concurring in the judgment.
I conclude that Hoeehst-Roussel is not entitled to extension of the term of the ’286 patent on the facts of this case, but my decision is based on different grounds from that of the panel majority. I can not agree that what is claimed and what is infringed must be interpreted differently for 35 U.S.C. § 156 than for any other provision of Title 35. In addition, the incorrect rulings concerning who is entitled to patent term extension should not be tacitly endorsed by the silence of the Federal Circuit.
I
The district court held that “a patent holder not attempting to market a product was not an intended beneficiary of § 156” and that Hoeehst-Roussel, not having itself sought regulatory market approval, could not apply for extension of the term of the ’286 patent. That holding is too broad, for § 156 is satisfied if the holder of the regulatory market approval acts as the agent of the patentee in applying for extension of the patent term; it is the holder of the market approval that is the primary intended beneficiary of § 156. In addition, it is incorrect to hold or imply that the applicant for market approval must have been the patentee or its agent at the time the approval was sought.
The purpose of the Patent Term Restoration Act is to strengthen the patent-based incentive to the commitment of financial resources to medicinal product development and marketing. Section 156 does not turn on whether the patent is owned by the entity that is marketing the product, or is merely licensed to that entity. However, neither is there an automatic right to term extension when the patentee does not itself participate in the FDA market approval process; all of the provisions of § 156 must be met. In the case at bar the statutory provisions were not met. On this ground, I concur in the judgment denying the extension.
A
Section 156 requires that the application for term extension be submitted by the patent owner “or its agent”:
(a) The term of a patent which claims a product, a method of using a product, or a method of manufacturing a product shall be extended in accordance with this section from the original expiration date of the patent if
(3) an application for extension is submitted by the owner of record of the patent or its agent and in accordance *762with the requirements of paragraphs (1) through (4) of subsection (d);
35 U.S.C. § 156(a)(3). When the patentee itself does not meet the requirements of § 156, the entity that is seeking regulatory market approval can act as the agent of the patentee for the purpose of applying for patent term extension. In this way the statute accommodates the situation of a patentee that does not itself market the product, but whose patent supports the commercial development and regulatory compliance activity.
Throughout § 156 is iterated the usage whereby the entity engaged in the regulatory review process is deemed the agent of the patentee in applying for the patent term extension. In that context the marketing entity provides the data concerning the development activities necessary to support the application for extension. For example, § 156(d)(1)(D) requires that the applicant for extension provide a description of its activities during the regulatory review period and the dates of such activities; this description may be provided by the marketing entity when the patentee has not itself engaged in such activities. Section § 156(c)(1) provides that the term of the extension is reduced by any period “during which the applicant for the patent extension did not act with due diligence during such period of the regulatory review period,” thus recognizing that the due diligence of the marketing entity, as applicant for extension, is what is relevant for purposes of calculating the term. Further, the provision for interim extensions, § 156(d)(5)(A), states that an application for interim extension may be filed if “the owner of record of the patent or its agent reasonably expects that the applicable regulatory review period ... may extend beyond the expiration of the patent term.” Again, the statute recognizes that the patent owner'may not have the information on which to base an expectation concerning the length of the regulatory review period, but that the participant in the regulatory review would have the reasonable expectation required by this provision, and would provide this information as agent of the patent owner.
Hoechst-Roussel argues that it is entitled to apply for and receive the patent term extension without participation of the holder of the marketing approval, citing the FDA regulation that “the actions of the marketing applicant shall be imputed to the applicant for patent term restoration.” 21 C.F.R. § 60.36(b). Hoechst-Roussel states that this imputed benefit removes the need for participation of the marketing entity. In its application for extension Hoechst-Roussel referred to Warner Lambert’s due diligence and regulatory approval activities “on information and belief,” as purported compliance with § 156(f)(1)(D) and (c)(1). Although FDA regulation § 60.36(b) implements the statutory provisions that accommodate a variety of relationships between patentee and marketing applicant, it does not override the requirement for compliance with all of the provisions of § 156. In this case the requirements were not met, for the participation of the marketing applicant as the agent of the patentee in securing the extension was necessary in order to describe pre-market activities, to establish diligence, and otherwise to comply with § 156.
Hoechst-Roussel raises several additional arguments for asserting entitlement to extension of the ’286 patent term despite the non-participation of the marketing applicant. Hoechst-Roussel states that since the ’286 patent was the first patent to issue with respect to Warner Lambert’s FDA-approved product, and Warner Lambert has not authorized any other patentee to rely on the regulatory approval that it obtained, the ’286 patent is the only patent that can be extended. Hoechst-Roussel cites 37 C.F.R. § 1.785(c)1 which provides:
(c) If an application for extension is filed which seeks the extension of the term of a patent based upon the same regulatory review period as that relied upon in one or more applications for extension pursuant to the requirements of this subpart, the certificate of extension of patent term will be issued on the application only if—
*763(3) The holder of the regulatory approval granted with respect to the regulatory review period is not an applicant and no applicant for extension holds an express and exclusive authorization from the holder of the regulatory approval to rely upon the regulatory review period as the basis for the application for extension and the application is for extension of the patent having the earliest date of issuance of those patents for which extension is sought based upon the same regulatory review period.
Although the parties discuss the potential extension of Dr. Summers’ later-issued patent, the status of that patent and the applicability of § 1.785(c) were not decided by the district court, and are not before us. In all events, § 1.785(c) does not authorize extension solely on the ground of being first; all of the statutory requirements must be met.
Hoechst-Roussel also refers to the lost income to a non-marketing patentee who can not sue the marketing applicant for infringement during the regulatory review period, citing 35 U.S.C. § 271(e) (overruling Roche Products, Inc. v. Bolar Pharmaceutical Co., 733 F.2d 858, 221 USPQ 937 (Fed.Cir.), cert. denied, 469 U.S. 856, 105 S.Ct. 183, 83 L.Ed.2d 117 (1984)). Section 271(e) permits premarket approval activity conducted for the sole purpose of sales after patent expiration. I discern no legislative intent specifically to benefit a non-marketing patentee on this ground.
Hoechst-Roussel also argues that support for research investment is part of the policy consideration for patent term extension. Although research expenditures are not irrelevant, the history of the extraordinary step of extending the patent term for pharmaceutical products shows that its target was the time consumed by and the high cost of development and regulatory approval. Although the initial discovery of a new medicinal product or use often derives from extensive and costly research, such research precedes filing the patent application and thus does not consume the patent’s life. Undoubtedly investment in research by commercial entities such as Hoechst-Roussel is motivated by the potential for economic benefit. However, the legislative history makes clear that the purpose of patent term restoration is to compensate for the years of development before commercial sale is authorized, and that the incentive to conduct the initial research is viewed in this broader context.
B
Thus the district court erred in denying Hoechst-Roussel’s application simply because Hoechst-Roussel was not marketing the product. To satisfy the statute when the patentee is not the holder of the market approval, the market approval entity acts as the agent of the patentee in applying for the extension and meeting the other statutory requirements such as due diligence. The litigation settlement license from Hoechst-Roussel to Warner Lambert did not eliminate the need for compliance with the statutory requirements. And while the PTO was on the right track when it required a relationship, such as a license, between the patent owner and the holder of the FDA approval, the PTO was incorrect in arguing that the relationship must have existed when the marketing efforts began.
Since HoechslARoussel did not meet the requirements of § 156, I would affirm the judgment denying the application for extension of the ’286 patent term.
II
Turning to the ground on which the panel majority decided the appeal, I do not share their view that even though the ’286 patent claims cover and would be infringed by use of the FDA-approved product, the requirements of 35 U.S.C. § 156 are not met. The approved product is converted into the claimed product in vivo; thus infringement occurs upon use of the approved product. There is no basis in the law for restricting § 156 to exclude this circumstance. The ’286 patent, which claims hydroxy-tacrine, is not barred from extension simply because the registered product, tacrine hydrochloride, forms hydroxy-tacrine only in vivo. The conversion to hydroxy-tacrine was established before the FDA, and infringement of the ’286 claims was conceded. The statutory *764requirements for this aspect of extension of the ’286 patent were met.
The panel majority states that “the concept of a ‘claim’ is different from the concept of infringement, and, as a result, the plain meaning of ‘claims’ is not the same as the plain meaning of infringement.” Majority op. at 6. The words are indeed different, and the distinctions are relevant in appropriate contexts.2 However, as applied to § 156, the legislative history makes quite clear that the term “claims” is used in the statute because it describes the protected subject matter of the patent:
The term “claims” was selected because it is the term used in the patent law to describe the invention which the patent owner or its assignee may prevent others from, making, using or selling during the seventeen year term of the patent____
H.R.Rep. No. 98-857, Part I at 37 (1984), reprinted in 1984 U.S.C.C.A.N. 2647, 2670 (emphasis added). The Report also states:
The policy which the Committee seeks to implement in paragraph (4)(A) is, in brief, that the first patent (1) which claims the approved product, in the sense that the approved product would infringe a claim of that patent ... is the patent which should be rewarded with an extension.
H.R.Rep. No. 98-857 at 38, reprinted in 1984 U.S.C.C.A.N. at 2671 (emphasis added). It is thus explained that the word “claims” was “selected” for the text of § 156 because the claims define what is infringed.
The purpose of § 156 is to extend the time during which the patent can be enforced against infringers, for a patent whose claims would be infringed by the FDA-approved product. Extending the period of enforcement against infringement is the way in which this legislation fulfills its purpose. The word “claim” is used in the statute for the purpose of implementing this purpose, not to provide a loophole when the claim would be directly infringed only upon use of the FDA-approved product. It is incorrect, and contrary to the purpose of the Patent Term Restoration Act, for this court now to create that loophole.
The panel majority states that the relationship between any claim and infringement is “tenuous.” Majority op. at 6. It is not tenuous; it is the core of the patent system. Section 156 does not require creation of a new, vague, and unnecessary distinction between what is claimed and what is infringed, unique to this section of Title 35. The FDA, the agency assigned responsibility for informing the PTO whether a particular product is covered by the patent for which extension is sought, so informed the PTO with respect to the ’286 patent and “Cognex.” It is not disputed that tacrine hydrochloride is converted in vivo to the hydroxy-tacrine of the ’286 claims. This metabolic path was established before the FDA. As explained in Zenith Labs., Inc. v. Bristol-Myers Squibb Co., 19 F.3d 1418, 1422, 30 USPQ2d 1285, 1288 (Fed.Cir.1994), in vivo conversion into the drug named in the claims is direct infringement. Since the registered product would directly infringe the claims during use, the product is covered by the claims and qualifies the claims for extension.
The distinction drawn by the panel majority leads to the curious result that the ’286 claims would be infringed for all purposes of Title 35 except for § 156. This result is not supported by the law of claiming, of infringement, or of term extension. Thus I must, respectfully, disagree with the panel majority’s decision on this ground.
. We are advised that the PTO has changed these regulations. Only the regulations in effect during the relevant period have been considered.
. For example, the distinction between what is claimed and what is infringed is manifest in the circumstance of infringement by equivalents, when a patent is infringed by something that is not claimed; and there may be infringement liability for inducement or contributory infringement. It is not before us to decide whether §156 authorizes extension of the term of a patent that is infringed under the doctrine of equivalents or as a matter of contributory or induced infringement, for the '286 claims are literally and directly infringed when tacrine hydrochloride is ingested.