The Biopharmaceutics Classification System is a system to differentiate the drugs on the basis of their solubility and permeability. This system restricts the prediction using the parameters

solubility In chemistry, solubility is the ability of a substance, the solute, to form a solution with another substance, the solvent. Insolubility is the opposite property, the inability of the solute to form such a solution. The extent of the solub ...

and intestinal permeability. The solubility classification is based on a

United States Pharmacopoeia The ''United States Pharmacopeia'' (''USP'') is a pharmacopeia (compendium of drug information) for the United States published annually by the United States Pharmacopeial Convention (usually also called the USP), a nonprofit organization that ...

(USP) aperture. The intestinal permeability classification is based on a comparison to the intravenous injection. All those factors are highly important because 85% of the most sold drugs in the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territori ...

and

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a subcontinent of Eurasia and it is located entirel ...

are orally administered .

BCS classes

Biopharmaceutics Classification System (BCS)

According to the Biopharmaceutical Classification System (BCS) drug substances are classified to four classes upon their solubility and permeability: *Class I - high permeability, high

** Example:

metoprolol Metoprolol, sold under the brand name Lopressor, among others, is a selective β1 receptor blocker medication. It is used to treat high blood pressure, chest pain due to poor blood flow to the heart, and a number of conditions involving an a ...

, paracetamol ** Those compounds are well absorbed and their absorption rate is usually higher than excretion. *Class II - high permeability, low solubility ** Example:

glibenclamide Glibenclamide, also known as glyburide, is an antidiabetic medication used to treat type 2 diabetes. It is recommended that it be taken together with diet and exercise. It may be used with other antidiabetic medication. It is not recommended f ...

bicalutamide Bicalutamide, sold under the brand name Casodex among others, is an antiandrogen medication that is primarily used to treat prostate cancer. It is typically used together with a gonadotropin-releasing hormone (GnRH) analogue or surgical remo ...

ezetimibe Ezetimibe is a medication used to treat high blood cholesterol and certain other lipid abnormalities. Generally it is used together with dietary changes and a statin. Alone, it is less preferred than a statin. It is taken by mouth. It is also ...

, aceclofenac ** The

bioavailability In pharmacology, bioavailability is a subcategory of absorption and is the fraction (%) of an administered drug that reaches the systemic circulation. By definition, when a medication is administered intravenously, its bioavailability is 100%. Ho ...

of those products is limited by their solvation rate. A correlation between the ''

in vivo Studies that are ''in vivo'' (Latin for "within the living"; often not italicized in English) are those in which the effects of various biological entities are tested on whole, living organisms or cells, usually animals, including humans, and ...

'' bioavailability and the ''

in vitro ''In vitro'' (meaning in glass, or ''in the glass'') studies are performed with microorganisms, cells, or biological molecules outside their normal biological context. Colloquially called " test-tube experiments", these studies in biology ...

'' solvation can be found. *Class III - low permeability, high solubility ** Example: cimetidine ** The absorption is limited by the permeation rate but the drug is solvated very fast. If the formulation does not change the permeability or gastro-intestinal duration time, then class I criteria can be applied. *Class IV - low permeability, low solubility ** Example:

Bifonazole Bifonazole (trade name Canespor among others) is an imidazole antifungal drug used in form of ointments. It was patented in 1974 and approved for medical use in 1983. There are also combinations with carbamide for the treatment of onychomycos ...

** Those compounds have a poor bioavailability. Usually they are not well absorbed over the intestinal mucosa and a high variability is expected.

Definitions

The drugs are classified in BCS on the basis of solubility, permeability, and dissolution. Solubility class boundaries are based on the highest dose strength of an immediate release product. A drug is considered highly soluble when the highest dose strength is soluble in 250 ml or less of aqueous media over the pH range of 1 to 7.5. The volume estimate of 250 ml is derived from typical bioequivalence study protocols that prescribe administration of a drug product to fasting human volunteers with a glass of water. Permeability class boundaries are based indirectly on the extent of absorption of a drug substance in humans and directly on the measurement of rates of mass transfer across human intestinal membrane. Alternatively non-human systems capable of predicting drug absorption in humans can be used (such as in-vitro culture methods). A drug substance is considered highly permeable when the extent of absorption in humans is determined to be 90% or more of the administered dose based on a mass-balance determination or in comparison to an intravenous dose. For dissolution class boundaries, an immediate release product is considered rapidly dissolving when no less than 85% of the labeled amount of the drug substance dissolves within 15 minutes using USP Dissolution Apparatus 1 at 100 RPM or Apparatus 2 at 50 RPM in a volume of 900 ml or less in the following media: 0.1 M HCl or simulated gastric fluid or pH 4.5 buffer and pH 6.8 buffer or simulated intestinal fluid.

References

External links

BCS guidance
of the

U.S. Food and Drug Administration The United States Food and Drug Administration (FDA or US FDA) is a federal agency of the Department of Health and Human Services. The FDA is responsible for protecting and promoting public health through the control and supervision of food ...

Pharmacological classification systems Pharmacy in the United States

BCS classes

Definitions

See also

References

Further reading

External links