We are continuing our BCS topic, looking at each BCS class in more detail and discussing associated compounding technologies. This week, we will look at Class 2, High Permeability, Low Solubility drugs.

The bioavailability of Class 2 drugs is limited by their rate of solvation. They have a high absorption number but a low dissolution number. Generally, the absorption for Class 2 drugs is slower than Class 1 drugs and occurs over a longer period of time.

List of Class 2 Drugs

A list of Class 2 drugs gathered from several sources includes the following:

Compounding Considerations for BCS Class 2 Drugs

This class involves drugs in which the solubility or dissolution rate is limiting, thus potentially significantly affecting absorption and bioavailability.

Particularly for Class 2 drugs, an increase in the solubility and dissolution rate will result in more efficient drug absorption since Class 2 drugs are well absorbed from the GI tract once in solution due to their relatively high lipophilicity.

Methods used in compounding and formulating this class can include:

• Micronization
• Solvent deposition (deposition of poorly soluble drugs on inert material)
• Stabilization of high-energy states (including lyophilized fast-melt systems)
• Use of surfactants
• Forming emulsion or microemulsion systems with the lipophilic drug in the internal phase
• Forming nanoemulsions, nanosuspensions, and nanocrystals
• Forming solid dispersions
• Forming inclusion complexes using complexing agents such as cyclodextrins by kneading, steam granulating, co-precipitating, freeze drying, and spray drying
• Forming polymer strip films
• Soft-gelatin capsule formulation
• Using hot-melt extrusion with a water-soluble carrier
• Use of solvates and hydrates
• Use of salt of weak acids and weak bases
• Buffering the pH of the microenvironment

Next week, we will look in more detail at Class 3.

Loyd V. Allen, Jr., PhD, RPh
Editor-in-Chief
International Journal of Pharmaceutical Compounding
Remington: The Science and Practice of Pharmacy Twenty-second edition

IJPC Now on Facebook and Youtube

Become a fan of the IJPC Facebook page and share ideas, photos, and keep up to date with the latest compounding information - http://www.facebook.com/IJPCompounding

Learn about the Journal's new multi-media features and view our growing collection of educational and training videos at www.ijpc.com/video or by subscribing to our Youtube channel at https://www.youtube.com/user/IJPCompounding.

Did You Know ...

"�that from the seat of a tractor:

• Life is simpler when you plow around the stump?
• If you get to thinkin' you're a person of influence, try orderin' somebody else's dog around?
• If you find yourself in a hole, the first thing to do is to stop diggin'?

Tip of the Week

"I learned everything I need to know in kindergarten!"

Really? Many in our profession say "I learned everything I need to know in pharmacy school"! We all know that is not true. In fact, things in pharmacy are changing rapidly and one gets "out of touch" if not keeping up with at least weekly reading for a few hours. When new things come along, they scratch their heads and say, "when did that happen?"

I am reminded of a saying I used to have on the wall:

    Some people make things happen,
    Some people watch things happen,
    Some people wonder "what happened"?

I hope we are all in the first group!

Looking Back

His Rose is wed,
His Violet blew,
But his sugar is sweet,
Since he took this cue.
     Burma Shave