Question

How do biological principles of membrane transport relate to the transport of drugs across the membrane? Please be specific in describing the different properties of drugs (polar, non-polar, large, small, charged, etc.)

Answer 1

The method of drugs cross membrane is by either active or passive diffusion. The most common method for drugs to cross the cell membrane is by passive diffusion. Drug molecules will diffuse down its concentration gradient without expenditure of energy by the cell. However the membranes are selectively permeable , so it has different effects on the rate of diffusion in different drug molecules.

In cellular biology , membrane transport refers to the collection of mechanisms that regulate the passage of solutes such as ions and small molecules through biological membranes , which are lipid bilayers that contain proteins embedded in them.

Polar molecules and large ions dissolved in water cannot diffuse freely across the plasma membrane due to the hydrophobic nature of the fatty acid tails of the phospholipids that make up the lipid bilayer . Hence no nonpolar molecules are transported by proteins in the form of transmembrane channels.