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Jump to navigationJump to searchCreated page with 'File:lighterstill.jpgright|frame ==Etymology== French & Latin; French, from Latin absorption-, absorptio, from absorbēre *Date: [http:/...'
[[File:lighterstill.jpg]][[File:Cellularabsorption1.jpg|right|frame]]
==Etymology==
French & Latin; French, from [[Latin]] absorption-, absorptio, from absorbēre
*Date: [http://www.wikipedia.org/wiki/18th_Century 1741]
==Definitions==
*1 a : the [[process]] of absorbing or of being absorbed — compare adsorption
:b : interception of [[radiant]] [[energy]] or [[sound]] [[waves]]
*2 : entire occupation of the [[mind]] <absorption in his [[work]]>
==Description==
In pharmacology (and more specifically pharmacokinetics), '''absorption''' is the movement of a [[drug]] into the bloodstream.
Absorption involves several [[phases]]. First, the [[drug]] needs to be administered via some route of administration (oral, via the skin, etc.) and in a specific dosage form such as a tablet, capsule, and so on.
In other situations, such as [http://en.wikipedia.org/wiki/Intravenous_therapy intravenous therapy], intramuscular injection, [http://en.wikipedia.org/wiki/Nasogastric_intubation enteral nutrition] and others, absorption is even more straight-forward and there is less variability in absorption and bioavailability is often near 100%.
Absorption is a primary [[focus]] in [http://en.wikipedia.org/wiki/Drug_development drug development] and [http://en.wikipedia.org/wiki/Medicinal_chemistry medicinal chemistry], since the drug must be absorbed before any medicinal [[effects]] can take place. Moreover, the drug's pharmacokinetic profile can be easily and significantly changed by [[adjusting]] factors that [[affect]] absorption.
==Dissolution==
In the most [[standard]] situation, a tablet is ingested and passes through the [http://en.wikipedia.org/wiki/Esophagus esophagus] to the [http://en.wikipedia.org/wiki/Stomach stomach]. Because the stomach is an aqueous [[environment]], this is the first place where a tablet will dissolve.
The rate of dissolution is a key target for controlling the duration of a [[drug]]'s [[effect]], and as such, several dosage forms that contain the same active ingredient may be available, differing only in the rate of dissolution. If a drug is supplied in a form that is not readily dissolved, the drug may be released more [[gradually]] over time with a longer duration of [[action]]. Having a longer duration of action may improve [http://en.wikipedia.org/wiki/Compliance_(medicine) compliance] since the medication will not have to be taken as often. Additionally, slow-release dosage forms may maintain concentrations within an acceptable therapeutic range over a long period of time, as opposed to quick-release dosage forms which may result in sharper peaks and troughs in serum concentrations.
The rate of dissolution is described by the [http://en.wikipedia.org/wiki/Arthur_Amos_Noyes Noyes]-[http://en.wikipedia.org/wiki/Willis_Rodney_Whitney Whitney] equation as shown below:
[[File:Absorption.jpg]]
Where:
:[[File:Absorption_2.jpg]]
* A is the [http://en.wikipedia.org/wiki/Surface_area surface area] of the solid.
* C is the [[concentration]] of the solid in the bulk dissolution [[medium]].
* Cs is the concentration of the solid in the [[diffusion]] layer surrounding the solid.
* D is the diffusion [http://en.wikipedia.org/wiki/Coefficient coefficient].
* L is the diffusion layer thickness.
As can be inferred by the Noyes-Whitney equation, the rate of dissolution may be [[modified]] primarily by altering the surface area of the solid. The surface area may be [[adjusted]] by altering the [[particle]] size (e.g. [http://en.wikipedia.org/wiki/Micronization micronization]). The rate of dissolution may also be altered by choosing a suitable [http://en.wikipedia.org/wiki/Polymorphism_(materials_science) polymorph] of a compound. Specifically, [[crystalline]] forms dissolve slower than amorphous forms.
Also, coatings on a tablet or a pellet may act as a barrier to reduce the rate of dissolution. Coating may also be used to modify where dissolution takes place. For example, [http://en.wikipedia.org/wiki/Enteric_coating enteric coatings] may be applied to a drug, so that the coating only dissolves in the basic environment of the intestines. This will prevent release of the drug before reaching the intestines.
Since solutions are already dissolved, they do not need to undergo dissolution before being absorbed.[http://en.wikipedia.org/wiki/Absorption_%28pharmacokinetics%29]
[[Category: Chemistry]]
==Etymology==
French & Latin; French, from [[Latin]] absorption-, absorptio, from absorbēre
*Date: [http://www.wikipedia.org/wiki/18th_Century 1741]
==Definitions==
*1 a : the [[process]] of absorbing or of being absorbed — compare adsorption
:b : interception of [[radiant]] [[energy]] or [[sound]] [[waves]]
*2 : entire occupation of the [[mind]] <absorption in his [[work]]>
==Description==
In pharmacology (and more specifically pharmacokinetics), '''absorption''' is the movement of a [[drug]] into the bloodstream.
Absorption involves several [[phases]]. First, the [[drug]] needs to be administered via some route of administration (oral, via the skin, etc.) and in a specific dosage form such as a tablet, capsule, and so on.
In other situations, such as [http://en.wikipedia.org/wiki/Intravenous_therapy intravenous therapy], intramuscular injection, [http://en.wikipedia.org/wiki/Nasogastric_intubation enteral nutrition] and others, absorption is even more straight-forward and there is less variability in absorption and bioavailability is often near 100%.
Absorption is a primary [[focus]] in [http://en.wikipedia.org/wiki/Drug_development drug development] and [http://en.wikipedia.org/wiki/Medicinal_chemistry medicinal chemistry], since the drug must be absorbed before any medicinal [[effects]] can take place. Moreover, the drug's pharmacokinetic profile can be easily and significantly changed by [[adjusting]] factors that [[affect]] absorption.
==Dissolution==
In the most [[standard]] situation, a tablet is ingested and passes through the [http://en.wikipedia.org/wiki/Esophagus esophagus] to the [http://en.wikipedia.org/wiki/Stomach stomach]. Because the stomach is an aqueous [[environment]], this is the first place where a tablet will dissolve.
The rate of dissolution is a key target for controlling the duration of a [[drug]]'s [[effect]], and as such, several dosage forms that contain the same active ingredient may be available, differing only in the rate of dissolution. If a drug is supplied in a form that is not readily dissolved, the drug may be released more [[gradually]] over time with a longer duration of [[action]]. Having a longer duration of action may improve [http://en.wikipedia.org/wiki/Compliance_(medicine) compliance] since the medication will not have to be taken as often. Additionally, slow-release dosage forms may maintain concentrations within an acceptable therapeutic range over a long period of time, as opposed to quick-release dosage forms which may result in sharper peaks and troughs in serum concentrations.
The rate of dissolution is described by the [http://en.wikipedia.org/wiki/Arthur_Amos_Noyes Noyes]-[http://en.wikipedia.org/wiki/Willis_Rodney_Whitney Whitney] equation as shown below:
[[File:Absorption.jpg]]
Where:
:[[File:Absorption_2.jpg]]
* A is the [http://en.wikipedia.org/wiki/Surface_area surface area] of the solid.
* C is the [[concentration]] of the solid in the bulk dissolution [[medium]].
* Cs is the concentration of the solid in the [[diffusion]] layer surrounding the solid.
* D is the diffusion [http://en.wikipedia.org/wiki/Coefficient coefficient].
* L is the diffusion layer thickness.
As can be inferred by the Noyes-Whitney equation, the rate of dissolution may be [[modified]] primarily by altering the surface area of the solid. The surface area may be [[adjusted]] by altering the [[particle]] size (e.g. [http://en.wikipedia.org/wiki/Micronization micronization]). The rate of dissolution may also be altered by choosing a suitable [http://en.wikipedia.org/wiki/Polymorphism_(materials_science) polymorph] of a compound. Specifically, [[crystalline]] forms dissolve slower than amorphous forms.
Also, coatings on a tablet or a pellet may act as a barrier to reduce the rate of dissolution. Coating may also be used to modify where dissolution takes place. For example, [http://en.wikipedia.org/wiki/Enteric_coating enteric coatings] may be applied to a drug, so that the coating only dissolves in the basic environment of the intestines. This will prevent release of the drug before reaching the intestines.
Since solutions are already dissolved, they do not need to undergo dissolution before being absorbed.[http://en.wikipedia.org/wiki/Absorption_%28pharmacokinetics%29]
[[Category: Chemistry]]
