DETAILED ACTION
Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Priority
This application is a 371 of PCT/IN2020/050775 which claims the benefit of IN 201911035946 with an effective filing date of 06 September 2019 as reflected in the filing receipt mailed on 25 May 2022.
Status of the Claims
Claims 1-4 and 7 are pending.
Claim 2 is currently amended.
Claims 5 and 6 were previously cancelled.
Response to Amendments
Applicant’s amendments filed 29 January 2026 are acknowledged.
Claim Rejections - 35 USC § 112
Applicant’s amendment to claim 2 is sufficient to overcome the rejection of claim 2 under 35 U.S.C. 112(b) as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor regards as the invention. Claim 2 has been amended to define the equivalent ratio as a molar ratio. The rejection is withdrawn.
Response to Arguments
Applicant’s arguments filed 29 January 2026 have been fully considered but they are not persuasive.
Applicant’s argue that Hong, Correia, Kessler Chemical Inc., and PubChem do not disclose the limitations as recited in claim 1. These arguments have been considered but are not persuasive for the reasons set forth in the maintained grounds of rejection below and the response to arguments below.
In response to applicant’s arguments on pages 4-6 of the remarks filed on 29 January 2026 that it would have not been obvious to a person of ordinary skill in the art to modify the horizontal screw reactor of Hong with the vertical screw reactor of Correia because “Hong does not disclose or suggest the use of a vertical screw reactor” and “Correia does not employ a vertical twin-screw conveyor as a reactor for the synthesis of metformin”. The test for obviousness is not whether the features of a secondary reference may be bodily incorporated into the structure of the primary reference; nor is it that the claimed invention must be expressly suggested in any one or all of the references. Rather, the test is what the combined teachings of the references would have suggested to those of ordinary skill in the art, see In re Keller, 642 F.2d 413, 208 USPQ 871 (CCPA 1981) and MPEP 2145.
An “obvious to try” rationale may support a conclusion that a claim would have been obvious where one skilled in the art is choosing from a finite number of identified, predictable solutions, with a reasonable expectation of success, see MPEP 2145 X.B.
Hong teaches in Example 5 “[t]he difference from Example 1 is that the reaction device 20 is an intermittent reactor, the discharge port of the reactor is connected to the inlet of the screw extruder, the screw extruder contains mutually meshing screws, and the axial direction of the screw is perpendicular to the axial direction of the intermittent reactor, and the synthesis reaction time is 2h”, see Paras. [0063]-[0066];[0077]; Fig. 1. Therefore, Hong does suggest the use of a perpendicular/vertical screw reactor.
Correia teaches “any known continuous reactor that is suitable for handling melts can be used in the process according to the invention. Appropriate continuous reactors that can be used for the execution of the process comprises continuous stirred tank reactors, single or twin-screw extruders, single or twin-screw kneaders or combinations of continuous stirred tank reactors, single or twin-screw extruders and single or twin-screw kneaders. Hence the present invention is directed as well to the process that is characterized in that the continuous reactor is a continuous stirred tank reactor, a single or twin-screw extruder, a single or twin-screw kneader or a combination of continuous stirred tank reactors, single or twin-screw extruders and single or twin-screw kneaders”, see Pg. 7, Ln. 22-Pg. 8, Ln. 2, where Example 2 specifically employs “a vertical twin- screw conveyor” in a continuous process, see Pg. 11, Lns. 19-30.
Since both Hong and Correia teach vertical/perpendicular screw conveyors and reactors for use in a metformin hydrochloride synthesis system, the prior art contains “detailed enabling methodology, a suggestion to modify the prior art to produce the claimed invention, and evidence suggesting the modification would be successful”, see MPEP 2145 X.B.; therefore, it would have been obvious for one of ordinary skill in the art at the time the invention was made to try combinations of the screw reactors/conveyors taught by Hong and Correia, such as a vertical screw reactor, for use in a metformin hydrochloride synthesis system.
For the reasons indicated above, applicant’s above arguments are not persuasive.
In response to applicant’s arguments on pages 5-6 of the remarks filed on 29 January 2026 that there are “two significant advantages associated with the use of a vertical screw reactor” one is the reduction in “unwanted liquid retention” and the other is the ability to allow “gases to rise vertically and escape from the top of the reactor”.
It is noted that instant claim 1 does not recite limitations drawn to liquid retention or the escape of gases.
The fact that the inventor has recognized another advantage which would flow naturally from following the suggestion of the prior art cannot be the basis for patentability when the differences would otherwise be obvious, see Ex parte Obiaya, 227 USPQ 58, 60 (Bd. Pat. App. & Inter. 1985). In addition, “[t]o establish unexpected results over a claimed range, [appellants] should compare a sufficient number of tests both inside and outside the claimed range to show the criticality of the claimed range.” In re Hill, 284 F.2d 955, 128 USPQ 197 (CCPA 1960), see MPEP 716.02(d).
Instant application claim 1 recites “a vertical screw reactor”. Applicant’s argue, as stated above, there are “two significant advantages associated with the use of a vertical screw reactor” one is the reduction in “unwanted liquid retention” and the other is the ability to allow “gases to rise vertically and escape from the top of the reactor”; however, Applicants have not provided a proper comparison to the closest prior art and have not established test points inside and outside the claimed range of the use of a vertical screw reactor as compared to a horizontal screw reactor in order to support their argument of surprising and unexpected results, see MPEP 716.02(e).
Applicant’s state on page 5 of the remarks “the horizontal reactor employed by Hong, can lead to liquid retention within the reactor interior”; however, as stated above, Paras. [0063]-[0066];[0077]; and Fig. 1 of Hong suggest the use of a perpendicular/vertical screw reactor that will inherently also lead to a reduction in “unwanted liquid retention” and allow “gases to rise vertically and escape from the top of the reactor”, see MPEP 2112.
The instant specification cannot be relied upon for any comparison tests/examples because the instant specification does not perform any comparisons or tests in a horizontal screw reactor. Therefore, the instant specification does not provide a comparison to the closest prior art and tests outside the use of a vertical screw reactor, such as by the use of a horizontal screw reactor, in order to support the argument of surprising and unexpected results relating to the metformin hydrochloride synthesis system, see MPEP 716.02(e).
For the reasons indicated above, applicant’s above arguments are not persuasive.
Maintained Rejections based on the Reply and Amendments to the claims filed on 29 January 2026
Claim Interpretation
The “single step” process limitation in instant application claim 1 is interpreted as a single step device with separate inputs, separate outputs, mixing feed funnels, etc. included in the single step, as depicted in instant specification FIG. 1 and Para. [0032]. In addition, cooling of a heated reaction product in order for it to be handled, collected, and used as intended is an inherent process step after hot melt extrusion, see MPEP 2112, and the instant specification incorporates an inherent cooling step, see instant specification Para. [0059] stating “it crystallizes on its own at 25-30° C. during collection”. Therefore, cooling is also interpreted as within the scope of the “single step” in instant application claim 1.
Claim Rejections - 35 USC § 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows:
1. Determining the scope and contents of the prior art.
2. Ascertaining the differences between the prior art and the claims at issue.
3. Resolving the level of ordinary skill in the pertinent art.
4. Considering objective evidence present in the application indicating obviousness or nonobviousness.
This application currently names joint inventors. In considering patentability of the claims the examiner presumes that the subject matter of the various claims was commonly owned as of the effective filing date of the claimed invention(s) absent any evidence to the contrary. Applicant is advised of the obligation under 37 CFR 1.56 to point out the inventor and effective filing dates of each claim that was not commonly owned as of the effective filing date of the later invention in order for the examiner to consider the applicability of 35 U.S.C. 102(b)(2)(C) for any potential 35 U.S.C. 102(a)(2) prior art against the later invention.
Claims 1-4 stand rejected under 35 U.S.C. 103 as being unpatentable over Hong et al. (CN108178738, published 19 June 2018, hereinafter Hong, see machine translation) in view of Correia et al. (WO2019154769, hereinafter Correia).
Hong teaches the claims 1 and 4 limitations of a metformin hydrochloride synthesis system having a single step reaction device, the reaction device 20 is provided with a feeding port and a reaction material discharge port, and is used for synthesizing metformin hydrochloride by a melting method, wherein a screw unloading part is arranged inside the reaction device to discharge metformin hydrochloride from the reaction material discharge port discharge and the reaction raw materials are added from the feeding port, and the screw discharge part can discharge the reaction product from the reaction material discharge port through screw extrusion, thus solving the problem that the solid material has a large stirring resistance and cannot be stirred, see Abstract and Claims 1-4, 8, 12 and 13. The reaction device is a hot melt extrusion device, see Para. [0022], that performs a continuous synthesis reaction of metformin hydrochloride by subjecting the reaction raw materials to a melting reaction and cooling in sequence to obtain metformin hydrochloride, i.e., cooling is an inherent process step after hot melt extrusion, see MPEP 2112 and Para. [0025], meeting the single step continuous process for the synthesis in instant application claim 1;
Specifically, solid dicyandiamide aka 2-cyanoguanidine and solid dimethylamine hydrochloride were added into the device, the reaction materials are transformed into a molten state by passing through a heating section and are pushed forward by a spiral discharge component of intermeshing screws to undergo a melting reaction for a time of about 8 minutes aka 480 seconds to 100 minutes and a temperature of 130-190 ◦C, preferably 150-170 ◦C, to obtain a yield of solid metformin hydrochloride of 93.02 wt% and a purity of 97.53 wt% see Paras. [0044];[0055]-[0060];[0063]-[0066], meeting:
The reactants, within the limited temperature range, within the limited time range, the screw reactor, within the purity range, and free of solvent and additives in instant application claim 1; and,
The reactant solid form in instant application claim 4.
Hong does not teach:
The instant application claim 1 limitations of reacting in a vertical screw reactor to obtain crystalline metformin hydrochloride; and,
The limitations in instant application claims 2 and 3.
Hong teaches the reactor is a screw reactor, see Paras. [0017];[0040], the molar ratio of the dicyandiamide and dimethylamine hydrochloride is 1:1.2, see Para. [0064], the raw materials react further following the process, and a high conversion of the raw materials, see Para. [0060].
Correia teaches a continuous process for the synthesis of metformin hydrochloride without a solvent in a vertical twin-screw conveyor prepared by the melt extrusion of dimethylammonium chloride aka dimethylamine hydrochloride and dicyanodiamide aka 2-cyanoguanidine at a molar ratio of from 1.0 to 2.0:1, see Pg. 1, Ln. 21-Pg. 2, Ln. 2; Pg. 2, Ln. 25-Pg. 3, Ln. 12; Pg. 7, Ln. 13-Pg. 8, Ln. 23, meeting:
The vertical screw reactor in instant application claim 1;
Within the equivalent ratio in instant application claim 2;
The reaction with 0% added water and 0% added metformin HCl contains only grams dimethylammonium chloride and grams dicyanodiamide, where the reaction is maintained until the reactants are completely converted, i.e., a 100% conversion of the reactants to create metformin HCl of varying purity leads to 100% selectivity towards metformin hydrochloride, to obtain crystalline metformin HCl of high purity, see Pg. 2, Ln. 25-Pg. 3, Ln. 12; Pg. 8, Ln. 24-Pg. 9, Ln. 1; Pg. 11, Lns. 1-30, meeting:
The crystalline metformin hydrochloride in instant application claim 1; and,
Within the range of selectivity towards metformin hydrochloride in instant
application claim 3.
In reference to the above claims, it would have been obvious to one of ordinary
skill in the art, before the effective filing date of the claimed invention, to have modified Hong to adjust the molar ratio, to use a vertical screw reactor, increase the conversion/selectivity, and to cool the metformin HCl in order to allow it to crystallize, see MPEP 2144.05 II., 2144.04 IV.B. and as taught by Correia, with a reasonable predictability of success for the purpose of efficiently producing metformin HCl of high purity without the use of solvents in order to reduce synthesis time and cost, see Correia, Pg. 2, Lns. 11-24.
The rationale to support a conclusion that the claim would have been obvious is that “a person of ordinary skill has good reason to pursue the known options within his or her technical grasp. If this leads to the anticipated success, it is likely that product [was] not of innovation but of ordinary skill and common sense”, see MPEP 2143 I.E. Since both Hong and Correia teach the solvent free production of metformin HCl by melt screw extrusion of dicyandiamide aka 2-cyanoguanidine and dimethylamine hydrochloride, a person of ordinary skill in the art has good reason to produce metformin HCl by pursuing the known options within their technical grasp for the benefit of efficiently producing metformin HCl of high purity without the use of solvents in order to reduce synthesis time and cost, see Correia, Pg. 2, Lns. 11-24 and MPEP 2141.
As stated in Sakraida v. Ag Pro, Inc., 425 U.S. 273, 189 USPQ 449, reh’g denied,
426 U.S. 955 (1976), “[w]hen a work is available in one field of endeavor, design
incentives and other market forces can prompt variations of it, either in the same field
or a different one. If a person of ordinary skill can implement a predictable variation, §
103 likely bars its patentability. For the same reason, if a technique has been used to
improve one device, and a person of ordinary skill in the art would recognize that it
would improve similar devices in the same way, using the technique is obvious unless its
actual application is beyond his or her skill”, see MPEP 2141.
Changes in configuration or shape, such as a vertical screw extruder, is a matter of choice which a person of ordinary skill in the art would have found obvious, such as applying the assistance of gravity in the extrusion, absent persuasive evidence that the particular configuration as claimed was significant, see MPEP 2144.04 IV.B.
In addition, “[i]t is a settled principle of law that a mere carrying forward of an original patented conception involving only change of form, proportions,” such as reactant concentrations and extruder shape, “or degree, or the substitution of equivalents doing the same thing as the original invention, by substantially the same means,” such as allowing the product to cool to room temperature and inherently crystallize, “is not such an invention as will sustain a patent, even though the changes of the kind may produce better results than prior inventions. In re Williams, 36 F.2d 436, 438, 4 USPQ 237 (CCPA 1929)”, see MPEP 2144.05.
Claim 7 stands rejected under 35 U.S.C. 103 as being unpatentable over Hong et al. (CN 108178738, published 19 June 2018, hereinafter Hong, see machine translation) in view of Correia et al. (WO2019154769, hereinafter Correia), as applied to claims 1-4 in the 35 USC 103 rejection above, in further view of Kessler Chemical Inc. (“Dimethylamine Hydrochloride”, 2017, Technical Data Sheet, Pgs. 1-2, hereinafter Kessler) and PubChem, (“Dicyandiamide”, 18 September 2015, Compound Summary for CID 10005, Pgs. 1-27).
Hong does not specifically teach the limitations in instant application claim 7.
Hong teaches solid dicyandiamide aka 2-cyanoguanidine and solid dimethylamine hydrochloride were added into the device, see Paras. [0044];[0055].
Kessler teaches dimethyl amine hydrochloride is a white crystalline powder, see Pg. 1, meeting the powdered dimethyl amine hydrochloride in instant application claim 7.
PubChem teaches dicyandiamide aka 2-cyanoguanidine is a dry powder, see Pg. 7, 4.2.1, meeting the powdered dicyandiamide in instant application 7.
In reference to the above claims, it would have been obvious to one of ordinary
skill in the art, before the effective filing date of the claimed invention, to have modified the solids of Hong to use free flowing powdery solids of the reactants, as taught by Kessler and PubChem with a reasonable predictability of success for the purpose of using a pharmaceutical form of the reactants other than pellets or large crystals with a higher surface area in order to allow thorough mixing and heat exchange in the reaction, see PubChem, Pg. 7, 4.2.1; Pg, 20, 10.2.2. and Kessler, Pg. 2.
The rationale to support a conclusion that the claim would have been obvious is that “a person of ordinary skill has good reason to pursue the known options within his or her technical grasp. If this leads to the anticipated success, it is likely that product [was] not of innovation but of ordinary skill and common sense”, see MPEP 2143 I.E. Since Hong teaches the reactants are in solid form and Kessler and PubChem teach the solid form of the reactants as powders, a person of ordinary skill in the art has good reason to produce metformin HCl by pursuing the known options within their technical grasp for the benefit of efficiently producing metformin HCl by using a pharmaceutical form of the reactants other than pellets or large crystals with a higher surface area in order to allow thorough mixing and heat exchange in the reaction, see PubChem, Pg. 7, 4.2.1; Pg, 20, 10.2.2, and Kessler, Pg. 2, and MPEP 2141.
As stated in Sakraida v. Ag Pro, Inc., 425 U.S. 273, 189 USPQ 449, reh’g denied,
426 U.S. 955 (1976), “[w]hen a work is available in one field of endeavor, design
incentives and other market forces can prompt variations of it, either in the same field
or a different one. If a person of ordinary skill can implement a predictable variation, §
103 likely bars its patentability. For the same reason, if a technique has been used to
improve one device, and a person of ordinary skill in the art would recognize that it
would improve similar devices in the same way, using the technique is obvious unless its
actual application is beyond his or her skill”, see MPEP 2141.
Selection of a known material, such as powder free flowing solid forms, based on its suitability for its intended use supported a prima facie obviousness determination in Sinclair & Carroll Co. v. Interchemical Corp., 325 U.S. 327, 65 USPQ 297 (1945), see MPEP 2144.07.
In addition, “[i]t is a settled principle of law that a mere carrying forward of an original patented conception involving only change of form,” such as powdery free forms, “proportions, or degree, or the substitution of equivalents doing the same thing as the original invention, by substantially the same means, is not such an invention as will sustain a patent, even though the changes of the kind may produce better results than prior inventions. In re Williams, 36 F.2d 436, 438, 4 USPQ 237 (CCPA 1929)”, see MPEP 2144.05.
Conclusion
No claims are allowed.
THIS ACTION IS MADE FINAL. Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a).
A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action.
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/YO/Examiner, Art Unit 1692
/FEREYDOUN G SAJJADI/Supervisory Patent Examiner, Art Unit 1699
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