Questions and Answers
Where does the absorption of Ferrous sulfate primarily occur?
Gastric floating is used to decrease the retention time of drugs in the gastrointestinal tract.
False
Name an example of a drug that is extensively metabolized in the intestine.
Aloprenolol
The lower limit of solubility for a sustained release system is _____ mg/mL.
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Match the following terms with their correct descriptions:
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Which of the following drug properties can limit the choice of mechanism for sustained release systems?
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Drug formulations with larger dose sizes can be effectively created as sustained release products.
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What is a common formulation approach for enzymes susceptible drugs?
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Compounds with very low solubility (_____ mg/mL) are inherently sustained.
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Which factor primarily determines the retention of a compound in the body?
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Study Notes
Novel Drug Delivery Systems
- Transition from traditional pill forms to programmable, smart drug delivery systems.
- Aim to enhance drug safety, efficacy, and patient compliance through controlled plasma drug levels.
Rationale for Modified Release Systems
- Conventional dosage forms cause rapid drug release, requiring frequent administration and leading to fluctuating plasma levels.
- Modified release systems allow for therapeutic levels with reduced dosing frequency.
- These systems ensure precise positioning within the body over time for improved efficacy and safety.
Classification of Modified Release Systems
- Delayed Release: Releases medication after a specified delay.
- Extended Release: Gradually releases drugs over time.
- Orally Disintegrating Tablets (ODT): Quickly dissolve in the mouth.
- Sustained Release (Controlled Release): Maintains drug concentration over an extended period.
- Site Specific and Receptor Release: Targets specific organs/tissues or receptors for enhanced therapeutic effects.
- Repeat Action: Contains two doses for immediate and delayed release.
Advantages of Modified Release Dosage Forms
- Improves patient compliance by reducing dosing frequency.
- Enhances drug utilization and minimizes side effects.
- Supports chronic condition treatment by controlling drug levels.
- Increases bioavailability for certain drugs.
- Economical compared to multiple conventional doses.
Limitations of Modified Release Systems
- Inappropriate for drugs with a narrow therapeutic index and irregular absorption.
- Not suitable for drugs with long half-lives or high required doses.
- The dose cannot be subdivided, unlike conventional forms.
Diffusion Theory
- Molecular transfer occurs from a region of high concentration to low concentration, termed diffusion.
- Driving force for diffusion is the concentration gradient across the diffusional barrier.
- Fick’s first law describes diffusion rate, where flux (J) is proportional to the concentration gradient (dC/dx).
Types of Diffusion Sustained Systems
- Porous Membrane Controlled System: Utilizes polymer membranes to regulate drug release via micro-pores.
- Porous Matrix Controlled System: Controls drug release through a matrix design.
Evaluation of Drug Release
- Drug release is assessed through in vitro and in vivo studies.
- In Vitro Studies: Measure the dissolution rate of drugs under specified conditions using various apparatus.
- Tests require that a minimum of 70% of the active ingredient is released within specified time intervals.
Sensitivity and Data Analysis
- Factors affecting drug release include composition of dissolution media and agitation rate.
- Key considerations involve evaluating potential dose dumping and the uniformity of the release profile.
Model Dependent Methods
- Release kinetics can follow zero order or first order kinetics, applicable to different drug absorption sites.
- Strategies like gastric floating or bioadhesion can enhance sustained release and absorption.
Physico-Chemical Factors
- Large dose sizes limit the use of sustained release formulations.
- Ionization and solubility play critical roles in drug formulation: low solubility limits options for sustained release mechanisms.
- High partition coefficients ensure longer retention in the body due to lipid solubility.
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Description
Learn about advanced drug delivery systems that have evolved from simple pills to programmable, time-controlled smart systems. Understand the objectives and benefits of modified release systems.
