peptides; Cleland, J., et al.;
`ACS Symposium Series; American Chemical Society: Washington, DC, 1994.
`4
`
`

`
`1. CLELAND AND IANGER Design and Develop111£111 Strategies
`
`5
`
`or peptides and, in many cases, a simple phosphate buffered saline solution may be
`one of the initial candidates.
`
`A simplified approach to formulation development may proceed through the steps
`depicted in Figure 2. After obtaining all the available background information, one
`often evaluates several parameters in the initial screen of candidate formulations.
`One parameter that impacts all the major degradation pathways is the solution pH.
`Thus, the initial formulations also assess the pH dependence of the degradation
`reactions and the mechanism for degradation can often be determined from the pH
`dependence (9). The formulation scientist must quickly analyze the stability of the
`protein in each solution. Rapid screening methods usually involve the use of
`accelerated stability at elevated temperatures (e.g. 40° C; see references 10-13 for
`discussions of elevated temperature studies). Unfortunately, the FDA will only
`accept real time stability data for shelf life and accelerated stability studies may only
`serve as a tool for formulation screening and stability issues related to shipping or
`storage at room temperature. The degradation of the protein for both accelerated and
`real time studies is then followed by assays developed for analysis of degradation
`products (see reference 14 for detailed review). The most common degradation
`pathways for proteins and peptides are listed in Table I. Several recent reviews have
`analyzed these pathways as well as potential methods to prevent degradation (11, 15-
`18). In each case, the amount of degradation must be minimized to achieve greater
`than or equal to 90% of the original drug composition after 2 years (e.g. t 90 ~ 2
`years). The FDA usually requires that a pharmaceutical product is not more than 10%
`degraded and the company must demonstrate that the degradation products do not
`have any adverse effects on the safety or efficacy of the drug. Many proteins and
`peptides can degrade extensively without effecting either their safety or efficacy. For
`example, 70% deamidated recombinant human growth hormone (rhGH) is fully
`bioactive and non-immunogenic, but this extent of degradation is not acceptable by
`regulatory agency standards for a therapeutic protein (J 9). The effect of degradation
`on the safety and efficacy of a protein or peptide is difficult to ascertain without
`extensive testing. Thus, the more conservative standards of the FDA and other
`regulatory agencies may often provide a less expensive alternative if a stable
`formulation(> 2 year shelf-life) can be developed.
`
`To fulfill the regulatory requirements for a stable formulation, the scientist must
`consider all of the major degradation routes and the potential conditions for
`optimization. In the case of aggregation, the addition of surfactants or sugars can
`prevent denaturation events that lead to irreversible aggregation. If the deamidation
`rate is the dominant degradation route, the use of amine buffers such as Tris,
`ammonium, or imidazole may slow the deamidation. Alternatively, a reduction in pH
`will also decrease the deamidation rate, but the reduced pH may also lead to cleavage
`or cyclization at Asp-X residues where Xis usually a residue with a small side chain
`(e.g. Gly or Ser) and this degradation has been observed in several proteins (J).
`Proteins with Asp-X degradation must then be placed in a higher pH buffer to avoid
`cleavage or cyclization. High pH conditions (> pH 8) will however catalyze
`oxidation, thiol disulfide exchange, and p-elimination reactions. These degradation
`pathways may be inhibited by the addition of free radical and thiol scavengers such as
`methionine. In addition, the method used to prevent one type of degradation may
`influence another degradation pathway. For example, by adding surfactants or other
`polymers to prevent aggregation, the residual peroxide in the surfactant may cause a
`more rapid oxidation (20). In some cases, the formulation pH must be reduced to
`decrease the rate of deamidation. Reducing the pH may also alter the solubility of the
`protein since many proteins have isoelectric points at or near the optimal pH (pH 5-6)
`for minimizing the deamidation rate. For each protein formulation, all the
`degradation pathways must be evaluated and often a balance must be achieved
`between the different degradation pathways.
`
`In Formulation and Delivery of Proteins and Peptides; Cleland, J., et al.;
`ACS Symposium Series; American Chemical Society: Washington, DC, 1994.
`5
`
`

`
`6
`
`FORMULATION AND DELIVERY OF PROTEINS AND PEPTIDES
`
`Protein or Peptide Drug
`Candidate lndentified
`
`hysicochemical Properties
`(pl, MW, composition,
`solution behavior, etc.)
`
`In Vivo Information
`(site of action, clinical
`application, toxicity,
`pharmacokinetics)
`
`Choose initial formulations
`and perform elevated T
`stability studies (liquid).
`
`Determine major degradation routes.
`
`Ai:mi:ation
`- Add surfactants
`- Alter buffer conditions
`or add other excipients
`to increase solubility
`
`Oxidation
`- Remove headspace 02
`- Remove excipients with
`oxidizing agents
`- Add antioxidants
`
`Deamidation
`- Change buffer to reduce rate
`Tris> NH3 > imidazole - C032- > H2P04"
`Slow rate -----------> Fast rate
`- Reduce pH to 4-5.
`Thiol Disulfide Exchani:e and a Elimination
`
`Aspartate Reactions
`- H Asp-Pro cleavage, raise pH.
`- H Asp-X cyclization, raise pH.
`
`- Reduce pH, remove metals, remove oxidizing
`excipients, add thiol scavengers or antioxidants.
`
`Balance Competing Degradation Pathways
`or Consider Lyophilization
`
`I Lyophilizationl
`Aggregation
`Oxidation
`- Reduce 0 2
`- Lyoprotectants
`- Cryprotectants
`- Surface area
`- Surface area
`- Residual moisture
`
`Screen next round of formulations
`1------~..t - Accelerated stability at elevated T
`
`No
`
`Figure 2: Simplified process diagram for formulation development (See Table I and
`text for detailed discussion).
`
`In Formulation and Delivery of Proteins and Peptides; Cleland, J., et al.;
`ACS Symposium Series; American Chemical Society: Washington, DC, 1994.
`6
`
`

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`
`1. CLELAND AND LANGER Design and Development Strategies
`
`7
`
`Table I: Common Degradation Routes for Proteins and Peptides in Aqueous
`Solutions a
`
`Degradation Route Region Effected/Results
`
`Major Factors
`
`Aggregation
`
`Whole protein; reversible or
`irreversible self-association
`
`Shear, surface area,
`surfactants, pH, T,
`buffers, ionic strength
`
`Deamidation
`
`Asn or Gln; acidic product,
`isoform, or hydrolysis
`
`pH, T, buffers
`ionic strength
`
`Isomerization/
`Cyclization
`
`Asn-X, Asp-X (X= Gly or Ser);
`basic product
`
`pH, T, buffers
`ionic strength
`
`Cleavage
`
`Oxidation
`
`Asp-X; fragments
`(proteolysis also possible from
`trace proteases)
`
`Met, Cys, His, Trp, Tyr;
`oxidized forms
`
`pH, T, buffers
`
`Oxygen {ions, radicals,
`peroxide), light, pH, T,
`buffers, metals,
`{surfactants), free radical
`scavengers
`
`Thiol Disulfide
`Exchange
`
`Cys; mixed disulfides:
`intermolecular or intramolecular
`
`pH, T, buffers, metals,
`thiol scavengers
`
`~ Elimination
`
`Cys; dehydroalanine, free
`thiol
`
`pH, T, buffers, oxygen
`{ions, radicals, peroxide),
`metals
`
`a This table lists degradation pathways commonly observed for proteins and peptides.
`However, this list is not comprehensive and many of these degradation routes may
`occur independently or in combination with one another.
`
`In Formulation and Delivery of Proteins and Peptides; Cleland, J., et al.;
`ACS Symposium Series; American Chemical Society: Washington, DC, 1994.
`7
`
`

`
`8
`
`FORMULATION AND DELIVERY OF PROTEINS AND PEPTIDES
`
`The formulation scientist also has the option of developing a solid formulation such
`as a lyophilized powder. The removal of excess water from the formulation
`minimizes the degradation rates for deamidation and hydrolysis. The residual
`moisture in a solid protein or peptide formulation can contribute to the physical
`stability of the protein by preventing its denaturation and subsequent aggregation
`upon reconstitution. Recent studies on lyophilization of proteins have shown that in
`the absence of excipients, proteins require some residual water, usually referred to as
`bound water, for stability (21). In the presence of excipients such as sugars, the
`amount of remaining water may often be reduced to levels below the hydration layer
`(22). Two different theories are currently used to explain the excipient stabilization
`of proteins and peptides in the lyophilized state. The first theory is based upon the
`observed differences in crystallinity for each excipient in the dry state. The major
`differences in each excipient have been correlated to their glass transition temperature
`(23). This theory neglects the specific interactions between excipients during drying
`and in the final dried state. The second theory, often referred to as the water
`replacement hypothesis, contends that some excipients can substitute for water in the
`dried state and thereby provide stabilization (24, 25). However, this theory also has
`its faults since many excipients with similar hydrogen bonding characteristics provide
`different degrees of stabilization (e.g. mannitol versus trehalose). Recent work by
`Carpenter and coworkers has demonstrated that there may be two distinct
`mechanisms for excipient stabilization. These mechanisms include protection during
`freezing (cryoprotectants) and drying (lyoprotectants) (26). The specific interactions
`between proteins and excipients with these properties have not yet been determined,
`but it is probable that an understanding of these interactions will lead to more rational
`design of solid protein and peptide formulations. While these studies focus on the
`prevention of denaturation and aggregation of proteins in the lyophilized state, other
`degradation routes are also critical for solid protein and peptide formulations. For
`example, residual oxygen head space in a vial containing the solid formulation can
`affect the rate of oxidation (22). Therefore, the degradation issues for lyophilized
`formulations are comparable to liquid formulations, but deamidation and hydrolysis
`rates are usually slower in the solid state.
`
`Once the decision has been made to narrow the formulation candidates or proceed
`with a lyophilized formulation, another round of screening at elevated temperatures is
`usually performed. If these studies account for the potential differences between real
`time data at the actual storage conditions (usually 2-8° C) as described elsewhere (10-
`13), then the formulation scientist can select two or three final candidate formulations
`that should have a greater than 2 year shelf-life for real time stability studies.
`Unfortunately, the formulation scientist is often asked to have a stable formulation
`within a very short time (< 6 months). Thus, the real time stability data is often
`limited, but these data are required for the IND filing since the FDA will not accept
`any accelerated stability data. Stability problems encountered later are treated as
`amendments during the clinical trials. Further changes after the IND filing may
`include scale-up of the manufacturing process including the formulation. The scale(cid:173)
`up of formulations may include new processing and storage containers, bulk filling
`equipment, and new delivery systems or vial confiqurations. These modifications
`may require another evaluation of the formulation with additional optimization.
`Hopefully, any necessary changes in the formulation already in clinical trials will not
`alter the in vivo characteristics of the drug (e.g. clearance, immunogenicity or
`potency).
`
`The Crucial Steps in Delivery
`
`While considering the alternatives for formulating a protein or peptide drug, the
`formulation scientist must also consider the route of administration. As mentioned
`
`In Fommlation and Delivery of Proteins and Peptides; Cleland, J., et al.;
`ACS Symposium Series; American Chemical Society: Washington, DC, 1994.
`8
`
`

`
`1. CLELAND AND LANGER Design and Development Strategies
`
`previously, the route of administration can often be a critical variable in determining
`the success of the final product. As shown in Table II, there are many potential routes
`for the delivery of protein or peptide drugs. For proteins, only the direct injection and
`pulmonary routes of delivery have been approved by the FDA. Due to their large
`size, susceptibility to proteolytic degradation and requirements for an intact tertiary
`structure, proteins are difficult to deliver by oral, topical, or transdermal routes. Oral
`delivery of peptides and proteins usually results in low bioavailability ( < 10%) and
`attempts to make stable prodrugs of peptides, which are more readily absorbed have
`provided some increase in the bioavailability (28). Unlike oral delivery, topical and
`transdermal delivery routes may be efficient enough for a localized treatment of skin
`disorders or diseases and, perhaps, for other localized therapies. Another method for
`protein delivery is the use of depot systems. Several companies are investigating
`their potential application. The depot systems offer the opportunity to localize the
`drug to the target site, reduce the frequency of injections, extend the half-life of the
`drug, and enhance its in vivo stability. Unfortunately, these systems also have
`inherent disadvantages that have not yet been overcome for their successful
`development into commercial products. A major disadvantage is often the use of
`harsh conditions (e.g. organic solvents or high temperature) to produce the depot,
`In addition, for a long term depot
`resulting in denaturation of the protein (29).
`formulation, the protein must be stabilized in an aqueous environment under
`physiological conditions at 37° C. Significant degradation has been observed for
`proteins stored under conditions analogous to those encountered in the depot (30, 31).
`For most of the novel delivery routes or depot formulations, the environment at the
`site of administration must be considered and stability studies of the drug in the same
`environment (e.g. serum) should be performed to assure that complete degradation
`does not occur before the drug reaches the desired site of action (32). Thus, the
`successful development of these formulations requires the initial development of
`protein formulations that are stable to both the process conditions and the in vivo
`environment.
`
`Design of Depot Systems for Delivery. After the development of a formulation that
`meets these criteria, the material for the depot system must be chosen. The material
`should be biodegradable, well characterized, and nontoxic. The depot should also
`not alter the pharmacological properties of the drug and should act only as an inert
`carrier. Several examples of materials tested for depot systems are listed in Table ill.
`While the materials derived from natural sources may often be more biocompatible,
`these materials may vary in their physical characteristics and can be difficult to obtain
`· in a highly purified form. Many of the natural materials are derived from
`recombinant or animal sources and may contain contaminants such as endotoxins. In
`addition, some natural materials such as collagen or other proteins may invoke an
`unwanted immune response. In contrast, the synthetic materials are usually well
`characterized, highly pure polymers. The synthetic polymers have different physical
`and chemical characteristics. The polyanhydrides, polyesters, polyiminocarbonates,
`and polycaprolactones require the use of organic solvents or high temperatures for
`drug formulation. These systems are however well characterized and can be made
`reproducibly. On the other hand, the hydrogels, polyamino acids, and
`polyphosphazenes can be used to encapsulated drugs in an aqueous environment
`without organic solvents or elevated temperatures. These polymers are usually less
`stable and additional development is required to completely characterize their
`properties for controlled release of proteins and peptides. Of the synthetic materials,
`only the polyesters, specifically polylactic-coglycolic acid (PLGA) and polylactic
`acid (PLA), are currently used in commercial depot systems, Lupron Depot®(2-5)
`and Zoladex® (58, 59). These products were recently approved as alternate
`formulations and the polymer matrix, PLGA, has been well characterized and has
`been used extensively in humans. These polymers have been used for over twenty
`
`In Formulation and Delivery of Proteins and Peptides; Cleland, J., et al.;
`ACS Symposium Series; American Chemical Society: Washington, DC, 1994.
`9
`
`

`
`10
`
`FORMULATION AND DELIVERY OF PROTEINS AND PEPTIDES
`
`Table II: Routes of Delivery for Proteins and Peptides
`
`Delivery Routes
`
`Formulation and Device
`Requirements
`
`Commercial
`Productsa
`
`Invasive
`
`Direct Injection
`
`Liquid or reconstituted solid, syringe
`
`intravenous (i. v.)
`subcutaneous (s.q.)
`intramuscular (i.m.)
`intracerebral vein (i.c.v.)
`
`Depot system
`
`Biodegradable polymers, liposomes
`permeable polymers (not degradable),
`microspheres, implants
`
`LHRH analogs (s.q. or i.m.)
`
`Noninvasive (see reference27 for review)
`
`Activase®
`Nutropin®
`RecombiVax®
`
`Lupron Depot®
`Zoladex®
`Decapeptyl®
`
`Pulmozyme®
`
`Pulmonary
`
`Oral
`
`Nasal
`
`Topical
`
`Transdermal
`
`Liquid or powder formulations,
`nebulizers, metered dose inhalers,
`dry powder inhalers
`
`Solid, emulsion, microparticulates,
`absorption enhancers
`
`Liquid, usually requires permeation
`enhancers
`
`Synarel®
`
`Emulsion, cream or paste (liposomes)
`
`Electrophoretic (iontophoresis ),
`electroporation, chemical permeation
`enhancers, prodrugs, ultrasonic
`
`Buccal, Rectal, Vaginal
`
`Gels, suppositories, bioadhesives, particles
`
`a Nutropin® (recombinant human growth hormone), Activase® (recombinant human
`tissue plasminogen activator), and Pulmozyme® (recombinant human deoxyribo(cid:173)
`nuclease I) are all products of Genentech, Inc. RecombiVax® (recombinant
`Hepatitis B surface antigen) is produced by Merck & Co. Lupron Depot®
`(leuprolide acetate - PLGA) is a product of Takeda Pharmaceuticals. Zoladex®
`(goserelin acetate - PLGA) is produced by the Imperial Chemical Industries, Ltd.
`Decapeptyl® is a manufactured by Debiopharm. Synarel® (nafarelin acetate) is
`made by Syntex Corporation.
`
`In Formulation and Delivery of Proteins and Peptides; Cleland, J., et al.;
`ACS Symposium Series; American Chemical Society: Washington, DC, 1994.
`10
`
`

`
`1. CLELAND AND LANGER Design and Development Strategies
`
`11
`
`Table ID. Biodegradable Materials for Controlled Delivery of Proteins or
`Peptides
`
`Materials
`
`Degradation Mechanism
`
`Reference a
`
`Natural
`
`Starch
`
`Alginate b
`
`Collagen
`(Gelatin)
`
`Amylase
`
`pH, Enzymes
`
`Collagenase
`
`Proteins
`(Cross-linked albumin)
`
`Enzymes
`
`Tricalcium phosphate c
`or calcium carbonate
`(hydroxyapatite)
`
`Dissolves over time
`
`Synthetic
`
`Hydro gels
`
`Polyanhydrides
`
`Polyesters
`(polylactides)
`
`Chemical or enzymatic hydrolysis,
`solubilization in aqueous media
`
`Hydrolysis
`
`Ester hydrolysis, esterases
`
`Poly (ortho esters)
`
`Ester hydrolysis, esterases
`
`Polyiminocarbonates
`
`Hydrolysis
`
`Polycaprolactones
`
`Polyamino acids
`
`Hydrolysis
`
`Enzymes
`
`Polyphosphazenes b
`
`Hydrolysis, dissolution
`
`33,34
`
`35,36
`
`37-39
`
`40,41
`
`42-44
`
`45
`
`46-48
`
`49,50
`
`49
`
`51,52
`
`53,54
`
`55
`
`56,57
`
`a Reviews describing