2. Patients with ESRD or who have been
intoxicated due to overdose of a drug may require
supported treatment to remove accumulated
drugs.
Methods:
Dialysis
Hemofiltration
Hemoperfusion.
Objective:
Rapidly remove undesirable drugs and
metabolites without disturbing the fluid and electrolyte
balance in the patient.
3. Artificial Process, acculmulation of drug
removed by diffusion into dialysis fluid.
Two Methods:
Peritoneal Dialysis.
Hemodialysis.
4. Helps to clean the blood and remove
excess of water in the body – peritoneal
Membrane in the abdomen.
A catheter inserted in peritoneal cavity,
dialysis fluid enters into the peritoneal
cavity via tube -> filters blood and
remove waste products from the body.
Two Types
CAPD(Continous Ambulatory Peritoneal Dialysis)))
APD (Automated Peritoneal Dialysis)
5. Fluid flows in and out of the body using
gravity.
Over time, waste and fluid build up in the
blood which slowly float across into
peritoneal membrane by diffusion and
exchange remove dialysis fluid from the
peritoneal cavity and replaces with new fluid.
To be done everyday
1 Exchange takes 30 mins.
6. Solution is clear.
Check the solution type and % is correct.
Expiration date has not passed.
Volume is correct.
No leaks after gentle squeezing.
7. Machine does the exchange
Done by Dialysis team or taught to use .
FLUID AND DIALYSIS SOLUTION
Important to achieve right balance of water in body.
Determined in 3 ways.
Weight
BP
Swelling
Dialysis Solution
Dianeal (1.5%, 2.5%, 4.25%)
Neutroneal (1.1 %)
Extraneal (7.5%)
PRECAUTION
Infection
8. Process that uses artificial kidney to remove waste products
through the process called diffusion.
Artificial kidney contains a number of tubes with a semi
permeable lining, suspended in a tank filled with dialysing
fluid.
9. 1.
•One line connected to artery which is connected to one end of dialysis where
blood is collected from patient for filtration.
2.
•Waste Product from the blood passes into dialysing fluid by diffusion.
3.
•Purified Blood is pumped back into the vein which is connected to other end
of dialysis device.
10. Heparin is used to prevent blood clotting during dialysis.
It is much more effective method for rapid removal of drug (
overdose , poisoning) and preferred method in ESRD.
Dialysis may be required from every 2 days to 3 times a week,
one dialysis period is of 2-4 hrs depending on patient’s size,
weight and renal function.
CHARACTERISTICS OF DIALYSING MACHINE
Higher Blood flow rate.
Permeable dialysis membrane.
High Transmembrane pressure.
Important notes.
11. •Insoluble or fat soluble drugs are not solubilized.( eg
glutethimide – a water insoluble drug.)
Water Solubility
•Tightly bound protein are not dialysed. (eg
propranolol)
Protein Binding
•Mol Wt less than 500 are dialysed. ( eg Vancomycin is
poorly dialysed )
Molecular Weight
Drugs with large
volume of distribution
•Widely distributed drugs are dialysed slowly, drug
concentrated in tissues are difficult to remove by
dialysis.
12. In dialysis involving uremic patient receiving drug for therapy,
drug is removed depending on the flow rate of the blood to
the dialysis machine which is described by the term
Dialysance.
Defined by the equation :
ClD = Q(Ca –CV)
Ca
where, Ca = Drug Concentration in arterial blood.
CV =Drug Concentration in Venous blood.
Q= Rate of Blood flow to kidney.
ClD = Dialysance.
13. Removing the drugs by passing the blood
from the patient through an adsorbent
material and back to the patient.
Molecules which have greater affinity for the
materials will be removed.
14. Useful in accidental poisoning and drug
overdose.
Materials use:
◦ Activated Charcoal (both polar and non polar drugs)
◦ Amberlite resins (non polar organic molecules).
15. Affinity of the drug for the absorbent.
Surface area of the absorbent.
Absorptive capacity of the absorbent.
Rate of blood flow through the absorbent.
Equilibrium rate of the drug from the
peripheral tissue into the blood.
16. An alternative to hemodialysis and
hemoperfusion.
A process by which fluid, electrolytes, small
molecular weight substances are removed
from the blood using hollow artificial fibre.
Loss of water and electrolytes takes place,
that leads to production of ultrafiltrate. As a
result equal volume of fluid is replaced.
17. Synthetic, high flux(permeability), hollow fibre membrane.
Pore size 50000 da
High Surface Area ( 0.6-1.2 m2).
Notes
• Flow rate of 20-35 ml/kg/hr is usually required.
• No benefit shown with higher flow rate, more expensive.
• Although higher flow rate may be used if rapid solute
clearance is necessary.
18. Hemodialysis involves diffusion across a semipermeable membrane
Where as Hemofiltration is a convection process with loss of water
Due to ultrafiltration accompanied by convicted loss of salts.
19. The clearance of the drug depends on sieving coefficient and
ultrafiltration rate.
The sieving coefficient reflects the solute removal ability
during hemofiltration.
When S=1 solute passes freely through the membrane
whereas is S=0 solute is retained in plasma.
S is constant and independent of blood flow , so
Cl=S * Ultrafiltration rate
The Concentration of the drug in the ultrafiltrate is also equal
to the unbound drug concentration in the plasma , so,
amount of drug removed is given as :
Amount removed = CP + ∞ * rate of ultrafiltration
