This document summarizes drug excretion, which is the removal of drugs from the body through various routes. The major routes of excretion are the kidneys (renal excretion), bile/liver (biliary secretion), lungs (pulmonary excretion), and feces. Renal excretion occurs through glomerular filtration, tubular reabsorption, and tubular secretion in the kidneys. Biliary secretion involves the active transport of drugs from liver cells into bile. Pulmonary excretion eliminates gaseous and volatile substances through exhaled breath. Factors like a drug's properties, age, disease states, and urine pH can impact the rate of excretion.

1. DRUG EXCRETION
PRAJJWAL, M.Pharma
ADVANCE PHARMACOLOGY-1
BADDI UNIVERSITY OF EMERGING SCIENCE AND TECHNOLOGY, BADDI

2. I N D E X
Introduction
Organ Involved
Renal Excretion
Biliary Secretion
Pulmonary & Faecal Excretion
Other Excretion
Factors Affecting Drug Excretion
Reference

3. INTRODUCTION
 Drug excretion is the removal of drugs from the body, either as a
metabolite or a unchanged drug.
(OR)
 It is a process in which drug or metabolite are irreversibly transferred
from internal to external environment through renal or non-renal route.

4. ORGAN INVOLVED
• Major Route
 Kidney(Renal)
 Biliary/Hepatic
 Pulmonary
 Faecal
• Minor Route
 Saliva
 Skin, sweat
 Tears
 Breast milk
 Vaginal fluid

5. RENAL EXCRETION
 The greatest proportion of drug excretion
occurs through kidney.
 One-fifth of the plasma reaching to the kidney
Is filtered through the pores in the glomerular cell
membrane.
 Substance not bounded to the plasma protein
can easily pass through the membrane.
• Eliminate
• Don’t cross the membrane
Polar/water-
solubal/ionised
• Re-absorbed
• Cross the membrane
Non-polar/Lipid-
solubal/Unionise
d

6. RENAL EXCRETION
 Renal excretion determined by three processos;
✓ Glomerular Filtration:
* Glomerular capillaries have large pores.
* Lipid soluble drugs are filtered through it.
* Glomerular filteration depends upon; Molecular size, Plasma protein binding, Renal
blood flow.
* Normal GFR is 120ml/min.
✓ Tubular Re-absorption:
*Process by which the nephron removes water and solute from the tubular fluid and
return them to circulating blood.
* Occurs by passive diffusion and depends on; Lipid solubility, pH of urine, pKa of drug.
✓ Tubular Secretion:
* Occurs via active diffusion.
* Important for water removal and acid-base balance.

7. BILIARY SECRETION
 It involves active secretion of drug molecules from
hepatocytes into the bile.
 Bile transport the drug/metabolite to the gut,where
It excreted.
 Drugs excreted through bile are large with the
molecular weight <300g/mol.

8. PULMONARY EXCRETION
 The lung is the major organ of excretion for gaseous and volatile substances.
 The breathalyzer test is based on a quantitative pulmonary excretion of ethanol.
 Most of the gaseous anesthetics are extensively eliminated in expired air.
FAECAL EXCRETION
 Orally absorbed drug which aren’t absorbed.
e.g. Magnesium sulphate, Neomycin.

9. OTHER EXCRETION
 Skin,
1. Arsenicc and heavy metal like mercy gets eliminated by skin through sweating.
2. Griseofulvin secreted through keratin precursor cells.
 Hair follicles: iodide, mercury, arsenic
 Saliva: Iodine, potassium iodide, lithium
 Sweat: Rifampicin, urea derivatives

10. FACTORS AFFECTING EXCRETION OF DRUG
 Physiological properties of drug;
1. Molecular weight
2. Lipid solubility
3. Degree of ionisation
4. Volume of distribution
 Biological factos; e.g. Age
 Disease state
 Urine pH

11. REFERENCE
1. https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/drug-
excretion
2. https://www.pharmacologyeducation.org/pharmacology/drug-excretion
3. https://en.m.wikipedia.org/wiki/Reabsorption#:~:text=In%20renal%20physiology%2C%20reabs
orption%20or,them%20to%20the%20circulating%20blood.
4. https://www.sciencedirect.com/topics/medicine-and-dentistry/biliary-excretion
5. https://www.boomer.org/c/p1/Ch16/Ch1604.html#:~:text=The%20lung%20is%20the%20major,e
xtensively%20eliminated%20in%20expired%20air.
6. http://www.slideshare.net/nasertadvi/drug-excretion-new?from_m_app=android

12. THANK YOU