p h and ion activated cdds

dept of pharmaceutics.dept of pharmaceutics. 11

pH-activated and ion-pH-activated and ion-activated controlled drug activated controlled drug

delivery systemdelivery system

ByBy

SHIVA KUMAR YSHIVA KUMAR Y Ist M. PharmacyIst M. Pharmacy

Dept. of PharmaceuticsDept. of Pharmaceutics K.L.E. University,K.L.E. University,

Belgaum.Belgaum.

dept of pharmaceutics. 2

Contents…Contents…

►pH-activated CDDSpH-activated CDDS► Ion-activated CDDSIon-activated CDDS►referencesreferences


pH-activated CDDSpH-activated CDDS► This type of DDS permits targeting the delivery of This type of DDS permits targeting the delivery of

a drug only in the region with a selected pH range.a drug only in the region with a selected pH range. Intestinal pH activated DDSIntestinal pH activated DDS

► It is fabricated by coating the drug containing core It is fabricated by coating the drug containing core with a pH sensitive polymer combination.with a pH sensitive polymer combination.

► A gastric fluid labile drug is protected by A gastric fluid labile drug is protected by encapsulating it inside a polymer membrane that encapsulating it inside a polymer membrane that resist the degradative action of gastric pH. such as resist the degradative action of gastric pH. such as the combination of ethyl cellulose and HMC the combination of ethyl cellulose and HMC phthalate.phthalate.

► The drug is release by drug dissolution and pore The drug is release by drug dissolution and pore channel diffusion mechanism.channel diffusion mechanism.


Gastric pH activated DDSGastric pH activated DDS


Ion-activated CDDSIon-activated CDDS

► Ionic or charged drug can be delivered by an Ionic or charged drug can be delivered by an this DDS.this DDS.

► Resins are used as the carrier for the drugsResins are used as the carrier for the drugs Types of ion-exchange resinsTypes of ion-exchange resinsCation-exchangersCation-exchangers: whose functional group : whose functional group

can undergo reaction with cations of a can undergo reaction with cations of a surrounding solution.surrounding solution.

Anion-exchangers:Anion-exchangers: whose functional group whose functional group can undergo reaction with anion of a can undergo reaction with anion of a surrounding solution.surrounding solution.


Preparations of resinsPreparations of resins► Cation exchange resin is prepared by the Cation exchange resin is prepared by the

copolymerisation of styrene-(l) and divinyl copolymerisation of styrene-(l) and divinyl bezene (ll).bezene (ll).

► Sulfonic acid group (-SOSulfonic acid group (-SO33--HH++) are introduced ) are introduced

in to most of the benzene rings of the in to most of the benzene rings of the styrene-divinyl benzene polymer.styrene-divinyl benzene polymer.

► Anion exchange resin is prepared by first Anion exchange resin is prepared by first chloromethylating the benzene rings of the chloromethylating the benzene rings of the three dimensional styrene-divinyl benzene three dimensional styrene-divinyl benzene copolymer to attach –CHcopolymer to attach –CH22Cl groups.Cl groups.

► Than causing these to react with a tertiary Than causing these to react with a tertiary amine, such as trimethylamine. amine, such as trimethylamine.


Drug suitable for the resinate Drug suitable for the resinate preparationpreparation

►Drug should have acidic or basic groups Drug should have acidic or basic groups in their chemical structure.in their chemical structure.

►The biological half-life should be 2-6 hrThe biological half-life should be 2-6 hr►The drug is to be absorbed from all The drug is to be absorbed from all

regions of the GIT. In the case of limited regions of the GIT. In the case of limited absorption zone, the bioavailability will absorption zone, the bioavailability will be insufficient.be insufficient.

►Drug should be stable sufficiently in the Drug should be stable sufficiently in the gastric juice.gastric juice.


important properties of ion-important properties of ion-exchange resinexchange resin

►Particle sizeParticle size►Porosity and swellingPorosity and swelling►Cross-linkageCross-linkage►stabilitystability►Acid base strengthAcid base strength


Mechanism and principleMechanism and principle


General preparation of drug General preparation of drug resinatesresinates

► Purification Purification ► Loading of drugLoading of drug1.1. Column processColumn process: A highly : A highly

concentrated drug solution is eluted concentrated drug solution is eluted through a bed or column of the resin through a bed or column of the resin until equilibrium is established.until equilibrium is established.

2.2. Batch processBatch process: The resin particles are : The resin particles are stirred with a large volume of stirred with a large volume of concentrated drug solution.concentrated drug solution.


Advantages Advantages

► Ion – exchange resinates of drug can Ion – exchange resinates of drug can help in reducing the dose.help in reducing the dose.

►Reduced fluctuations in blood and Reduced fluctuations in blood and tissue concentration level can be tissue concentration level can be achieved.achieved.

►Protection of drug form gastric Protection of drug form gastric enzymes.enzymes.

►Sustained or controlled release.Sustained or controlled release.


Limitations Limitations

►The release rate is proportional to the The release rate is proportional to the concentration of the ions present in concentration of the ions present in the area of administration.the area of administration.

►The release rate of drug can be The release rate of drug can be affected by variability in diet, water affected by variability in diet, water intake and individual intestinal intake and individual intestinal content.content.


ReferencesReferences

►Novel drug delivery systems by Y. W. Chein, Novel drug delivery systems by Y. W. Chein, 22ndnd edition, Dekkar series, pg. no. 195-224. edition, Dekkar series, pg. no. 195-224.

►Controlled and novel drug delivery by N. K. Controlled and novel drug delivery by N. K. Jain, C.B.S. Publishers and distributors, 1Jain, C.B.S. Publishers and distributors, 1stst edition, 1997.edition, 1997.

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p h and ion activated cdds

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