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Questions and Answers
What is the primary purpose of coating drug particles in reservoir dissolution controlled formulations?
What is the primary purpose of coating drug particles in reservoir dissolution controlled formulations?
According to the Noyes-Whitney equation, which factor does NOT directly influence the dissolution rate of a drug?
According to the Noyes-Whitney equation, which factor does NOT directly influence the dissolution rate of a drug?
How does microencapsulation impact the drug release process?
How does microencapsulation impact the drug release process?
Which of the following accurately describes microencapsulated particles?
Which of the following accurately describes microencapsulated particles?
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What effect does the thickness of the coating have on drug release in reservoir dissolution formulations?
What effect does the thickness of the coating have on drug release in reservoir dissolution formulations?
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What dual mechanism does Ambien CR utilize for drug release?
What dual mechanism does Ambien CR utilize for drug release?
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What role does HPMC polymer play in Ambien CR?
What role does HPMC polymer play in Ambien CR?
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Which technique is NOT used to prepare drug-charged ion exchange resins?
Which technique is NOT used to prepare drug-charged ion exchange resins?
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What is the primary characteristic of the drug release from ion exchange resins?
What is the primary characteristic of the drug release from ion exchange resins?
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Why are ion exchange resins not suitable for skin applications?
Why are ion exchange resins not suitable for skin applications?
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In which part of the drug-exchange process do drug ions diffuse out of the resin?
In which part of the drug-exchange process do drug ions diffuse out of the resin?
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What happens to the drug when the ion concentration changes in the solution?
What happens to the drug when the ion concentration changes in the solution?
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Which polymer is commonly used as a coating material for ion exchange resins?
Which polymer is commonly used as a coating material for ion exchange resins?
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What distinguishes CPOP from traditional osmotic delivery systems?
What distinguishes CPOP from traditional osmotic delivery systems?
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Which feature of PPOP aids in the controlled release of the drug?
Which feature of PPOP aids in the controlled release of the drug?
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What is the characteristic of the swelling agents used in osmotic tablets?
What is the characteristic of the swelling agents used in osmotic tablets?
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What are enteric polymers known for in terms of solubility?
What are enteric polymers known for in terms of solubility?
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Which statement about drug release in EOP and CPOP is correct?
Which statement about drug release in EOP and CPOP is correct?
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Which of the following polymers is NOT identified as an enteric polymer?
Which of the following polymers is NOT identified as an enteric polymer?
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What does the push-stick osmotic pump (PSOP) technology combine?
What does the push-stick osmotic pump (PSOP) technology combine?
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What distinguishes controlled release tablets from sustained release tablets?
What distinguishes controlled release tablets from sustained release tablets?
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In terms of drug solubility, which drugs are poor candidates for osmotic delivery systems?
In terms of drug solubility, which drugs are poor candidates for osmotic delivery systems?
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What is the benefit of using enteric coated tablets?
What is the benefit of using enteric coated tablets?
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What is the role of the middle push layer in a sandwiched osmotic tablet (SOTS)?
What is the role of the middle push layer in a sandwiched osmotic tablet (SOTS)?
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Which term is synonymous with controlled release?
Which term is synonymous with controlled release?
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What type of polymers are typically used as swelling agents in osmotic tablets?
What type of polymers are typically used as swelling agents in osmotic tablets?
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What characterizes the drug release in controlled release dosage forms?
What characterizes the drug release in controlled release dosage forms?
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In what way does sustained release differ from controlled release?
In what way does sustained release differ from controlled release?
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Why are controlled release formulations considered beneficial?
Why are controlled release formulations considered beneficial?
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What is the main purpose of incorporating sodium bicarbonate and calcium carbonate in gastroretentive systems?
What is the main purpose of incorporating sodium bicarbonate and calcium carbonate in gastroretentive systems?
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Which polymeric excipients are used as rate-controlling agents in the swellable triple layer system?
Which polymeric excipients are used as rate-controlling agents in the swellable triple layer system?
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What characteristic does the swellable floating system provide when it comes into contact with gastric fluids?
What characteristic does the swellable floating system provide when it comes into contact with gastric fluids?
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Which of the following products utilizes HBS floating technology?
Which of the following products utilizes HBS floating technology?
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In the context of gastroretentive systems, what is the primary benefit of prolonged gastric residence time?
In the context of gastroretentive systems, what is the primary benefit of prolonged gastric residence time?
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Which active ingredient is NOT part of the triple drug regimen for Helicobacter pylori–associated peptic ulcers?
Which active ingredient is NOT part of the triple drug regimen for Helicobacter pylori–associated peptic ulcers?
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What type of drug release is associated with the hydrocolloid-based gastroretentive systems?
What type of drug release is associated with the hydrocolloid-based gastroretentive systems?
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What is a significant logistical challenge in treating diseases like malaria, TB, and HIV in rural populations?
What is a significant logistical challenge in treating diseases like malaria, TB, and HIV in rural populations?
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Study Notes
Enteric Polymers
- Enteric polymers are insoluble at pH 6 or below (stomach), but above pH 6 (intestine), they ionize and become soluble.
- Examples of enteric polymers include:
- Cellulose acetate phthalate (CAP)
- Hydroxypropyl methyl cellulose phthalate (HPMCP)
- Hydroxypropyl methyl cellulose acetate-succinate (HPMCAS)
- Polyvinyl acetate phthalate (PVAP)
- Methacrylic acid copolymers (Eudragit ® NE 30 D, L100, S100)
- Tablets coated with enteric polymers are called Enteric Coated Tablets.
Controlled Release Tablets
- Controlled release tablets are designed to release medication at a specific rate and time for therapeutic effect.
- Controlled release, prolonged release, sustained or slow release, and long-acting, are synonymous with extended release.
- Controlled drug delivery systems release the drug at a predetermined rate for a set time, aiming for zero-order release (consistent rate, regardless of concentration).
Sustained Release Tablets
- A sustained-release dosage form releases an initial dose for immediate effect and then releases the remaining portion slowly to maintain therapeutic levels for an extended duration.
- Sustained release does not necessarily mean controlled release.
Controlled Release vs. Immediate Release
- MEC (minimum effective concentration): The lowest concentration of medication needed for a therapeutic effect.
- MTC (minimum toxic concentration): The lowest concentration of medication that causes toxic effects.
- Therapeutic Window: The range of drug concentrations between MEC and MTC, where the drug is effective and safe.
- Half-life: The time taken for the body to eliminate half of the drug from the bloodstream.
Why Controlled Release?
- Controlled release formulations offer advantages over immediate release formulations, such as:
- Reduced dosing frequency
- Improved patient compliance
- More consistent therapeutic levels
- Reduced side effects
Drug Dissolution
-
Noyes-Whitney equation describes the rate of drug dissolution:
- dm/dt: Solute dissolution rate (kg/s)
- m: Mass of dissolved material (kg)
- t: Time (s)
- A: Surface area of the solute particle (m2)
- d: Thickness of the concentration gradient (m)
- D: Diffusion coefficient (m/s), related to solvent viscosity
- Cs: Particle surface concentration (saturation) (kg or moles/L)
- Cb: Concentration in the bulk solution (kg or moles/L)
Reservoir Dissolution Controlled Formulation: Coating
- Individual drug particles or granules are coated with a slow-dissolving material.
- The coated particles are compressed into tablets or placed in capsules.
- The rate of drug release is controlled by the coating.
- Varying the coating thickness and composition controls the release rate.
Reservoir Dissolution Controlled Formulation: Microencapsulation
- Microencapsulation involves encapsulating solid, liquid, or gas materials into microparticles (1-1000 μm) with a core-shell structure.
- The coating material can be natural or synthetic polymers, depending on the desired release characteristics.
Ion Exchange Resins (IER)
- IERs are water-insoluble materials with charged groups on the resin chain.
- Drug-charged resins are prepared using batch or column techniques.
- Drug release is dependent on the ionic environment of the resin, making it less susceptible to pH or enzyme content.
- IERs are not suitable for dermal or parenteral delivery.
Osmotic Controlled Delivery Systems
- Push-Pull Osmotic System (PPOP): A multilayer system with a push layer that expands on contact with water, pushing the drug suspension through an orifice for controlled release.
- Push-Stick Osmotic System (PSOP): A modified PPOP incorporating immediate and sustained drug release phases, suitable for poorly or highly water-soluble drugs.
- Sandwiched Osmotic Tablet (SOTS): A tablet core with a push layer and two drug layers, coated with a semipermeable membrane.
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Factors affecting drug release from osmotic pumps:
- Drug solubility: Highly or poorly water-soluble drugs are not ideal for osmotic delivery.
- CO2 generation: CO2 can cause swelling, leading to floating ability independent of pH and viscosity.
Gastroretentive Systems
- Swellable Triple Layer System: Contains a core layer for controlled delivery, an outer layer for instant release, and a gas-generating layer for buoyancy.
- Swellable Floating System: Contains hydrophilic colloids that form a gelatinous mass on the tablet surface, creating a water-impermeable barrier and buoyancy.
Marketed Gastroretentive Products
- Madopar HBS: Levodopa and benserzide, HBS floating technology.
- Valrease: Diazepam, HBS floating technology.
- Liquid Gaviscon: Alginic acid and sodium bicarbonate, HBS floating technology.
- Topalkan: Aluminum magnesium antacid, HBS floating technology.
- Almagate: Antacid, HBS floating technology.
- Glumetza: Metformin, size-increasing technology.
- Proquin: Ciprofloxacin, size-increasing technology.
Ultra Long-Acting Oral Systems
- Ultra-long-acting oral systems are important for treating chronic diseases (malaria, TB, HIV).
- They aim to improve patient adherence and reduce logistical challenges in reaching rural populations.
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Description
Test your knowledge on enteric polymers, controlled release tablets, and sustained release tablets in this quiz. Explore key concepts surrounding drug delivery systems and their formulations. Perfect for students of pharmaceutical sciences or related fields.