This document discusses therapeutic drug monitoring of digoxin. Digoxin is a cardiac glycoside derived from Digitalis lanata and Digitalis purpurea. It has a steroidal structure with three digitoxose units bound by a glycosidic linkage. Digoxin is indicated for heart failure and atrial fibrillation with a dose of 0.125-0.25 mg tablets or 0.1-0.25 mg/mL injections. Therapeutic drug monitoring of digoxin is important due to its narrow therapeutic index and variability in patient response. Radioimmunoassay is commonly used to measure digoxin levels via competitive binding of labeled and unlabeled antigen to antibodies.

1. TDM OF DIGOXIN
By,
Surya Prakash singh
ROLL: 12117D3003
pharmD IV th
year

2. IT'S A CARDIAC GLYCOSIDE
THE SOURCE'S ARE
DIGITALIS LANNATA
DIGITALIS PURPUREA
ITS STRUCTURE
Basic cardenolide with
three digitoxose untis
bound to streroidal ring
by a glycosidic linkage.
DRUG PROFILE OF DIGOXIN

3. DOSE AND INDICATION
DOSE:
Tablet : 0.125 - 0.25 mg TAB
Injection solution : 0.1mg/ML - 0.25mg/ML
INDICATION:
heart failure
&
atrial fibrillation.

4. ABSORPTION
BA: 55-90%
ONSET OF ACTION
PO : WITHIN 2 HR
IV : WITHIN 30 MIN
DURATION OF ACTION : 3-4 DAYS
PEAK PLASMA TIME : 1 HR

5. DISTRIBUTION
PROTEIN BOUND: 20-25%
VD : 4 – 7 L/KG
METABOLISM
LIVER
ELIMINATIOIN
T 1/2 : 1-3 DAYS
EXCRETION
URINE : 80%
FEACES: 10-15%

6. MECHANISM OF ACTION OF DIGOXIN

7. OTHER EFFECTS :
Neuro hormonal effects
• Decrease sympathic out flow
• Increase parasympathetic outflow
• Improve baro receptor functioning
DECREASE HEART
RATE
(NEGATIVE
CHRONOTROPIC
EFFECT)

11. REASONS FOR TDM OF
DIGOXIN ??????

13. METHOD OF ASSAY
Radioimmunoassay (RIA) involves the quantitation of drug using a
radioactive probe by measuring the radioactivity correlated to
amount of drug.
The technique was introduced in 1960 by Berson and Yalow

14. Mixture of radioactive labeled
antigen "hot"
+
antibody
Adding the sample unlabeled
antigen (drug)"cold"
The unlabelled antigen
displaces the labeled ones
(Ag-Ab)Complexes are
removed
Supernatant remains are
analyzed

15. Gamma Counter

16.  From these data, a
standard binding
curve, like the one
shown in red, can
be drawn.

18. OTHER METHODS OF ASSAYS
 Nucleic acid labeling
 Fluorescence labeling
 ELISA
 High throughput screening wells coated with
antibodies.

19. THANK YOU