This PPT includes what role does Dosage form impart on absorption. Why it is important in absorption. what should be its nature and type of dosage form.
1. Submitted to:
Dr. J. Josephine Leno Jenita
Asst. Professor,
Department of Pharmaceutics,
COPS, DSU
Banglore.
Presented by:
Arpitha.B. M
M Pharm (II SEM),
Department of Pharmaceutics,
COPS, DSU
Banglore
ROLE OF DOSAGE FORMS ON
ABSORPTION
2. Contents
• Nature and type of dosage form
• Solutions
• Emulsions
• Suspensions
• Powders
• Capsules
• Tablets
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3. Nature and type of DF
• Clinical success of a product not only depends upon a drug but also on the
proper selection of dosage form of that drug.
• For a given drug, a 2 to 5 fold or more difference could be observed in the
oral bioavailability of a drug depending on nature and type of DF.
• This difference is due to the relative rate at which a particular DF releases
the drug to the biologic membrane.
• The relative rate at which a drug from a dosage form is presented to the
body depends upon the complexity of DF.
• The more complex a dosage form, greater the number of rate – limiting
steps and greater the potential for bioavailability problems.
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4. COPS,DSU Department of Pharmaceutics Role of DFs on absorption 4
Course of events that occur following oral administration of various dosage forms
5. • The bioavailability of a drug from various DFs decrease in the
following order:
Solutions > Emulsions > Suspensions> Capsules> Tablets> Coated
tablets> enteric- coated tablets> sustained release products
• Solution- faster absorption
least potential for bioavailability problems
• Sustained release products- slow absorption
greater bioavailability risk
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6. SOLUTIONS
• A drug in a solution (syrups, elixirs, etc.) is most rapidly absorbed
since the major rate-limiting step (dissolution) is absent.
• Factors affecting bioavailabiliy of a drug from solution DF
-nature of solvent
-viscosity
-surfactant
-solubilizers
-stabilizers etc
• Factors that limit the formulation of a drug in solution form includes
-Stability, solubility, taste, cost of the product, etc.
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7. Emulsions
• Superior DF in administering poorly aqueous soluble, lipophilic drugs.
Eg:- indoxole (NSAID) – 3 fold increase over aqueous suspension.
• It provides large surface area of oil to the GIT for absorption of a drug.
• It avoids hepatic portal vein and first pass metabolism by direct
distribution of drug to into the lymphatic system (dug in oily phase is
emulsified and solubilised in the GIT by bile salts to form mixed micelles).
• Factors influencing drug absorption of emulsion
Surface area Surfactants
Interfacial tension Lipophilicity
Droplet size
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8. POWDERS
• They are not widely used nowadays due to handling and palatability
problems.
• Major factors to be considered in absorption of a drug from powders
are
particle size,
polymorphism,
wettability etc.
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9. CAPSULES
• Powders and granules are administered in hard gelatin capsules and
viscous fluids and oils in soft elastic shells.
• Factors in case of hard gelatin capsule include drug particle size,
density, polymorphism, intensity of packing and influence of diluents,
excipients and type of gelatin capsule.
• Other factors of importance include possible interaction between the
drug and the diluent (e.g. tetracycline- DCP) and between drug and
gelatin shell.
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10. TABLETS
• Compressed tablets are widely because of its convenience and cost
effective dosage forms.
• Compressed Tablets > Film Coated Tablets > Sugar Coated Tablets >
Enteric Coated Tablets > Sustained Release Products
• Same picture
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11. Factors to be considered in the absorption of drug from tablets are
• Effective surface area
• Dissolution
• Deaggregation
• Permeability
• Excipients & API
• Types of tablet
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Role of DFs on absorption
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12. COATED TABLETS:-
- Coating is another barrier that must first dissolve or disrupt to give
way to disintegration and dissolution of tablets.
- Coating two types
- 1. film coating :dissolves rapidly, thin and soluble.
- 2. sugar coating : tough and takes longer to dissolve.
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13. Enteric – coated tablets:
- They have great potential in creating bioavailability problems because
the coat dissolves only in the alkaline pH of the intestine.
- Factors that influence absorption of drug includes
- gastric emptying
- Thickness
- Aging of DF also affects drug release, especially with shellac coating
Eg : shellac coated tablets of salicylic acid stored for 2 years showed
a 60% decrease in the peak plasma level.
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14. SUSTAINED RELEASE PRODUCTS
• Drug release from such products is most unpredictable, the problems
ranging from dose dumping to unsatisfactory or no drug release at
all.
• With the development of newer innovation and technologies, it is
becoming increasingly reliable and the results reproducible with little
inter- subject variability.
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15. REFERENCE
1. Brahmankar D.M., Jaiswal S.B., First edition, “Absorption of Drugs”
Biopharmaceutics and Pharmacokinetics – A treatise, Vallabh
Prakashan, Delhi 1995.
2. Shargel L., Andrew B.C., Fourth edition “Physiologic factors related to
drug absorption” Applied Biopharmaceutics and Pharmacokinetics,
Prentice Hall International, INC., Stanford 1999.
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