exam revision Flashcards
Delayed Release
products coated and designed to pass through the stomach and only release within the INTESTINAL tract
Extended Release
Products designed to release medication in a controlled manner at a pre-determined rate, duration and location. Helps achieve and maintain optimum therapeutic blood levels of drug
What are the main advantages of Modified Drug release system?
- Less fluctuation in drug blood levels
- Frequency reduction in dosing
- enhanced convenience and compliance
- Reduction in ADRs
- Reduction in overall health cost
What are the disadvantages of Modified drug release?
- loss of flexibility
- dose dumping
- constraints on the types of drugs that suitable for the candidates
- limits the max period (approx. 12 hrs)
What are the 8 extended release technologies?
- Coated beads, granules, microspheres
- Multitablet system
- Microencapsulated drug
- Hydrophilic matrix systems
- Insoluble polymer matrix
- Complex Formation
- Ion Exchange resins
- Osmotic pumps
Delayed release of drug can be intentional till the intestines as it ensures:
- protection of drug from gastric fluids
- reduces gastric distress caused by the drug
- facilitating GI transit for drugs that are better absorbed from the intestines.
What are the 3 dependeds for enteric coating?
- pH
- time
- enzyme
What is repeat action? (Repeatabs)
Initial dose of drug is released immediately and a second dose follows later
What type of condition is repeat action used for?
- chronic conditions that require repeat doses
- Two layers may have one layer for immediate release with a second layer releasing drug later in an extended manner
How are targeted release drugs absorbed?
- colonic drug delivery which are only digested by colonic bacteria.
What are some clinical considerations to consider for modified drug release?
- should not use modified release products interchangeably with immediate release forms of the SAME drug
- patients who are stabilised on modified release product should not be changed as different extended release drugs can have different characteristics
- not to be crushed or chewed
- nasogastric tubes
What is transdermal drug delivery?
passage of therapeutic quantities of drug through the skin and into general circulation
What are the factors affecting percutaneous absorption?
- increase in drug concentration
- larger area of application
- drugs with a MW 100-800 with aqueous and lipid solubility
- has greater physiochemical attraction to the skin than vehicle
- Drugs generally penetrate better in their unionised nonpolar/lipophilic
- duration
- site
What are the advantages of Transdermal Drug Therapy?
- avoids GI drug absorption
- oral route is unsuitable as with vomiting and diarrhoea
- Avoids first-pass effect
- Non-invasive
- extended therapy with single application
- activity of drugs with shorter half-life
- terminated rapidly
- easily and rapidly identified
What are the main disadvantages of transdermal Drug Therapy?
- Relatively potent drugs are suitable due to natural limits of drug entry imposed via skin’s permeability
- Contact dermatitis
How is bioavailability of transdermal drug maximised?
- pro-drugs
- chemical potential adjustment
- hydration
- ion pairs
- ultrasound
- iontophoresis
- electroporation
- Stratum corneum removal
- photomechanical wave
- needleless injection
- needle array
- liposomes
- penetration enhancers
What is the structure of transdermal patch?
- protective layer
- adhesive layer
- backing layer
Where is the drug mainly located in a transdermal patch?
- adhesive layer
- contains the loading dose and penetration enhancers.
What occurs in the matrix system?
separate matrix to increase drug content and control release.
What is rate-limiting membrane system?
- contains drug in a reservoir with release controlled through a semipermeable membrane
What are some clinical considerations for Transdermal patch?
- rotate locations
- site of application
- clean, dry skin
- sensitivity
- cutting the patch may destroy its integrity
What types of drugs can be delivered via Transdermal?
- testosterone
- anti-inflammatories
- promethazine
- veterinary applications
- oestradiol
- nicotine
What are the implantable drug delivery systems types?
- nonbiodegradable implants via diffusion
- biodegradable implants which release via surface or bulk degradation
- mini pumps
- stents
- bioresponsive
What are the advantages of implantable drug delivery?
- convenience
- compliance
- controlled release
- intermittent/bio-responsive release
- improved drug delivery
- flexibility
- commercial advantages
What are the disadvantages of Implantable Drug delivery?
- invasive
- termination
- danger of device failure
- possibility of adverse reactions
- biocompatibility issues
- commercial disadvantages
What are some adverse effects caused by implantable drug delivery?
- implants can cause short or long term toxicity and acute chronic inflammatory responses
Adverse effects can be caused by the following options:
- polymer formation due to chemical reactivity of end or side groups
- residual contaminants
- toxic degradation products
How is biocompatibility defined?
as the performance and response of the host toward an implanted material.
What surrounds the reservoir device drug?
Rate-controlling polymer membrane that can be non-porous or microporous.
How is solvent loading achieved?
- immersing the device in solvent which an be done under pressure
- solvent selected affects drug permeability
What is the matrix-type implant drug distrubuted?
throughout a polymeric matrix
The total payload of a drug determines drug’s physical state in a polymer through what?
- Dissolved: low payload and drug is soluble
- Dispersed: present above the saturation level and additional drug exists as dispersed particles
- Porous
What are some examples of non-biodegradable polymeric impants?
- contraception (norplant)
- menopause
- ocular disease
- probuphine
