Types of ANDA Filing in the US: Para I, II, III, IV Explained with Examples
By PharmaShare Regulatory Team | US FDA Regulatory Affairs | August 2026
1. What is ANDA?
ANDA = Abbreviated New Drug Application – Filed under Section 505(j) of FD&C Act to get approval for a generic version of an already approved branded drug (RLD – Reference Listed Drug).
Word “Abbreviated” because you don’t need to do clinical trials again. You only need to prove Bioequivalence (BE) + Pharmaceutical Equivalence.
Regulated by Office of Generic Drugs (OGD) under CDER, USFDA.
Key Requirement: Your drug must be same as RLD in – Active Ingredient, Dosage Form, Strength, Route, Labeling (with some exceptions), and BE.
2. The Orange Book & Patents – Base for ANDA Types
Before filing ANDA, you must check FDA Orange Book for the RLD. Orange Book lists:
- Patents covering the drug (Drug Substance, Drug Product, Method of Use)
- Exclusivity (NCE, Orphan, Pediatric etc.)
When you file ANDA, you must make a Certification against EACH patent listed in Orange Book. This certification decides your ANDA type.
This is called Paragraph I, II, III, IV Certification – 21 CFR 314.94(a)(12).
3. Types of ANDA Filing – Detailed Breakdown
| Type | Meaning | When to Use | Approval Impact |
|---|---|---|---|
| Para I | Patent information has NOT been filed in Orange Book | No patent listed for RLD | Can be approved immediately after ANDA review |
| Para II | Patent has ALREADY EXPIRED | Patent expired before your filing | Can be approved immediately |
| Para III | Patent will expire on a specific date, will NOT market before that | You accept patent and wait for expiry | FDA will give Tentative Approval till patent expires, then Final Approval |
| Para IV | Patent is INVALID, UNENFORCEABLE, or will NOT be infringed by your product | You CHALLENGE the brand patent | Most lucrative. If you are First-to-File, you get 180-Day Exclusivity. Triggers 45-day litigation window |
4. Para IV in Detail – The Money Maker
Para IV is the most important filing strategy for any generic companies.
Process Flow:
Step 2: Notify RLD NDA Holder & Patent Owner within 20 days of FDA acceptance (Para IV Notice Letter)
Step 3: Brand has 45 days to sue you for patent infringement
Step 4: If brand sues within 45 days → 30-Month Stay – FDA cannot give Final Approval for 30 months or till court decision (whichever earlier)
Step 5: If you win case or patent invalid → FDA gives Final Approval → You launch as First Generic with 180 days exclusivity (huge profit)
Step 6: If brand does NOT sue in 45 days → No 30-month stay, FDA can approve anytime
5. Other Types of ANDA-related Filings You Must Know
| Filing Type | Purpose |
|---|---|
| Section viii Statement | Not exactly ANDA type, but alternative to Para IV. You carve out the patented method-of-use from your label. You say – “We are not seeking approval for that patented use”. No need to notify brand. No 45-day litigation. |
| Petitioned ANDA (Suitability Petition) | When you want a change vs RLD – e.g., different strength, dosage form, route. You need prior approval of petition (505(j)(2)(C)). Example: RLD is 100mg tablet, you want 50mg. After petition approved, you file ANDA as Para I/II/III/IV. |
| No Patent Listing / NDA Not Listed | Sometimes RLD discontinued and no patent info. You file as Para I automatically. |
6. How to Choose Which Para to File? – Decision Tree
Check Orange Book →
➡️ No patent listed? → File Para I
➡️ Patent listed but expired? → File Para II
➡️ Patent active & you want to wait? → File Para III (Mention expiry date – You get Tentative Approval)
➡️ Patent active but you believe it is weak / you have design-around? → File Para IV + Section viii if applicable (High Risk, High Reward)
Note: If multiple patents listed, you need separate certification for EACH patent. Example: 1 patent expired (Para II) + 1 active you challenge (Para IV) = Your ANDA is considered Para IV filing overall.
7. ANDA Filing Checklist in 2026
- Identify RLD in Orange Book – Check TE Code (AB rated is needed)
- Download Patent & Exclusivity info
- Decide Para Certification strategy with IP & Legal
- Conduct BE Study at USFDA approved CRO (Fasting + Fed if needed)
- Prepare Module 1 to 5 in eCTD format
- Include Para I-IV + Section viii statement with detailed justification
- Pay GDUFA Fee – In FY 2026 ~ $240,000 per ANDA
- Submit to OGD – Get acknowledgement + Filing Date
- If Para IV – Send Notice Letter within 20 days (very critical deadline)
Conclusion
Para I & II = Easy approval, but no exclusivity, more competition.
Para III = Safe play, wait for patent to expire.
Para IV = Aggressive play, you challenge patent, you can become First Generic and earn 180-day exclusivity worth $50-500M depending on product.
That’s why every generic company has a dedicated team for Patent & Para IV assessment before they even start formulation.
Pro Tip for QA/RA: Always review Orange Book on the day of filing. Patents get listed daily. If new patent lists after your filing but before approval, FDA will ask you to certify again.
⚠️ Regulatory & Legal Disclaimer
Informational Purpose Only: This article is for educational purposes only and does not constitute legal, regulatory, or business advice. ANDA filing requirements are governed by Federal Food, Drug, and Cosmetic Act, 21 CFR Part 314, and FDA guidance documents which change frequently.
No Affiliation: PharmaShare is not affiliated with USFDA, OGD, CDER, or any law firm. Information is based on publicly available FDA guidance as of August 2026. Readers must refer to official FDA website and consult a qualified US regulatory attorney before making Para I-IV decisions.
No Liability: PharmaShare does not guarantee approval, exclusivity, or outcome of any ANDA filing. Patent challenges involve significant legal risk. Always conduct independent IP assessment.
About the Author
Mahummed Asif is a experienced pharmaceutical QA professional and publisher of Pharmashare. He has sound knowledge in GMP, Product Life Cycle Management, Regulatory filing, QMS, Product Complaint Management, Change control, risk management, and global audit preparation.