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Questions and Answers
What is a primary purpose of certain drug formulations?
What is a primary purpose of certain drug formulations?
Which of the following refers to the controlled release of medication?
Which of the following refers to the controlled release of medication?
What is the advantage of a sustained release dosage form?
What is the advantage of a sustained release dosage form?
How does sustained release differ from conventional dosing?
How does sustained release differ from conventional dosing?
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What describes a toxic level in medication usage?
What describes a toxic level in medication usage?
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What is the primary goal of a modified release drug delivery system?
What is the primary goal of a modified release drug delivery system?
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What is a major drawback of using conventional dosage forms?
What is a major drawback of using conventional dosage forms?
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How does increased frequency of medication administration impact patient compliance?
How does increased frequency of medication administration impact patient compliance?
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Why is maintaining steady-state drug levels particularly significant for drugs with narrow therapeutic indices?
Why is maintaining steady-state drug levels particularly significant for drugs with narrow therapeutic indices?
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What has been a result of the challenges faced by conventional drug therapies?
What has been a result of the challenges faced by conventional drug therapies?
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One of the key pharmaceutical aims is to optimize what aspect of drug absorption?
One of the key pharmaceutical aims is to optimize what aspect of drug absorption?
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What can excessively low trough levels of a drug lead to?
What can excessively low trough levels of a drug lead to?
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What aspect of modified release systems resolves poor patient compliance?
What aspect of modified release systems resolves poor patient compliance?
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What is one disadvantage of developing new drugs with long half-lives?
What is one disadvantage of developing new drugs with long half-lives?
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What does a modified release product initially provide?
What does a modified release product initially provide?
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What is one characteristic of controlled delivery systems?
What is one characteristic of controlled delivery systems?
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What happens after the initial priming dose in a modified release product?
What happens after the initial priming dose in a modified release product?
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Which terminology is not interchangeable with controlled release according to the USP?
Which terminology is not interchangeable with controlled release according to the USP?
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What is a typical drug blood level versus time profile characterized by in multiple-dose therapy?
What is a typical drug blood level versus time profile characterized by in multiple-dose therapy?
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Why is there increased interest in controlled delivery systems?
Why is there increased interest in controlled delivery systems?
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What is the primary goal of a maintenance dose in modified release products?
What is the primary goal of a maintenance dose in modified release products?
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What is meant by modified release in pharmacology?
What is meant by modified release in pharmacology?
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Which of the following is NOT a principle of obtaining prolonged-action preparations?
Which of the following is NOT a principle of obtaining prolonged-action preparations?
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What role do vasoconstrictors play in prolonging the action of local anesthetics?
What role do vasoconstrictors play in prolonging the action of local anesthetics?
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Which of the following methods is used to achieve prolonged drug release via binding?
Which of the following methods is used to achieve prolonged drug release via binding?
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How can coating a drug affect its release rate?
How can coating a drug affect its release rate?
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What is an example of a technological process for formulating dosage forms?
What is an example of a technological process for formulating dosage forms?
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Which of the following definitions applies to ‘controlled release’ dosage forms?
Which of the following definitions applies to ‘controlled release’ dosage forms?
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Why is enzyme induction utilized in prolonged drug action?
Why is enzyme induction utilized in prolonged drug action?
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What is the primary characteristic of an extended-release dosage form?
What is the primary characteristic of an extended-release dosage form?
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What defines a controlled-release dosage form?
What defines a controlled-release dosage form?
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What is the purpose of a sustained-release drug product?
What is the purpose of a sustained-release drug product?
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What is a characteristic of delayed-release systems?
What is a characteristic of delayed-release systems?
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How does a long-acting dosage form prolong biological half-life?
How does a long-acting dosage form prolong biological half-life?
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What is the primary goal of targeted-release dosage forms?
What is the primary goal of targeted-release dosage forms?
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What defines the role of an enteric-coated tablet?
What defines the role of an enteric-coated tablet?
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What is a key feature of the dissolution profile for an extended-release dosage form?
What is a key feature of the dissolution profile for an extended-release dosage form?
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Study Notes
Modified Release Drug Delivery System
- Ideal drug delivery systems provide therapeutic concentrations at the site of action for the desired duration of treatment.
- Maintaining a constant "steady state" plasma concentration is achieved through repetitive administration of conventional dosage forms.
- Conventional dosage forms aim for maximal physical/chemical stability and bioavailability, optimized for drug absorption rate and extent.
Problems with Conventional Dosage Forms
- Poor patient compliance, particularly with drugs having short biological half-lives necessitating frequent dosing (2-4 times a day).
- Increased frequency of administration increases the risk of missed doses.
- Significant fluctuations in peak and trough plasma drug levels upon repeated administration can lead to undesirable side effects (high peaks, low troughs).
Modified Release Drug Delivery Systems
- Overcome problems associated with conventional dosage forms by controlling drug release rate.
- Provide a sustained/prolonged therapeutic concentration.
- Examples of terms used interchangeably include controlled release, sustained release, and prolonged release.
- Modified-release dosage forms continuously release drugs at controlled rates to create a prolonged therapeutic effect following a single dose.
Mechanisms for Modified Release Preparations
- Using pharmacokinetic phase:
- Prolonging absorption, metabolism, or excretion by altering drug absorption, metabolism, or excretion
- Utilizing chemical reactions:
- Modify drug chemical structure into prodrugs
- Alter drug solubility, binding to proteins, and partition coefficient
- Utilizing technological processes:
- Change solvent types
- Add viscosity enhancers
- Utilize insoluble adsorbents for drug absorption
- Encapsulate drug in multilayer structures
- Methods for modified release:
- Coating, film forming, embedding in matrices, osmotic pressure application
Dissolution Systems
- Drugs with inherently low aqueous solubility naturally exhibit sustained release characteristics.
- Dissolution rate in gastrointestinal medium can be controlled for highly soluble drugs
- Key steps in dissolution:
- Initial detachment from solid structure to liquid interface
- Drug molecule diffusion into bulk liquid medium
Diffusion Systems
- Diffusion is the spontaneous transfer of molecules to achieve chemical potential equilibrium.
- Controlled diffusion release through inert polymer barriers.
- Two types of diffusion systems:
- Reservoir systems: A drug core encapsulated in a polymeric membrane barrier.
- Matrix systems: Uniformly dispersed drug within an insoluble polymer matrix.
Erosion Systems
- Erosion of the polymer controls drug release.
- Bulk release results from rapid polymer degradation while surface release comes from the boundaries.
- Erosion is dependent on the polymer dissolution and diffusion rates.
Swelling Systems
- Drug is dispersed in polymer, instead of using impermeable polymers, swellable polymers are used.
- Swelling controlled matrices use a combination of diffusion and dissolution.
- Swelling controlled systems are especially effective for drugs with narrow therapeutic indices.
Ion-exchange Resin Systems
- Water-insoluble crosslinked polymers are utilized, with charged ion-exchange groups.
- Drug release is controlled by interaction between drug and the resin, along with factors like ionic environment and diffusion path length.
Osmotic Pump Systems
- Osmotic pressure differences across a semi-permeable membrane drive drug release at a constant rate (zero-order release).
- The system has an osmotic core containing a drug and an osmotically active agent or salt coated with a semi-permeable membrane.
- Water uptake through the membrane creates hydrostatic pressure that expels the drug solution from the dosage form.
- Two types:*
- Elementary osmotic pumps (EOPs):
- Oral osmotic pumps (OROS):
Hydrodynamic Pressure Controlled Systems
- Drug release is triggered by hydrodynamic pressure created by swelling.
- A hydrophilic gum layer swells, creating a pressure difference to expel the drug.
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Description
Explore the benefits and challenges of modified release drug delivery systems compared to conventional dosage forms. This quiz covers key concepts like maintaining therapeutic concentrations and improving patient compliance. Delve into how these systems aim to provide controlled drug release and minimize side effects.
