The phenomena of complex formation with protein is called as protein binding of drugs. Binding of drugs fall into two categories mainly : 1. binding of drugs to blood components like – plasma protein and blood cells 2.Binding of drugs to extracellular tissues proteins, fats,bones etc.

1. BY
MONIKA TARGHOTRA
M.PHARM

2.  It is defined as the hypothetical volume of body
fluid into which drug is dissolved or distributed.
 It is called as apparent volume. It can be
expressed as
APPARENT VOLUME = AMOUNT OF DRUG IN THE BODY
OF DISTRIBUTION PLASMA DRUG CONCENTRATION
Or
Vd = X
C

4. • The phenomena of complex formation with
protein is called as protein binding of drugs.
• Binding of drugs fall into two categories
mainly :
1. binding of drugs to blood components like
– plasma protein and blood cells
2.Binding of drugs to extracellular tissues
proteins, fats,bones etc.

5.  The main interaction of drug in the blood
compartment is with plasma protein which are
present in abundant amounts in large variety.
 The binding of drugs to plasma protein is
reversible.
 The extent of order of binding of drugs to various
plasma protein is :
albumin>alpha1-glycoprotein>lipoproteins>globulins

6. PROTEIN MOLECULAR CONCENTRATION DRUG THAT BIND
WEIGHT
Alpha-1
globulin
59,000 0.003-0.007 Steroids like
corticosteroids,
thyroxine and
cyanocobalamin
Alpha2
globulin
1,34,000 0.015-0.06 Vitamins A,D,E AND
K
And cupric ions
haemoglobi
n
64,500 11-16 Phenytoin,
pentobarbitol, and
phenothiazines

7. HUMAN SERUM
ALBUMIN
GLYCOPROTEIN LIPOPROTEIN BLOOD CELLS
Phenylbutazon
e
Naproxen
Phenytoin
indomethacin
Amitriptylinre
Lidocaine
Propanolol
Quinidine
Diclofenac
Cyclosporin A
Chlorpromazin
e
Arsenicals
Tetracycline
Chloroquine
Phenytoin

8. Drug Related
Factors
Protein
Related
Factors
Drug
Interactions
Patient
Related
Factors

9. Physiochemical characteristic of
the drug
Concentration of drug in the
body
Drug protein affinity

10.  Physiochemical properties of
protein
 Concentration of protein
 Number of binding sites in the
protein

11. Competition between drug for the
binding sites
Competition between drugs and
normal body constituents
Changes in protein molecule

12. • Age – neonates, infants and
elderly patients.
• Intersubject variants
• Disease state

13.  The value of association constant , Ka and the
number of binding sites N can be obtained by this
equation:
r = N Ka [D]
Ka[D]+ 1
 This equation can be explained by plotting it in
three ways as follows:
1) Direct Plot
2) Scatchard plot
3) Double Reciprocal plot

14.  Absorption
 Systemic solubility of drugs
 Distribution
 Tissue binding , volume of distribution and
drug storage
 Elimination
 Displacement interactions
 Diagnosis
 Drug targeting