Claims for Patent: 4,057,617

Summary for Patent: 4,057,617

Title:	Method of labeling proteins with technetium
Abstract:	Fibrinogen is labeled with .sup.99m Technetium by reducing pertechnetate at a pH of about 11-12 using a solution of stannous chloride in the presence of a base, then contacting the reduced pertechnetate with fibrinogen. Unwanted lower molecular weight impurities are removed; the labeled product suitably adjusted to a pH of 7-8 to form an injectable isotopic tracer solution.
Inventor(s):	Abramovici; Jean (Ixelles, 1050 Brussels, BE), Ermans; Andre Marie (Ixelles, 1050 Brussels, BE), Jeghers; Omer (4561 Neufchateau, BE)
Assignee:
Application Number:	05/635,774
Patent Claims:	1. A method of labeling fibrinogen with 99m technetium comprising reducing pertechnetate at a pH of about 11 to 12 by the addition of a solution of acetic acid and stannous chloride in the presence of a base, contacting the thus reduced pertechnetate with fibrinogen thereby labeling the fibrinogen with 99m technetium and purifying the resulting mixture by removing unwanted degradation products of the fibrinogen and non-bound technetium. 2. A method according to claim 1 wherein the pertechnetate is reduced at a pH of the order of about 11.6. 3. A method according to claim 1 wherein the purification includes separating the labeled fibrinogen from substances having a molecular weight less than 100,000. 4. A method according to claim 1 wherein the purification includes separating from the mixture substances having a molecular weight less than 300,000. 5. A method according to claim 1 wherein the purification includes first separating free technetium and technetium bound to molecules having a molecular weight less than 100,000, and in a subsequent step separating molecules having a molecular weight less than 300,000. 6. A method according to claim 3 wherein the mixture is conveyed over a suitable membrane through which substances to be separated from the mixture pass. 7. A method according to claim 1 wherein the pertechnetate is contained in physiological medium. 8. A method according to claim 1 wherein an injectable fibrinogen of human origin is used. 9. A method according to claim 1 wherein lyophilized fibrinogen with buffer salts is used including dissolving the fibrinogen in water to yield a fibrinogen solution, mixing the fibrinogen solution with the reduced pertechnetate for about 15 minutes at ambient temperature, and reducing the pH of the mixture of fibrinogen and reduced pertechnetate to a final pH of 7 to 8. 10. A method according to claim 9 wherein the fibrinogen solution is dialysed to eliminate the buffer salts prior to mixing with the reduced pertechnetate. 11. A method according to claim 9 wherein the final mixture is adjusted to a pH of the order of about 7.4. 12. A method according to claim 9 wherein the pH of the mixture is reduced to the desired value by adding an aqueous solution of sodium citrate and citric acid to produce an injectable solution. 13. A method according to claim 9 wherein prior to the purification step any colloidal substances, precipitated substances or both occurring during the lowering of the pH of the mixture are separated. 14. A method according to claim 13 wherein the mixture is passed through a filter which retains thereon substances to be separated and removed from the mixture. 15. A method according to claim 10 wherein the fibrinogen is labeled in a nitrogen atmosphere. 16. A method of binding 99m technetium to fibrinogen to produce fibrinogen labeled with 99m technetium comprising the steps of: 1. reducing pertechnetate at a pH of about 11 to 12 by the addition thereto of a solution of acetic acid and stannous chloride in the presence of a base; 2. contacting the thus reduced pertechnetate with fibrinogen thereby labeling the fibrinogen with 99m technetium; 3. removing unbound technetium and technetium bound to molecules having a molecular weight less than 100,000, and in a second purification step; 4. removing all molecules having a molecular weight less than 300,000, thereby producing a product having about 90% or more of the 99m technetium bound to the fibrinogen. 17. A method according to claim 16 wherein at least about 98% of the technetium is bound to the fibrinogen. 18. A method of producing an injectable solution of 99m technetium labeled fibrinogen comprising the steps of: 1. reducing pertechnetate at a pH of about 11-12 by adding a solution of acetic acid and stannous chloride in the presence of a base; 2. dissolving lyophilized fibrinogen including buffer salts associated therewith in water yielding a fibrinogen solution; 3. mixing the fibrinogen solution of step (2) with the reduced pertechnetate of step (1) at ambient temperature for about 15 minutes; 4. lowering the pH of the solution of step (3) to a final pH of about 7-8 by the addition of an aqueous solution of sodium citrate and citric acid; and 5. removing fibrinogen degradation products and non-bound technetium, thereby producing an injectable solution of fibrinogen labeled with 99m technetium.

Details for Patent 4,057,617

Applicant	Tradename	Biologic Ingredient	Dosage Form	BLA	Approval Date	Patent No.	Expiredate
Csl Behring Gmbh	RIASTAP	fibrinogen concentrate (human)	For Injection	125317	January 16, 2009	4,057,617	1995-05-15
Octapharma Pharmazeutika Produktionsges.m.b.h.	FIBRYGA	fibrinogen (human)	For Injection	125612	June 07, 2017	4,057,617	1995-05-15