Methods for the administration of certain VMAT2 inhibitors
Provided are methods of administering a vesicular monoamine transport 2 (VMAT2) inhibitor chosen from valbenazine and (+)-α-3-isobutyl-9,10-dimethoxy-1,3,4,6,7,1 1 b -hexahydro-2H-pyrido[2,1-a]isoquinolin-2-ol, or a pharmaceutically acceptable salt and/or isotopic variant thereof, to a patient in need thereof wherein the patient is also being administered digoxin.
1. A method for treating a patient with a hyperkinetic movement disorder, wherein the hyperkinetic movement disorder is chorea associated with Huntington's disease, and wherein the patient is also being co-administered digoxin, comprising:
a. orally administering to the patient a therapeutically effective amount of a vesicular monoamine transporter 2 (VMAT2) inhibitor chosen from (S)-2-amino-3-methyl-butyric acid (2R,3R,11bR)-3-isobutyl-9,10-dimethoxy-1,3,4,6,7,11b-hexahydro-2H-pyrido[2,1-a]isoquinolin-2-yl ester and pharmaceutically acceptable salts thereof;
b. monitoring the digoxin concentration in the patient's blood; and
c. reducing the dose of digoxin when the digoxin exposure in the patient's blood is increased as compared with the digoxin level in a patient who is administered digoxin alone.
2. The method of claim 1 , wherein the digoxin exposure is measured as the area under the plasma concentration versus time curve from 0 hours extrapolated to infinity or measured as the maximum observed blood plasma concentration (C max ) at the time of maximum plasma concentration (t max ).
3. The method of claim 1 , wherein the increased digoxin exposure increases the risk of one or more exposure-related adverse reactions.
4. The method of claim 1 , further comprising monitoring the patient for one or more exposure-related adverse reactions.
5. The method of claim 4 , wherein the one or more exposure-related adverse reactions is selected from headache, anxiety, insomnia, diarrhea, restlessness, and abnormal dreams.
6. The method of claim 1 , further comprising obtaining a baseline serum digoxin concentration prior to administering to the patient the therapeutically effective amount of the VMAT2 inhibitor.
7. The method of claim 1 , wherein the VMAT2 inhibitor is administered in the form of a tablet or capsule.
8. The method of claim 1 , wherein the VMAT2 inhibitor is a pharmaceutically acceptable salt of (S)-2-amino-3-methyl-butyric acid (2R,3R,11bR)-3isobutyl-9,10-dimethoxy-1,3,4,6,7,11b-hexahydro-2H-pyrido[2,1-a]H-pyrido[2,1a]isoquinolin-2-yl ester.
9. The method of claim 1 , wherein the VMAT2 inhibitor is a ditosylate salt of (S)-2-amino-3-methyl-butyric acid (2R,3R,11bR)-3-isobutyl-9,10-dimethoxy-1,3,4,6,7,11b-hexahydro-2H-pyrido[2,1-a]isoquinolin-2-yl ester.
10. The method of claim 1 , wherein the therapeutically effective amount is an amount equivalent to about 40 mg as measured by (S)-2-amino-3-methyl-butyric acid (2R,3R,11bR)-3-isobutyl-9,10-dimethoxy-1,3,4,6,7,11b-hexahydro -2H-pyrido[2,1-a]isoquinolin-2-yl ester once daily for one week, and an amount equivalent to about 80 mg as measured by (S)-2-amino-3-methyl-butyric acid (2R,3R,11bR)-3-isobutyl-9,10-dimethoxy-1,3,4,6,7,11b-hexahydro-2H-pyrido[2,1-a]isoquinolin-2-yl ester once daily after one week.
11. The method of claim 1 , wherein the therapeutically effective amount is an amount equivalent to between about 20 mg to about 160 mg as measured by (S)-2-amino-3-methyl-butyric acid (2R,3R,11bR)-3-isobutyl-9,10-dimethoxy-1,3,4,6,7,11b-hexahydro-2H-pyrido[2,1-a]isoquinolin-2-yl ester once daily.
12. The method of claim 1 , wherein the therapeutically effective amount is an amount equivalent to about 40 mg as measured by (S)-2-amino-3-methyl-butyric acid (2R,3R,11bR)-3-isobutyl-9,10-dimethoxy-1,3,4,6,7,11b-hexahydro -2H-pyrido[2,1-a]isoquinolin-2-yl ester once daily.
13. The method of claim 1 , wherein the therapeutically effective amount is an amount equivalent to about 60 mg as measured by (S)-2-amino-3-methyl-butyric acid (2R,3R,11bR)-3-isobutyl-9,10-dimethoxy-1,3,4,6,7,11b-hexahydro -2H-pyrido[2,1-a]isoquinolin-2-yl ester once daily.
14. The method of claim 1 , wherein the therapeutically effective amount is an amount equivalent to about 80 mg as measured by (S)-2-amino-3-methyl-butyric acid (2R,3R,11bR)-3-isobutyl-9,10-dimethoxy-1,3,4,6,7,11b-hexahydro -2H-pyrido[2,1-a]isoquinolin-2-yl ester once daily.
15. The method of claim 1 , wherein the co-administration of the VMAT2 inhibitor with digoxin increases digoxin levels because of inhibition of intestinal P-glycoprotein (P-gp) by the VMAT2 inhibitor.