List of Excipients in Branded Drug BONSITY

Company	Tradename	Ingredient	NDC	Excipient	Potential Generic Entry
Alvogen Inc	BONSITY	teriparatide	47781-852	ACETIC ACID
Alvogen Inc	BONSITY	teriparatide	47781-852	MANNITOL
Alvogen Inc	BONSITY	teriparatide	47781-852	METACRESOL
Alvogen Inc	BONSITY	teriparatide	47781-852	SODIUM ACETATE
Alvogen Inc	BONSITY	teriparatide	47781-852	WATER

BONSITY Excipient Strategy and Commercial Opportunities

Last updated: August 16, 2026

BONSITY is a teriparatide injection approved by the FDA in 2019 through the 505(b)(2) pathway. Its commercial differentiation depends less on a new active ingredient than on formulation execution, delivery-device usability, regulatory bridging, and access to the osteoporosis market after loss of exclusivity for FORTEO. The product’s excipient system supports peptide stability, isotonicity, antimicrobial preservation, and subcutaneous administration, but the main commercial opportunity is a lower-cost or more accessible teriparatide alternative rather than a broad excipient-based patent moat.

What is BONSITY and how is it regulated?

BONSITY is a recombinant human parathyroid hormone fragment, teriparatide, administered by subcutaneous injection. It is indicated for postmenopausal women with osteoporosis at high fracture risk, men with primary or hypogonadal osteoporosis at high fracture risk, and adults with glucocorticoid-induced osteoporosis at high fracture risk.

Attribute	BONSITY
Active ingredient	Teriparatide
Dosage form	Sterile injectable solution
Strength	250 mcg/mL
Route	Subcutaneous
FDA pathway	505(b)(2)
NDA	NDA 212553
Approval	October 4, 2019
Commercial sponsor	Radius Health, Inc.
Reference product context	FORTEO
Dose	20 mcg once daily
Maximum treatment duration	Generally two years over a patient’s lifetime
Storage	Refrigerated before and during use
Post-opening use	Pen is discarded after 28 days
FDA status	Approved prescription drug

The 505(b)(2) pathway allowed Radius to rely partly on FDA findings for an already approved teriparatide product while supporting differences in formulation, device, manufacturing, or labeling through additional data submitted in the BONSITY application (U.S. Food and Drug Administration [FDA], 2019a).

BONSITY is not a biosimilar. Teriparatide is a synthetic or recombinant peptide drug, and the product is regulated under an NDA rather than an abbreviated biologics license application. Future competitors may pursue an ANDA if FDA determines that the relevant criteria for a generic injectable product are met, or a 505(b)(2) application if the product has meaningful formulation, device, or clinical differences.

What excipients are used in BONSITY?

BONSITY contains a conventional acidic peptide-injection excipient system. The FDA prescribing information identifies the following inactive ingredients:

Excipient	Primary formulation function
Glacial acetic acid	Acidification and pH adjustment
Sodium acetate trihydrate	Acetate buffering
Mannitol	Tonicity adjustment and bulking agent
Metacresol	Antimicrobial preservative
Water for injection	Vehicle

The product has an acidic formulation with a target pH range of approximately 3.8 to 4.5. The formulation is supplied in a multidose prefilled delivery system and is intended for repeated daily administration over the usable life of the pen (FDA, 2019b).

Why the BONSITY excipient system matters

Teriparatide is a peptide and is susceptible to degradation pathways that can affect potency, purity, aggregation, and visible or subvisible particle levels. The BONSITY formulation addresses several practical requirements:

1. Acidic pH control can support peptide stability.
2. The acetate system provides buffering capacity during storage and administration.
3. Mannitol helps manage osmolality and injection tolerability.
4. Metacresol permits multidose use without repeated microbial contamination of the cartridge.
5. The aqueous vehicle supports immediate-use subcutaneous delivery without reconstitution.

The excipients are individually well known. The commercial value lies in their concentration ranges, interaction with teriparatide, preservative performance, container closure, device compatibility, and stability profile. A formulation patent would generally need to claim a defined combination or performance characteristic rather than the mere presence of acetate, mannitol, or metacresol.

How does BONSITY compare with FORTEO?

BONSITY and FORTEO use the same active peptide and the same 20 mcg daily dose, but they are not necessarily interchangeable at the pharmacy level solely because they contain teriparatide. Interchangeability depends on FDA product-specific determinations and state substitution rules.

Commercial factor	BONSITY	FORTEO
Active ingredient	Teriparatide	Teriparatide
Administration	Daily subcutaneous injection	Daily subcutaneous injection
Regulatory origin	505(b)(2) product	Original NDA product
Product position	Alternative teriparatide product	Reference brand
Excipient strategy	Acetate buffer, mannitol, metacresol, water	Teriparatide formulation with established multidose pen
Main differentiation	Potential price, access, device and supply positioning	Brand recognition, clinical history and market access
Biosimilar status	Not applicable	Not applicable
Commercial vulnerability	Price competition and limited duration of therapy	Generic and alternative teriparatide competition

BONSITY’s competitive value is strongest where payers, specialty pharmacies, and health systems want an alternative to FORTEO but still require a familiar daily peptide injection. The product does not create a new treatment segment. It competes for the existing anabolic osteoporosis market.

What excipient strategy protects BONSITY?

The disclosed excipients alone are unlikely to create a durable barrier to entry. A competitor can generally use the same classes of excipients if it develops an acceptable formulation and clears FDA requirements. Protection may instead arise from a combination of:

• Specific acetate concentration and pH range.
• Teriparatide concentration and peptide-to-excipient ratio.
• Preservative concentration and antimicrobial effectiveness.
• Long-term and in-use stability.
• Low aggregate or degradation-product levels.
• Compatibility with the multidose cartridge.
• Device performance after repeated needle punctures.
• Delivered-dose accuracy over 28 days.
• Manufacturing controls for peptide adsorption and oxidation.

A formulation patent can be commercially useful if it claims a narrow combination that solves a measurable problem, such as improved stability, reduced degradation, or improved compatibility with a multidose injection device. Its strength depends on whether the claims cover commercially necessary concentrations or only a narrow laboratory range.

What formulations could competing companies develop?

Potential competitive formulations include:

1. Preservative-free single-dose pens or cartridges.
2. Alternative preservatives for patients with metacresol sensitivity.
3. More concentrated teriparatide solutions that reduce injection volume.
4. Longer in-use stability periods.
5. Room-temperature-stable products.
6. Prefilled syringes or autoinjectors.
7. Needle-free or low-force delivery systems.
8. Combination products that pair teriparatide with adherence-support technology.

Each modification creates a regulatory and technical tradeoff. Removing metacresol may improve tolerability for selected patients but can complicate multidose sterility. Increasing concentration may reduce injection volume but raise aggregation, adsorption, or local tolerability concerns. Extending room-temperature stability could have greater commercial value than a minor change in buffer composition because it directly addresses patient handling and distribution costs.

When does BONSITY lose exclusivity?

BONSITY does not have the same remaining exclusivity profile as an original biologic or a newly discovered small molecule. Teriparatide’s foundational composition and product exclusivity protections are largely historical. The product’s commercial protection depends on the specific patents listed for BONSITY, regulatory exclusivity, formulation and device rights, and any litigation settlements.

Exclusivity category	BONSITY position
New chemical entity exclusivity	Not applicable to the established teriparatide active ingredient
Orphan-drug exclusivity	Not applicable
Pediatric exclusivity	No broadly relevant standalone period identified in the core approval record
505(b)(2) exclusivity	Must be assessed from the FDA approval record and listed patents
Formulation patents	Potentially relevant, but claim scope and status require patent-by-patent review
Device patents	Potentially relevant to the injection pen
Method-of-use patents	Possible, but treatment duration and osteoporosis indications are mature
Orange Book patents	Must be checked against the current FDA listing

The precise loss-of-exclusivity date cannot be stated from the approval date alone. The relevant dates are the expiration dates of patents listed for NDA 212553, any patent-term adjustment or extension, and the effect of Paragraph IV litigation. The FDA Orange Book is the controlling public source for currently listed patents and pediatric exclusivity information (FDA, n.d.-a).

What is the Orange Book status of BONSITY?

BONSITY is an NDA product and therefore can have patents listed in the FDA Orange Book. Orange Book review should focus on:

• Product patents covering the teriparatide formulation.
• Drug-delivery-system patents.
• Method-of-use patents.
• Patent expiration dates.
• Delisting events.
• Paragraph IV certifications filed by ANDA applicants.
• Thirty-month stays triggered by patent litigation.

Orange Book listing does not establish that a patent is valid or infringed. It indicates that the NDA holder has submitted patent information that FDA has accepted for listing under applicable regulations. A competitor can challenge listed patents through Paragraph IV certification, invalidity arguments, non-infringement positions, or a 505(b)(2) application with a patent certification.

Which companies are challenging BONSITY?

Publicly identifying challengers requires current FDA Orange Book data, ANDA litigation dockets, and Paragraph IV notices. The principal likely challenger categories are:

• Generic injectable manufacturers.
• Specialty pharmaceutical companies with osteoporosis portfolios.
• Contract development and manufacturing organizations partnering with ANDA sponsors.
• Device companies seeking to commercialize a lower-cost teriparatide pen.

A Paragraph IV challenge against a BONSITY patent would create a potential early-entry pathway. The NDA holder could sue within 45 days of receiving notice, triggering a statutory stay of ANDA approval for up to 30 months, subject to court and regulatory events under the Hatch-Waxman framework.

No litigation or settlement conclusion should be inferred from the existence of an Orange Book listing. The relevant analysis requires docket-level review of district court complaints, Federal Circuit appeals, settlement terms, and any authorized-generic arrangements.

What patent litigation affects BONSITY?

The central litigation risks are likely to involve four issues:

Formulation patent validity

A challenger may argue that the claimed excipient combination was obvious in view of prior teriparatide formulations, peptide-injection references, or routine buffer and preservative optimization.

Written description and enablement

Claims covering broad concentration ranges can face written-description and enablement challenges if the specification does not demonstrate the full claimed scope.

Device patent infringement

A competing pen may avoid infringement by changing cartridge geometry, dose-delivery mechanics, needle attachment, or user-interface elements.

Method-of-use scope

Osteoporosis dosing and treatment-duration claims may be vulnerable if they overlap with established clinical practice or if a competitor uses a skinny-label strategy that omits patented indications.

Settlement agreements may provide an agreed generic launch date, authorized-generic rights, supply obligations, or restrictions on formulation and device substitution. These terms are commercially material but are not reliably summarized by patent expiration dates alone.

How strong is the BONSITY patent estate?

BONSITY’s patent estate should be viewed as moderate at best unless it includes broad, enforceable formulation or device claims with expiration dates extending well beyond the basic teriparatide patents.

Estate component	Likely strength
Teriparatide composition claims	Weak as a current barrier because the active ingredient is mature
Basic injectable formulation claims	Moderate to weak because common excipients are widely known
Narrow stability claims	Moderate if supported by comparative data
Multidose pen claims	Moderate if design-specific and difficult to design around
Broad method-of-use claims	Weak to moderate in a mature indication
Manufacturing claims	Moderate where peptide purity and scale-up controls are difficult to replicate
Trade secrets	Potentially important for process parameters, analytics and fill-finish controls

The most defensible assets may be manufacturing know-how and device integration rather than the disclosed excipients. Regulatory comparability can also create a practical barrier even when formal patent protection is limited. A competitor must demonstrate acceptable peptide quality, sterility assurance, delivered-dose accuracy, stability, and device reliability.

What commercial opportunities exist for BONSITY?

BONSITY has five principal commercial opportunities.

Lower-cost anabolic osteoporosis treatment

Teriparatide is used in patients at high fracture risk, including those who need an anabolic treatment before antiresorptive maintenance therapy. A lower-priced alternative can expand access where FORTEO cost or formulary restrictions limit use.

Payer and specialty-pharmacy contracting

The product can compete through preferred formulary status, rebates, specialty-pharmacy distribution, and simplified prior authorization. Contracting is likely to have greater impact than small changes in excipient composition.

Device-led adherence

Daily injections create an adherence burden. A simpler pen, lower injection force, improved dose confirmation, or better patient training could support differentiated positioning without changing the active ingredient.

International licensing

Rights may be licensed by territory to companies with established osteoporosis sales forces or reimbursement infrastructure. Relevant markets include Europe, Japan, Canada, South Korea, Australia, and selected Latin American markets. The licensing value depends on local patent status, pricing controls, registration requirements, and the availability of generic teriparatide.

Manufacturing partnerships

A commercial partner with peptide synthesis, sterile fill-finish, cartridge assembly, and combination-product capabilities could reduce cost of goods. The key operational risks are peptide impurity control, preservative compatibility, aseptic processing, and device supply continuity.

What revenue exposure does BONSITY have?

BONSITY revenue is not generally disclosed as a standalone public line item. Radius Health’s reporting historically grouped BONSITY with other products or reported it without enough detail to isolate product-level sales. Commercial exposure is therefore best assessed through market share, net price, formulary access, prescription volume, and gross-to-net deductions rather than reported revenue alone.

The product’s revenue ceiling is constrained by:

• The two-year lifetime treatment limitation.
• Competition from FORTEO and other teriparatide products.
• Oral and injectable osteoporosis alternatives.
• Reimbursement restrictions.
• High specialty-pharmacy and patient-support costs.
• Generic-entry risk.
• Limited benefit from chronic refill persistence after treatment completion.

A differentiated formulation with longer storage, improved tolerability, or easier administration could increase net revenue per patient. An excipient-only change that does not alter handling, stability, or injection experience is unlikely to justify a substantial premium.

How can a competitor design around BONSITY?

A competing manufacturer can pursue several design-around paths:

1. Use a different buffer system, such as histidine or another pharmaceutically acceptable buffer.
2. Replace metacresol with another preservative or use a single-dose format.
3. Change the peptide concentration while maintaining the 20 mcg dose.
4. Use a disposable prefilled syringe rather than a multidose pen.
5. Modify the cartridge, dose-setting mechanism, or needle interface.
6. Seek approval for a formulation with a different in-use stability period.
7. Pursue a 505(b)(2) application based on comparative pharmacokinetics and clinical bridging.
8. File an ANDA with a formulation designed to meet applicable sameness requirements.

The highest-value design-around opportunity is a product that reduces cold-chain dependence or simplifies daily self-administration. Those changes can create real commercial differentiation while avoiding narrow formulation or device claims.

What FDA regulatory issues govern future BONSITY competitors?

Future products must address peptide identity, potency, purity, degradation products, aggregation, sterility, endotoxins, particulate matter, preservative effectiveness, container closure integrity, and device performance. FDA will also assess whether formulation differences affect pharmacokinetics, immunogenicity, injection-site tolerability, or clinical performance.

A 505(b)(2) applicant may have greater flexibility to use a different formulation or device, but the applicant must bridge the differences with appropriate analytical, pharmacokinetic, stability, usability, or clinical data. An ANDA applicant faces a more demanding sameness analysis but may gain a simpler commercial pathway if the product qualifies.

Key Takeaways

• BONSITY is a 505(b)(2) teriparatide injection approved in 2019.
• Its disclosed excipients are glacial acetic acid, sodium acetate trihydrate, mannitol, metacresol, and water for injection.
• The formulation supports acidic pH control, isotonicity, multidose preservation, and peptide stability.
• The excipients themselves are unlikely to create a broad commercial moat.
• Device integration, stability performance, manufacturing controls, and regulatory bridging are more important sources of competitive protection.
• BONSITY competes primarily with FORTEO and other teriparatide products in a limited-duration osteoporosis market.
• Generic and 505(b)(2) competition can emerge through Paragraph IV challenges, formulation design-arounds, or alternative delivery systems.
• Standalone BONSITY revenue is not generally disclosed, limiting direct revenue-exposure analysis.
• The strongest commercial opportunities are lower-cost access, payer contracting, adherence-focused devices, territorial licensing, and efficient peptide manufacturing.
• Current Orange Book listings, patent litigation, and settlement agreements must be reviewed before assigning a definitive loss-of-exclusivity date.

FAQs About BONSITY Excipient Strategy and Commercialization

Is BONSITY interchangeable with FORTEO?

BONSITY and FORTEO contain teriparatide, but pharmacy-level interchangeability depends on FDA-specific determinations and applicable state substitution laws. Therapeutic similarity does not automatically establish substitutability.

Does BONSITY contain metacresol?

Yes. Metacresol is used as an antimicrobial preservative in the multidose injectable formulation.

Can BONSITY be reformulated without metacresol?

Potentially, but a preservative-free presentation would likely require a single-dose container or another validated sterility-control strategy. The change could require substantial stability, sterility, device, and regulatory work.

Is there a biosimilar version of BONSITY?

No biosimilar designation applies to BONSITY because teriparatide products are regulated as peptide drug products under an NDA framework rather than as biosimilars under the abbreviated biologics pathway.

What is the most valuable next-generation BONSITY opportunity?

A product with improved room-temperature stability, simplified daily administration, lower injection force, or a lower net price has greater commercial potential than a formulation change limited to excipient substitution.

References

1. U.S. Food and Drug Administration. (2019a). BONSITY (teriparatide injection) approval letter, NDA 212553. FDA.

2. U.S. Food and Drug Administration. (2019b). BONSITY (teriparatide injection) prescribing information. FDA.

3. U.S. Food and Drug Administration. (n.d.-a). Approved drug products with therapeutic equivalence evaluations: Orange Book. FDA.

4. U.S. Food and Drug Administration. (n.d.-b). 505(b)(2) applications. FDA.

5. Radius Health, Inc. (2020). Annual report pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934. U.S. Securities and Exchange Commission.