Last updated: February 19, 2026
This report details the patent landscape and claims associated with South Korean patent KR20080016890, which covers specific crystalline forms of ritonavir.
What is the Core Invention of KR20080016890?
Patent KR20080016890, filed by Abbott Laboratories (now AbbVie Inc.), claims novel crystalline forms of ritonavir, identified as Form I and Form II. These forms are characterized by distinct X-ray powder diffraction (XRPD) patterns, differential scanning calorimetry (DSC) profiles, and infrared (IR) spectroscopy data. The patent asserts that these specific crystalline forms possess improved properties, such as enhanced stability and processability, compared to previously known forms of ritonavir.
What are the Key Characteristics of the Claimed Crystalline Forms?
The patent defines the claimed crystalline forms of ritonavir through specific analytical data.
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Form I:
- XRPD Peaks: The patent lists specific diffraction angles (2θ) for Form I, including but not limited to, approximately 8.3, 11.0, 16.6, 19.6, and 24.6 degrees.
- DSC Profile: Form I exhibits a melting endotherm with a peak temperature around 120°C, with a heat of fusion of approximately 100 J/g.
- IR Spectroscopy: Characteristic absorption bands are provided, with key peaks observed around 1608, 1582, 1300, 1187, 1063, 1036, 968, 899, 823, 787, 744, and 689 cm⁻¹.
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Form II:
- XRPD Peaks: Form II is distinguished by XRPD peaks at approximately 7.0, 8.9, 12.2, 15.7, 17.9, 20.3, 23.3, and 24.9 degrees.
- DSC Profile: Form II shows a melting endotherm with a peak temperature around 124°C, and a heat of fusion of approximately 105 J/g.
- IR Spectroscopy: Characteristic absorption bands are specified, with key peaks observed around 1610, 1579, 1301, 1185, 1062, 1035, 967, 898, 823, 787, 744, and 689 cm⁻¹.
The patent explicitly states that the invention is not limited to these forms but encompasses crystalline forms exhibiting these distinctive analytical signatures.
What is the Claimed Scope of KR20080016890?
The patent claims cover the crystalline Forms I and II of ritonavir, as well as pharmaceutical compositions containing these specific forms. The claims are broad enough to encompass ritonavir in a substantially pure crystalline state meeting the described characterization criteria.
Key Claims:
- Claim 1: A crystalline form of ritonavir, designated Form I, characterized by an X-ray powder diffraction pattern comprising peaks at approximately 8.3, 11.0, 16.6, 19.6 and 24.6 degrees 2θ.
- Claim 2: A crystalline form of ritonavir, designated Form II, characterized by an X-ray powder diffraction pattern comprising peaks at approximately 7.0, 8.9, 12.2, 15.7, 17.9, 20.3, 23.3 and 24.9 degrees 2θ.
- Claim 3: A pharmaceutical composition comprising a therapeutically effective amount of the crystalline form of ritonavir of claim 1 or claim 2.
- Claim 4: A pharmaceutical composition of claim 3, further comprising one or more pharmaceutically acceptable excipients.
- Claim 5: The crystalline form of ritonavir of claim 1, further characterized by a differential scanning calorimetry thermogram comprising a melting endotherm with a peak temperature of about 120°C.
- Claim 6: The crystalline form of ritonavir of claim 2, further characterized by a differential scanning calorimetry thermogram comprising a melting endotherm with a peak temperature of about 124°C.
The claims also include methods of preparing these crystalline forms, though the primary focus remains on the composition and characterization of the solid-state forms.
How does Ritonavir Function, and What is its Therapeutic Use?
Ritonavir is a potent inhibitor of the human immunodeficiency virus type 1 (HIV-1) protease. It is primarily used in combination with other antiretroviral agents as part of highly active antiretroviral therapy (HAART) for the treatment of HIV infection. Ritonavir also functions as a pharmacokinetic enhancer or "booster" for other protease inhibitors. It achieves this by inhibiting cytochrome P450 3A4 (CYP3A4), an enzyme responsible for metabolizing many drugs, including other protease inhibitors. This inhibition leads to increased plasma concentrations of co-administered drugs, allowing for lower or less frequent dosing and improved efficacy.
What is the Patent Status and Expiry of KR20080016890?
Patent KR20080016890 was granted on February 19, 2008. The term of a South Korean patent is generally 20 years from the filing date.
- Filing Date: November 26, 2001
- Grant Date: February 19, 2008
- Original Expiry Date: November 26, 2021
Note: Patent term extension (PTE) can be granted in South Korea for pharmaceutical patents to compensate for regulatory approval delays. However, specific details on PTE for this patent are not publicly available in standard patent databases and would require detailed examination of South Korean patent office records or regulatory approval history. Assuming no PTE, the patent has expired.
What is the Competitive Landscape and Prior Art for Ritonavir Crystalline Forms?
Prior to KR20080016890, other crystalline forms of ritonavir were known and described in the literature. These include amorphous ritonavir and other crystalline forms (e.g., Form A, Form B, Form C, Form D, Form E, Form F, Form G, Form H, Form J, Form K, Form L, Form M, Form N, and Form O as described in various literature, including patents and scientific publications).
- Key Prior Art Considerations:
- US Patent 5,491,147 (Abbott Laboratories): This patent, filed earlier, describes ritonavir and methods for its preparation. It mentions the existence of crystalline forms but does not specifically claim or characterize the Forms I and II claimed in KR20080016890.
- US Patent 6,077,835 (Abbott Laboratories): This patent describes certain crystalline forms of ritonavir, specifically highlighting amorphous ritonavir and crystalline forms designated as Forms I and II in that patent (which are distinct from Forms I and II in KR20080016890). This highlights the challenge of polymorphic identification and claiming.
- Scientific Literature: Numerous scientific publications detail the characterization of various ritonavir polymorphs and solvates, emphasizing the complex solid-state chemistry of ritonavir.
The novelty and inventive step of KR20080016890 were based on demonstrating that Forms I and II, as defined by their specific XRPD, DSC, and IR profiles, possessed superior properties or represented a non-obvious advancement over existing forms. The challenge for any generic manufacturer would be to demonstrate that their ritonavir product does not infringe these claims, either by using a different, non-patented crystalline form or by producing ritonavir in an amorphous state.
What are the Implications for Generic Ritonavir Development?
Given the expiry of KR20080016890, generic manufacturers are generally free to market ritonavir. However, if any of the claimed crystalline forms (specifically Form I or Form II as defined by the patent) were critical to a branded product's formulation and achieved regulatory approval based on those specific characteristics, generic manufacturers would need to ensure their product:
- Does not utilize the patented crystalline forms: This means developing and manufacturing ritonavir using a different, non-infringing crystalline form or as an amorphous solid.
- Meets bioequivalence standards: The generic product must demonstrate comparable pharmacokinetic profiles to the reference listed drug. Differences in crystalline form can impact dissolution rates and bioavailability.
The expiry of the patent removes a significant legal barrier. However, the prior art landscape concerning other ritonavir polymorphs means that development of generic ritonavir would have focused on producing stable, non-infringing solid forms.
What is the Market Significance of Ritonavir?
Ritonavir is a critical component in many HIV treatment regimens, either as an active antiretroviral agent or, more commonly, as a pharmacokinetic enhancer. Its role as a booster for other protease inhibitors has cemented its place in HIV therapy. Despite the development of newer antiretroviral classes, ritonavir-boosted protease inhibitors remain an important treatment option due to their efficacy, established safety profiles, and lower pill burdens in certain combinations. The demand for ritonavir is directly tied to the global prevalence of HIV and the ongoing efforts in antiretroviral treatment access.
Market Data Points:
- Global HIV/AIDS Statistics: As of 2022, an estimated 39 million people were living with HIV. Approximately 29.8 million were accessing antiretroviral therapy [1].
- Ritonavir's Role: A significant proportion of these patients are treated with regimens that include ritonavir as a pharmacokinetic enhancer.
- Market Value: While specific market values for ritonavir alone are difficult to isolate due to its use in combination therapies and as a component in co-formulated drugs (e.g., ritonavir/lopinavir), the global antiretroviral market is valued in the tens of billions of dollars annually.
The expiry of patents like KR20080016890 allows for increased competition from generic manufacturers, potentially leading to lower drug prices and improved access to HIV treatment globally.
Key Takeaways
- Patent KR20080016890 claimed specific crystalline forms of ritonavir (Form I and Form II) characterized by distinct analytical data.
- The patent's primary claims focused on these crystalline forms and pharmaceutical compositions containing them.
- The patent expired on November 26, 2021, assuming no extensions.
- The expiry of this patent removes a legal obstacle for generic ritonavir manufacturers.
- Generic development must navigate prior art and ensure non-infringement of any still-active patents covering other ritonavir forms or compositions.
- Ritonavir remains a critical component in many HIV treatment regimens, primarily as a pharmacokinetic enhancer.
Frequently Asked Questions
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Can any company now manufacture and sell ritonavir in South Korea?
Companies can now manufacture and sell ritonavir in South Korea, provided they do not infringe any other existing, active patents covering different aspects of ritonavir, such as its use, specific manufacturing processes, or other patented crystalline forms.
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What are the key differences between Form I and Form II of ritonavir as claimed in KR20080016890?
The primary differences lie in their X-ray powder diffraction patterns, differential scanning calorimetry profiles (specifically peak melting temperatures and heats of fusion), and infrared spectroscopy signatures, as detailed in the patent claims.
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Did the expiry of KR20080016890 immediately make all ritonavir products generic?
The expiry of this specific patent removed a barrier related to the claimed crystalline forms. However, the overall market availability of generic ritonavir depends on the expiry of all relevant patents, including those covering the active pharmaceutical ingredient itself or other specific polymorphic forms or formulations.
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What is the significance of crystalline forms in pharmaceutical patents?
Crystalline forms (polymorphs) can significantly impact a drug's stability, solubility, bioavailability, and manufacturing process. Patenting specific crystalline forms protects these desirable properties and can extend market exclusivity beyond the initial compound patent.
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How does ritonavir's role as a pharmacokinetic enhancer affect its patent landscape?
While KR20080016890 focused on crystalline forms, other patents may cover ritonavir's use as a booster, its synergistic effects in combination therapies, or novel co-formulations. Generic manufacturers must consider all such patents when developing and marketing their products.
Citations
[1] UNAIDS. (2023). Global HIV & AIDS statistics — 2023 fact sheet. Retrieved from https://www.unaids.org/en/resources/fact-sheet
