Patents by Inventor Rama K. Haldar
Rama K. Haldar has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
-
Patent number: 5294644Abstract: The invention relates to properties and uses of N-hydrocarbon substituted lactams, particularly N-alkyl substituted lactams having the formula ##STR1## wherein R' is a hydrophobic radical such as linear or branched chain alkyl group containing from 8 to 27 carbon atoms, most preferably micelle forming pyrrolidones having 12 to 16 carbon atoms in the R' group. The invention particularly relates to the uses of the N-hydrocarbon substituted lactams which involve surfactant properties, such as solubility, wetting, viscosity building, emulsifying and/or complexing properties.Type: GrantFiled: February 12, 1991Date of Patent: March 15, 1994Assignee: ISP Investments Inc.Inventors: Robert B. Login, Ratan K. Chaudhuri, Rama K. Haldar, Mohamed M. Hashem, Michael W. Helioff, David J. Tracy
-
Patent number: 5262171Abstract: A pharmaceutical tablet is provided herein having an effective dissolution rate. The tablet contains a pharmaceutically-active ingredient and a substantially linear, i.e. non-crosslinked K-30 to K-120 PVP as a binding agent. The PVP used herein is made by an initiated polymerization process in which vinyl pyrrolidone monomer is polymerized in the presence of an initiator which produces a linear PVP polymerization, i.e. is a poor hydrogen abstractor of PVP polymer backbones, which would produce a disadvantageous crosslinked PVP product. Suitable initiators include low energy peroxyester free radical initiators, such as t-amylperoxy pivalate, an azo initiator, or a redox initiator which can perform at low temperatures.Preferably the residual initiator level in the PVP is reduced to less than 500 ppm, thereby further precluding the possibility of crosslinking of the PVP polymer during the shelf-life of the tablet.Type: GrantFiled: November 25, 1991Date of Patent: November 16, 1993Assignee: ISP Investments Inc.Inventors: Robert B. Login, Mohammed Tazi, Jui-Chang Chuang, Rama K. Haldar, Dinesh Jaiswal, Chi-San Wu
-
Controlled release tablets including strongly swellable, moderately crosslinked polyvinylpyrrolidone
Patent number: 5252611Abstract: What is described herein is a controlled release, drug-delivery composition which comprises a strongly swellable, moderately crosslinked polyvinylpyrrolidone polymer in the form of fine white powders having a defined aqueous gel volume and Brookfield viscosity which is prepared by precipitation polymerization in the presence of a prescribed amount of crosslinking agent, and an effective amount of a pharmaceutical medicament.Type: GrantFiled: July 20, 1992Date of Patent: October 12, 1993Assignee: ISP Investments Inc.Inventors: Jenn S. Shih, Jui-Chang Chuang, Rama K. Haldar -
Patent number: 5147941Abstract: According to this invention, there is provided a denture adhesive which is a mixed partial salt of a copolymer of maleic anhydride and acrylic acid (or methacrylic acid), optionally including a C.sub.1 -C.sub.4 alkyl vinyl ether, having a weight average molecular weight of about 30,000 to 400,000, preferably about 50,000 to 350,000. The copolymer comprises about 10 to 70 mole percent, preferably 20 to 60 mole percent, of maleic anhydride, about 30 to 90 mole percent, preferably 40 to 80 percent, of acrylic acid (or methacrylic acid), and 0 to 25 mole percent of a C.sub.1 -C.sub.4 alkyl vinyl ether.Type: GrantFiled: November 1, 1991Date of Patent: September 15, 1992Assignee: ISP Investments Inc.Inventors: Mohammed Tazi, Robert B. Login, Krystyna Plochocka, Rama K. Haldar, Balgopal Gangadharan, William E. Prosise
-
Patent number: 5093031Abstract: The invention relates to properties and uses of N-hydrocarbon substituted lactams, particularly N-alkyl substituted lactams having the formula ##STR1## wherein R' is a hydrophobic radical such as linear or branched chain alkyl group containing from 8 to 27 carbon atoms, most preferably micelle forming pyrrolidones having 12 to 16 carbon atoms in the R' group. The invention particularly relates to the uses of the N-hydrocarbon substituted lactams which involve surfactant properties, such as solubility, wetting, viscosity building, emulsifying and/or complexing properties.Type: GrantFiled: October 14, 1988Date of Patent: March 3, 1992Assignee: ISP Investments Inc.Inventors: Robert B. Login, Ratan K. Chaudhuri, Rama K. Haldar, Mohamed M. Hashem, Michael W. Helioff, David J. Tracy
-
Patent number: 5066709Abstract: This invention relates to superior bioadhesive compositions having time extended adhesive properties comprising a non-toxic carrier and a polymer having between about 45 and about 70 weight % of units having the structure ##STR1## between about 50 and about 30 weight % of units having the structure ##STR2## and 2 to 7 weight % of an amine salt containing a lactam functionally derived from A and/or B, wherein R is hydrogen, alkoxy, phenyl, carboxy or --N lactam having from 3 to 6 carbon atoms; R.sub.1 is C.sub.1 to C.sub.6 alkylene and R.sub.2 is C.sub.2 to C.sub.4 alkylene; said copolymer having a number average molecular weight of about 40,000 to about 500,000 and a relatively small particle size. The invention also relates to the method of synthesizing and using the above composition.Type: GrantFiled: September 20, 1990Date of Patent: November 19, 1991Assignee: GAF Chemicals CorporationInventors: Ratan K. Chaudhuri, Rama K. Haldar, Balgopal Gangadharan
-
Patent number: 5055046Abstract: This invention relates to superior bioadhesive compositions having time extended adhesive properties comprising a non-toxic carrier and a polymer having between about 45 and about 70 weight % of units having the structure ##STR1## between about 50 and about 30 weight % of units having the structure ##STR2## and 2 and 7 weight % of an amine salt containing a lactam functionality derived from A and/or B, wherein R is hydrogen, alkoxy, phenyl, carboxyl or --N lactam having from 3 to 6 carbon atoms; R.sub.1 is C.sub.1 to C.sub.6 alkylene and R.sub.2 is C.sub.2 to C.sub.4 alkylene; said copolymer having a number average molecular weight of about 40,000 to about 500,000 and a relatively small particle size. The invention also relates to the method of synthesizing and using the above composition.Type: GrantFiled: April 8, 1991Date of Patent: October 8, 1991Assignee: ISP Investments Inc.Inventors: Ratan K. Chaudhuri, Rama K. Haldar, Balgopal Gangadharan
-
Patent number: 5037924Abstract: According to this invention, there is provided a denture adhesive which is a mixed partial salt of a terpolymer of maleic anhydride, (MA) a C.sub.1 -C.sub.4 alkyl vinyl ether (AVE) and isobutylene (IB) vinyl ether, having a weight average molecular weight of about 30,000 to 400,000, preferably about 50,000 to 350,000. The terpolymer has its components in the molar ratio of MA:AVE:IB of about 1:0.4-0.9:0.1-0.6, preferably about 1:0.5-0.8-0.2-0.5.Type: GrantFiled: July 25, 1990Date of Patent: August 6, 1991Assignee: GAF Chemicals CorporationInventors: Mohammed Tazi, Robert B. Login, Yoon T. Kwak, Balgopal Gangadharan, Rama K. Haldar
-
Patent number: 4910247Abstract: A composition containing an adhesive suitable for affixing dentures or ostomy devices to a mucous membrane, which adhesive is a mixture composed of(a) 75-25 wt. % of a blend comprising a divalent calcium salt and a monovalent sodium salt of a lower alkyl vinyl ether/maleic acid copolymer wherein the concentration of Ca is between about 10 and 15 wt. % of the blend; Na is between about 1.5 and about 4 wt. % of the blend and --COOH is between about 9 and about 25 wt. % of the blend;(b) 0-10 wt. % of a lower alkyl vinyl ether/maleic acid auxiliary metal salt wherein said metal is divalent magnesium and/or monovalent potassium and wherein said auxiliary metal represents between about 1.5 and about 15 wt. % of said auxiliary metal salt compound and(c) 25-75 wt. % of a stearic acid metal salt wherein said metal salt is magnesium stearate containing from 0% to about 75% sodium stearate.The invention also relates to the use of said composition as an adhesive used in association with mucous membranes.Type: GrantFiled: March 27, 1989Date of Patent: March 20, 1990Assignee: GAF Chemicals CorporationInventors: Rama K. Haldar, Balgopal Gangadharan, Ratan K. Chaudhuri