Podcast
Questions and Answers
What is a primary goal of developing sustained release drug delivery systems (SR DDS)?
What is a primary goal of developing sustained release drug delivery systems (SR DDS)?
Which of the following is a disadvantage of sustained/controlled release dosage forms?
Which of the following is a disadvantage of sustained/controlled release dosage forms?
What is the purpose of timed release drug delivery systems?
What is the purpose of timed release drug delivery systems?
Which of the following statements about zero-order release is true?
Which of the following statements about zero-order release is true?
Signup and view all the answers
What is a potential benefit of using sustained release dosage forms?
What is a potential benefit of using sustained release dosage forms?
Signup and view all the answers
What is the primary purpose of drug delivery systems?
What is the primary purpose of drug delivery systems?
Signup and view all the answers
Which of the following is a characteristic of conventional drug delivery systems?
Which of the following is a characteristic of conventional drug delivery systems?
Signup and view all the answers
What is one limitation of conventional drug delivery systems?
What is one limitation of conventional drug delivery systems?
Signup and view all the answers
Novel drug delivery systems are primarily researched to improve which aspect of drug action?
Novel drug delivery systems are primarily researched to improve which aspect of drug action?
Signup and view all the answers
Which term describes drug delivery at a predetermined rate for a specific time period?
Which term describes drug delivery at a predetermined rate for a specific time period?
Signup and view all the answers
Sustained drug delivery aims to achieve which of the following?
Sustained drug delivery aims to achieve which of the following?
Signup and view all the answers
What does targeted drug delivery primarily focus on?
What does targeted drug delivery primarily focus on?
Signup and view all the answers
Which of the following is NOT a type of novel drug delivery system?
Which of the following is NOT a type of novel drug delivery system?
Signup and view all the answers
What equation is used to calculate the rate of drug released (dm/dt)?
What equation is used to calculate the rate of drug released (dm/dt)?
Signup and view all the answers
What is a potential risk associated with reservoir devices if the membrane ruptures?
What is a potential risk associated with reservoir devices if the membrane ruptures?
Signup and view all the answers
Which characteristic does NOT influence the rate of drug release in reservoir devices?
Which characteristic does NOT influence the rate of drug release in reservoir devices?
Signup and view all the answers
What is true about matrix devices in drug delivery systems?
What is true about matrix devices in drug delivery systems?
Signup and view all the answers
What factors determine the rate of drug release from a matrix device?
What factors determine the rate of drug release from a matrix device?
Signup and view all the answers
Which of the following is an advantage of using a reservoir type drug delivery system?
Which of the following is an advantage of using a reservoir type drug delivery system?
Signup and view all the answers
What are commonly used polymers in reservoir devices?
What are commonly used polymers in reservoir devices?
Signup and view all the answers
Which statement accurately describes drug release in matrix devices?
Which statement accurately describes drug release in matrix devices?
Signup and view all the answers
What is a potential drawback of fracture in drug implantation systems?
What is a potential drawback of fracture in drug implantation systems?
Signup and view all the answers
What environmental condition prompts swelling-controlled release systems to expand?
What environmental condition prompts swelling-controlled release systems to expand?
Signup and view all the answers
What advantage does hydroxypropyl methylcellulose (HPMC) provide in drug release formulations?
What advantage does hydroxypropyl methylcellulose (HPMC) provide in drug release formulations?
Signup and view all the answers
Which of the following combinations may delay drug release rates when using HPMC?
Which of the following combinations may delay drug release rates when using HPMC?
Signup and view all the answers
What is a critical function of swelling in swelling-controlled drug release systems?
What is a critical function of swelling in swelling-controlled drug release systems?
Signup and view all the answers
What is a requirement for removing implanted drug delivery systems?
What is a requirement for removing implanted drug delivery systems?
Signup and view all the answers
What characteristic of HPMC enables customization of drug release profiles?
What characteristic of HPMC enables customization of drug release profiles?
Signup and view all the answers
When considering drug stability in delivery systems, what is an essential factor?
When considering drug stability in delivery systems, what is an essential factor?
Signup and view all the answers
What is a major advantage of erodible systems regarding polymer removal?
What is a major advantage of erodible systems regarding polymer removal?
Signup and view all the answers
How does hydrolysis contribute to bulk erosion in polymers?
How does hydrolysis contribute to bulk erosion in polymers?
Signup and view all the answers
Which of the following factors does NOT affect the degradation of polymers?
Which of the following factors does NOT affect the degradation of polymers?
Signup and view all the answers
What characteristic is common among synthetic biodegradable polymers utilized for drug delivery?
What characteristic is common among synthetic biodegradable polymers utilized for drug delivery?
Signup and view all the answers
Which process occurs during surface erosion of polymers?
Which process occurs during surface erosion of polymers?
Signup and view all the answers
Which polymer is NOT mentioned as a common synthetic biodegradable polymer for drug delivery?
Which polymer is NOT mentioned as a common synthetic biodegradable polymer for drug delivery?
Signup and view all the answers
What is a key reason for the use of polyesters in drug delivery systems?
What is a key reason for the use of polyesters in drug delivery systems?
Signup and view all the answers
Which of the following drugs is not listed as being delivered using polyester-based systems?
Which of the following drugs is not listed as being delivered using polyester-based systems?
Signup and view all the answers
Study Notes
Introduction
- Drug delivery systems encapsulate drugs in nanoparticles such as micelles, liposomes, nanocapsules, nanospheres, and others.
- This encapsulation improves therapeutic index and reduces adverse side effects.
Classification of drug delivery systems
- Drug delivery systems (DDSs) are divided into two main types:
- Conventional DDSs / immediate release formulations
- Novel drug delivery systems (NDDS)
Conventional DDSs
- These systems provide rapid onset of action for some drugs like analgesics, antipyretics, and vasodilators.
- Includes simple methods like oral, topical, inhaled, or injection.
Limitations of conventional DDSs
- Rapid drug elimination leading to frequent dosing
- Fluctuations in plasma drug levels resulting in adverse effects
- Inability to target specific sites in the body
Novel Drug Delivery Systems (NDDS)
- Focus on controlling pharmacokinetics (ADME), pharmacodynamics, non-specific toxicity, immunogenicity, and drug efficacy.
- Address drug delivery complications that conventional systems cannot minimize.
- Often called "controlled DDS" and use advanced techniques and new dosage forms.
Terminology
- Rate controlled delivery: Delivers drugs at a predetermined rate systemically or locally for a specified period.
- Sustained/prolonged/extended drug delivery: Releases drugs slowly and provides a continuous supply over a prolonged period.
- Targeted drug delivery: Delivers drugs to specific sites in the body.
- Zero-order release: Drug release does not vary with time, maintaining a relatively constant level in the body for longer periods.
- Timed (delayed) release DDS: Releases drugs after a lag time of 4-5 hours.
- Enteric coated dosage: Designed to protect the drug in the stomach and release it in the colon.
Rationale for Developing SR DDS
- Extends the duration of drug action.
- Reduces dosing frequency.
- Minimizes plasma level fluctuations.
- Improves drug utilization.
- Minimizes adverse effects.
- Improves patient compliance.
Conventional vs Controlled Release DDS
-
Conventional Release:
- Frequent dosing (rapid elimination)
- Fluctuation in plasma levels
- Limited targeting
-
Controlled Release:
- Reduced dosing frequency
- Stable plasma levels
- Targeted delivery
Advantages of Sustained/Controlled Release Dosage Forms
- Reduced drug administration frequency.
- Reduced plasma level fluctuations.
- Avoidance of night-time dosing.
- Increased patient compliance.
- More uniform effect.
Disadvantages of Sustained/Controlled Release Dosage Forms
- Unpredictable or poor in vitro/in vivo correlation.
- Reduced potential for dose adjustment.
- Possibility of dose dumping (sudden release of a large amount of drug).
- Delay in onset of drug action.
- Poor systemic availability in general.
Fick's first law of diffusion
- Calculates the rate of drug released (dm/dt).
- Formula: dm/dt = ADK ΔC/L
- A = Area
- D = Diffusion coefficient
- K = Partition coefficient
- L = Diffusion path length
- ΔC = Concentration difference across the membrane.
Diffusion-Controlled Systems
-
Reservoir device: Drug is contained in a core reservoir covered by a thin polymeric membrane.
- Release is by diffusion through the membrane.
- Rate is governed by membrane thickness, porosity, and drug characteristics.
- Risk of dose dumping if the membrane ruptures.
- Difficult for high molecular weight compounds.
-
Matrix device: Drug is dispersed throughout a polymer matrix.
- Release depends on the rate of drug diffusion.
- Easier to produce than reservoir devices.
- Can deliver high molecular weight compounds.
Difference between Reservoir and Matrix Systems
-
Reservoir:
- Advantages: Zero-order delivery, variable release rates.
- Disadvantages: Dose dumping risk, removal required for implants, difficult for high molecular weight.
-
Matrix:
- Advantages: Easier to produce, high molecular weight delivery.
- Disadvantages: No zero-order release, removal required for implants, potential toxicity if system fails.
Swelling-Controlled Systems
- Dry system swells when it absorbs water or body fluids, increasing the solvent content within the formulation and enabling drug diffusion.
- Common polymers used: hydroxypropyl methylcellulose (HPMC) and methylcellulose (MC).
- Drug release is controlled by the rate of polymer matrix swelling.
- HPMC is a key polymer for hydrophilic matrices due to fast, uniform gel formation, providing a diffusional barrier to control release.
Erodible Systems
- Two major advantages:
- Polymers do not need to be removed from the body after drug delivery.
- Drugs do not need to be water-soluble.
Biodegradable Polymers for Drug Delivery
- Two types of biodegradation:
- Bulk erosion: Degradation occurs throughout the polymer by hydrolysis, breaking down large polymers into smaller biocompatible compounds.
- Surface erosion: Degradation occurs only at the polymer surface.
- Factors affecting degradation:
- Chemical structure and composition
- Molecular weight
- Concentration
- Hydrophilicity/hydrophobicity
- Carrier size, shape, and porosity
- Additives
- Microenvironmental pH
- Method of preparation
- Sterilization
- Examples of successfully used biodegradable polymers:
- Polylactic acid and polyglycolic acid
- Polycaprolactone (polyesters: aliphatic homo-polymer)
- Common characteristics of biodegradable polymers:
- Stability with drug molecules
- Biocompatible and biodegradable
- Ease of large-scale manufacture
- Amenable to sterilization
- Flexibility for multiple release profiles
Polyesters in Drug Delivery
- Polyesters and copolymers have been tested for injectable drug delivery.
- Applications: implants, nanoparticles, and microspheres for delivering various drugs (narcotic antagonists, contraceptives, local anesthetics, cytotoxics, and antimalarial agents).
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
Explore the fundamentals of drug delivery systems, focusing on conventional and novel drug delivery methods. This quiz covers the mechanisms, limitations, and advancements in encapsulating drugs to enhance therapeutic effects. Ideal for students and professionals in pharmacology and related fields.