This document discusses implantable drug delivery systems. Implants provide controlled delivery of drugs over long periods of time at the site of implantation. There are biodegradable and non-biodegradable implants. Implants can be classified based on their release mechanism, such as membrane permeation controlled, matrix diffusion controlled, or activation modulated systems. Implants offer benefits like continuous drug delivery and avoidance of peak concentrations but have disadvantages like requiring surgery and host reactions. Common applications of implants include cancer treatment, contraception, and ocular diseases.
Mucoadhesive drug delivery system interact with the mucus layer covering the mucosal epithelial surface, & mucin molecules & increase the residence time of the dosage form at the site of the absorption.
Mucoadhesive drug delivery system is a part of controlled delivery system.
Since the early 1980,the concept of Mucoadhesion has gained considerable interest in pharmaceutical technology.
combine mucoadhesive with enzyme inhibitory & penetration enhancer properties & improve the patient complaince.
MDDS have been devloped for buccal ,nasal,rectal &vaginal routes for both systemic & local effects.
Hydrophilic high mol. wt. such as peptides that cannot be administered & poor absorption ,then MDDS is best choice.
Mucoadhesiveinner layers called mucosa inner epithelial cell lining is covered with viscoelasticfluid
Composed of water and mucin.
Thickness varies from 40 μm to 300 μm
General composition of mucus
Water…………………………………..95%
Glycoproteinsand lipids……………..0.5-5%
Mineral salts……………………………1%
Free proteins…………………………..0.5-1%
The mechanism responsible in the formation of mucoadhesive bond
Step 1 : Wetting and swelling of the polymer(contact stage)
Step 2 : Interpenetration between the polymer chains and the mucosal membrane
Step 3 : Formation of bonds between the entangled chains (both known as consolidation stage)
Electronic theory
Wetting theory
Adsorption theory
Diffusion theory
Fracture theory
Advantages over other controlled oral controlled release systems by virtue of prolongation of residence of drug in GIT.
Targeting & localization of the dosage form at a specific site
-Painless administration.
-Low enzymatic activity & avoid of first pass metabolism
If MDDS are adhere too tightlgy because it is undesirable to exert too much force to remove the formulation after use,otherwise the mucosa could be injured.
-Some patient suffers unpleasent feeling.
-Unfortunately ,the lack of standardized techniques often leads to unclear results.
-costly drug delivery system
Gastro retentive drug delivery system (GRDDS)Shweta Nehate
Oral route is the most acceptable route for drug administration. Apart from conventional dosage forms several other forms were developed in order to enhance the drug delivery for prolonged time period and for delivering drug to a particular target site. Gastro-retentive drug delivery system (GRDDS) has gainned immense popularity in the field of oral drug delivery recently. it is a widely employed approach to retain the dosage form in the stomach for an extended period of time and release the drug slowly that can address many challenges associated with conventional oral delivery, including poor bioavailability. different innovative approaches are being applied to fabricate GRDDS. Gastroretentive drug delivery is an approach to prolong gastric residence time, there by targeting site-specific drugs release in the upper gastrointestinal tract (GIT) for local or systemic effects. It is obtained by retaining dosage form into stomach and by releasing the in controlled manner.
Mucoadhesive drug delivery system interact with the mucus layer covering the mucosal epithelial surface, & mucin molecules & increase the residence time of the dosage form at the site of the absorption.
Mucoadhesive drug delivery system is a part of controlled delivery system.
Since the early 1980,the concept of Mucoadhesion has gained considerable interest in pharmaceutical technology.
combine mucoadhesive with enzyme inhibitory & penetration enhancer properties & improve the patient complaince.
MDDS have been devloped for buccal ,nasal,rectal &vaginal routes for both systemic & local effects.
Hydrophilic high mol. wt. such as peptides that cannot be administered & poor absorption ,then MDDS is best choice.
Mucoadhesiveinner layers called mucosa inner epithelial cell lining is covered with viscoelasticfluid
Composed of water and mucin.
Thickness varies from 40 μm to 300 μm
General composition of mucus
Water…………………………………..95%
Glycoproteinsand lipids……………..0.5-5%
Mineral salts……………………………1%
Free proteins…………………………..0.5-1%
The mechanism responsible in the formation of mucoadhesive bond
Step 1 : Wetting and swelling of the polymer(contact stage)
Step 2 : Interpenetration between the polymer chains and the mucosal membrane
Step 3 : Formation of bonds between the entangled chains (both known as consolidation stage)
Electronic theory
Wetting theory
Adsorption theory
Diffusion theory
Fracture theory
Advantages over other controlled oral controlled release systems by virtue of prolongation of residence of drug in GIT.
Targeting & localization of the dosage form at a specific site
-Painless administration.
-Low enzymatic activity & avoid of first pass metabolism
If MDDS are adhere too tightlgy because it is undesirable to exert too much force to remove the formulation after use,otherwise the mucosa could be injured.
-Some patient suffers unpleasent feeling.
-Unfortunately ,the lack of standardized techniques often leads to unclear results.
-costly drug delivery system
Gastro retentive drug delivery system (GRDDS)Shweta Nehate
Oral route is the most acceptable route for drug administration. Apart from conventional dosage forms several other forms were developed in order to enhance the drug delivery for prolonged time period and for delivering drug to a particular target site. Gastro-retentive drug delivery system (GRDDS) has gainned immense popularity in the field of oral drug delivery recently. it is a widely employed approach to retain the dosage form in the stomach for an extended period of time and release the drug slowly that can address many challenges associated with conventional oral delivery, including poor bioavailability. different innovative approaches are being applied to fabricate GRDDS. Gastroretentive drug delivery is an approach to prolong gastric residence time, there by targeting site-specific drugs release in the upper gastrointestinal tract (GIT) for local or systemic effects. It is obtained by retaining dosage form into stomach and by releasing the in controlled manner.
Video Lecture is available at https://www.youtube.com/watch?v=DXu_CLgB4q0
Introduction, terminology/definitions and rationale, advantages, disadvantages, selection of drug candidates. Approaches to design-controlled release formulations based on diffusion, dissolution and ion exchange principles. Physicochemical and
biological properties of drugs relevant to controlled release formulations.
Application Of Polymer In Controlled Release FormulationAnindya Jana
Polymers are becoming increasingly important in the field of drug delivery. The pharmaceutical applications of polymers range from their use as binders in tablets to viscosity and flow controlling agents in liquids, suspensions and emulsions. Polymers can be used as film coatings to disguise the unpleasant taste of a drug, to enhance drug stability and to modify drug release characteristics.
As a consequence, increasing attention has been focused on methods of giving drugs continually for a prolonged time periods and in a controlled fashion.
This technology now spans many fields and includes pharmaceutical, food and agricultural applications, pesticides, cosmetics, and household products.
Video Lecture is available at https://www.youtube.com/watch?v=DXu_CLgB4q0
Introduction, terminology/definitions and rationale, advantages, disadvantages, selection of drug candidates. Approaches to design-controlled release formulations based on diffusion, dissolution and ion exchange principles. Physicochemical and
biological properties of drugs relevant to controlled release formulations.
Application Of Polymer In Controlled Release FormulationAnindya Jana
Polymers are becoming increasingly important in the field of drug delivery. The pharmaceutical applications of polymers range from their use as binders in tablets to viscosity and flow controlling agents in liquids, suspensions and emulsions. Polymers can be used as film coatings to disguise the unpleasant taste of a drug, to enhance drug stability and to modify drug release characteristics.
As a consequence, increasing attention has been focused on methods of giving drugs continually for a prolonged time periods and in a controlled fashion.
This technology now spans many fields and includes pharmaceutical, food and agricultural applications, pesticides, cosmetics, and household products.
Implantable Drug Delivery Systems: Delivering Medication on Demand
Implantable drug delivery systems (IDDS) are miniature devices surgically placed under the skin or inside tissues to deliver a sustained and controlled release of medication directly to the target site. This targeted approach offers several advantages over traditional oral or injectable medications:
Benefits:
Improved treatment compliance: Eliminates the need for frequent dosing, improving adherence to treatment plans.
Enhanced efficacy: Delivers drugs directly to the site of action, maximizing their therapeutic effect.
Reduced side effects: Minimizes systemic exposure to the drug, potentially reducing unwanted side effects.
Controlled release: Offers precise control over the release rate and duration of medication delivery, optimizing treatment effectiveness.
Long-term therapy: Can provide continuous medication delivery for months or even years, ideal for chronic conditions.
Types of IDDS:
Biodegradable implants: Made from materials that naturally degrade over time, releasing the drug at a predetermined rate.
Non-biodegradable implants: Composed of materials that remain in the body after the drug is released, requiring surgical removal.
Reservoir implants: Contain a pre-filled reservoir of medication released through a controlled mechanism.
Pump implants: Use a micro-pump to deliver the medication at specific intervals or in response to external stimuli.
Applications:
Pain management: Chronic pain, post-surgical pain, arthritis
Hormonal therapy: Contraception, hormone replacement therapy
Cancer treatment: Localized chemotherapy, targeted drug delivery
Psychiatric disorders: Depression, schizophrenia
Neurological disorders: Parkinson's disease, epilepsy
Challenges and considerations:
Surgical implantation: Requires a minor surgical procedure, carrying associated risks and potential complications.
Cost: The devices and implantation procedure can be expensive.
Limited drug suitability: Not all medications are compatible with IDDS technology.
Device failure: Mechanical malfunctions or material degradation can occur over time.
Future of IDDS:
Advancements in materials science, miniaturization, and biocompatibility are paving the way for more sophisticated IDDS with:
Closed-loop systems: Sensors monitoring disease markers and adjusting drug release in real-time.
Multifunctional capabilities: Combining drug delivery with other functionalities like disease monitoring or biostimulation.
Personalized medicine: Tailored IDDS designed for individual patient needs and genetic profiles.
Implants are cylindrical, monolithic devices of millimeter or centimeter dimensions, implanted into the subcutaneous or intramuscular tissue by an minor surgical incision or injected through a large bore needle; and release the incorporated drug in a controlled manner, allowing the adjustment of release rates over extended periods of time, ranging from several days up to one year.
Similar to Implant : Challenging Drug Delivery System (20)
Tom Selleck Health: A Comprehensive Look at the Iconic Actor’s Wellness Journeygreendigital
Tom Selleck, an enduring figure in Hollywood. has captivated audiences for decades with his rugged charm, iconic moustache. and memorable roles in television and film. From his breakout role as Thomas Magnum in Magnum P.I. to his current portrayal of Frank Reagan in Blue Bloods. Selleck's career has spanned over 50 years. But beyond his professional achievements. fans have often been curious about Tom Selleck Health. especially as he has aged in the public eye.
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Introduction
Many have been interested in Tom Selleck health. not only because of his enduring presence on screen but also because of the challenges. and lifestyle choices he has faced and made over the years. This article delves into the various aspects of Tom Selleck health. exploring his fitness regimen, diet, mental health. and the challenges he has encountered as he ages. We'll look at how he maintains his well-being. the health issues he has faced, and his approach to ageing .
Early Life and Career
Childhood and Athletic Beginnings
Tom Selleck was born on January 29, 1945, in Detroit, Michigan, and grew up in Sherman Oaks, California. From an early age, he was involved in sports, particularly basketball. which played a significant role in his physical development. His athletic pursuits continued into college. where he attended the University of Southern California (USC) on a basketball scholarship. This early involvement in sports laid a strong foundation for his physical health and disciplined lifestyle.
Transition to Acting
Selleck's transition from an athlete to an actor came with its physical demands. His first significant role in "Magnum P.I." required him to perform various stunts and maintain a fit appearance. This role, which he played from 1980 to 1988. necessitated a rigorous fitness routine to meet the show's demands. setting the stage for his long-term commitment to health and wellness.
Fitness Regimen
Workout Routine
Tom Selleck health and fitness regimen has evolved. adapting to his changing roles and age. During his "Magnum, P.I." days. Selleck's workouts were intense and focused on building and maintaining muscle mass. His routine included weightlifting, cardiovascular exercises. and specific training for the stunts he performed on the show.
Selleck adjusted his fitness routine as he aged to suit his body's needs. Today, his workouts focus on maintaining flexibility, strength, and cardiovascular health. He incorporates low-impact exercises such as swimming, walking, and light weightlifting. This balanced approach helps him stay fit without putting undue strain on his joints and muscles.
Importance of Flexibility and Mobility
In recent years, Selleck has emphasized the importance of flexibility and mobility in his fitness regimen. Understanding the natural decline in muscle mass and joint flexibility with age. he includes stretching and yoga in his routine. These practices help prevent injuries, improve posture, and maintain mobilit
- Video recording of this lecture in English language: https://youtu.be/lK81BzxMqdo
- Video recording of this lecture in Arabic language: https://youtu.be/Ve4P0COk9OI
- Link to download the book free: https://nephrotube.blogspot.com/p/nephrotube-nephrology-books.html
- Link to NephroTube website: www.NephroTube.com
- Link to NephroTube social media accounts: https://nephrotube.blogspot.com/p/join-nephrotube-on-social-media.html
Report Back from SGO 2024: What’s the Latest in Cervical Cancer?bkling
Are you curious about what’s new in cervical cancer research or unsure what the findings mean? Join Dr. Emily Ko, a gynecologic oncologist at Penn Medicine, to learn about the latest updates from the Society of Gynecologic Oncology (SGO) 2024 Annual Meeting on Women’s Cancer. Dr. Ko will discuss what the research presented at the conference means for you and answer your questions about the new developments.
Explore natural remedies for syphilis treatment in Singapore. Discover alternative therapies, herbal remedies, and lifestyle changes that may complement conventional treatments. Learn about holistic approaches to managing syphilis symptoms and supporting overall health.
Anti ulcer drugs and their Advance pharmacology ||
Anti-ulcer drugs are medications used to prevent and treat ulcers in the stomach and upper part of the small intestine (duodenal ulcers). These ulcers are often caused by an imbalance between stomach acid and the mucosal lining, which protects the stomach lining.
||Scope: Overview of various classes of anti-ulcer drugs, their mechanisms of action, indications, side effects, and clinical considerations.
Flu Vaccine Alert in Bangalore Karnatakaaddon Scans
As flu season approaches, health officials in Bangalore, Karnataka, are urging residents to get their flu vaccinations. The seasonal flu, while common, can lead to severe health complications, particularly for vulnerable populations such as young children, the elderly, and those with underlying health conditions.
Dr. Vidisha Kumari, a leading epidemiologist in Bangalore, emphasizes the importance of getting vaccinated. "The flu vaccine is our best defense against the influenza virus. It not only protects individuals but also helps prevent the spread of the virus in our communities," he says.
This year, the flu season is expected to coincide with a potential increase in other respiratory illnesses. The Karnataka Health Department has launched an awareness campaign highlighting the significance of flu vaccinations. They have set up multiple vaccination centers across Bangalore, making it convenient for residents to receive their shots.
To encourage widespread vaccination, the government is also collaborating with local schools, workplaces, and community centers to facilitate vaccination drives. Special attention is being given to ensuring that the vaccine is accessible to all, including marginalized communities who may have limited access to healthcare.
Residents are reminded that the flu vaccine is safe and effective. Common side effects are mild and may include soreness at the injection site, mild fever, or muscle aches. These side effects are generally short-lived and far less severe than the flu itself.
Healthcare providers are also stressing the importance of continuing COVID-19 precautions. Wearing masks, practicing good hand hygiene, and maintaining social distancing are still crucial, especially in crowded places.
Protect yourself and your loved ones by getting vaccinated. Together, we can help keep Bangalore healthy and safe this flu season. For more information on vaccination centers and schedules, residents can visit the Karnataka Health Department’s official website or follow their social media pages.
Stay informed, stay safe, and get your flu shot today!
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Ve...kevinkariuki227
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Verified Chapters 1 - 19, Complete Newest Version.pdf
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Verified Chapters 1 - 19, Complete Newest Version.pdf
Title: Sense of Smell
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the primary categories of smells and the concept of odor blindness.
Explain the structure and location of the olfactory membrane and mucosa, including the types and roles of cells involved in olfaction.
Describe the pathway and mechanisms of olfactory signal transmission from the olfactory receptors to the brain.
Illustrate the biochemical cascade triggered by odorant binding to olfactory receptors, including the role of G-proteins and second messengers in generating an action potential.
Identify different types of olfactory disorders such as anosmia, hyposmia, hyperosmia, and dysosmia, including their potential causes.
Key Topics:
Olfactory Genes:
3% of the human genome accounts for olfactory genes.
400 genes for odorant receptors.
Olfactory Membrane:
Located in the superior part of the nasal cavity.
Medially: Folds downward along the superior septum.
Laterally: Folds over the superior turbinate and upper surface of the middle turbinate.
Total surface area: 5-10 square centimeters.
Olfactory Mucosa:
Olfactory Cells: Bipolar nerve cells derived from the CNS (100 million), with 4-25 olfactory cilia per cell.
Sustentacular Cells: Produce mucus and maintain ionic and molecular environment.
Basal Cells: Replace worn-out olfactory cells with an average lifespan of 1-2 months.
Bowman’s Gland: Secretes mucus.
Stimulation of Olfactory Cells:
Odorant dissolves in mucus and attaches to receptors on olfactory cilia.
Involves a cascade effect through G-proteins and second messengers, leading to depolarization and action potential generation in the olfactory nerve.
Quality of a Good Odorant:
Small (3-20 Carbon atoms), volatile, water-soluble, and lipid-soluble.
Facilitated by odorant-binding proteins in mucus.
Membrane Potential and Action Potential:
Resting membrane potential: -55mV.
Action potential frequency in the olfactory nerve increases with odorant strength.
Adaptation Towards the Sense of Smell:
Rapid adaptation within the first second, with further slow adaptation.
Psychological adaptation greater than receptor adaptation, involving feedback inhibition from the central nervous system.
Primary Sensations of Smell:
Camphoraceous, Musky, Floral, Pepperminty, Ethereal, Pungent, Putrid.
Odor Detection Threshold:
Examples: Hydrogen sulfide (0.0005 ppm), Methyl-mercaptan (0.002 ppm).
Some toxic substances are odorless at lethal concentrations.
Characteristics of Smell:
Odor blindness for single substances due to lack of appropriate receptor protein.
Behavioral and emotional influences of smell.
Transmission of Olfactory Signals:
From olfactory cells to glomeruli in the olfactory bulb, involving lateral inhibition.
Primitive, less old, and new olfactory systems with different path
These simplified slides by Dr. Sidra Arshad present an overview of the non-respiratory functions of the respiratory tract.
Learning objectives:
1. Enlist the non-respiratory functions of the respiratory tract
2. Briefly explain how these functions are carried out
3. Discuss the significance of dead space
4. Differentiate between minute ventilation and alveolar ventilation
5. Describe the cough and sneeze reflexes
Study Resources:
1. Chapter 39, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 34, Ganong’s Review of Medical Physiology, 26th edition
3. Chapter 17, Human Physiology by Lauralee Sherwood, 9th edition
4. Non-respiratory functions of the lungs https://academic.oup.com/bjaed/article/13/3/98/278874
2. Definition
Implants are small sterile solid masses consisting of a highly
purified drug (with or without occupants) made by
compression or molding or extrusion.
Implants are drug delivery systems which provide controlled
delivery of drug over a period of time at the site of
implantation
3. Introduction
Implants are intended for implantation in the body (usually
subcutaneously) for the purpose of providing continuous
release of the drug over long periods of time.
Implants are administered by means of a suitable special
injector or surgical incision.
These are developed with a view to transmit drugs and fluids
into the blood stream without the repeated insertion of
needles
These systems are particularly suited for delivery requirements
of drugs such as insulin, steroids, antibiotics, analgesics,
5. Advantages
Unattended continuous delivery within the therapeutic window
Avoids the highly variable peak and trough concentrations
Enhanced drug efficacy
Minimized side effects
Termination of therapy as and when required
Patient compliance is also a benefit of continuous dosing with
these implants as they operate for a long period of time once
implanted
6. Disadvantages
The reaction between host and implant.
Implantation procedure is difficult in the case of larger
implants.
Inadequate release.
Requires small surgery for large implantation & painful.
8. Classification
A. Rate preprogrammed drug delivery system
Membrane permeation controlled drug delivery.
Matrix diffusion controlled drug delivery.
Membrane matrix hybrid-type drug delivery.
B. Activation modulated drug delivery system
1. Physical activation
Osmotic pressure activated drug delivery
Vapor pressure activated drug delivery
Magnetically activated drug delivery
Phonophoresis activated drug delivery
Hydration activated drug delivery
2. Chemical activation
Hydrolysis activated drug delivery
C. Controlled drug delivery by feed back regulated process
Bioerosion regulated drug delivery
Bioresponsive drug delivery
9. Polymer membrane permeation
controlled drug delivery
Drug reservoir is encapsulated within a spherical compartment that
is enclosed by a rate controlling polymeric membrane.
Drug reservoir : solid particle/dispersion of solid particles in a liquid
or solid dispersion medium
Polymer membrane: nonporous/microporous/semipermeable
Example
NORPLANT subdermal implant
Progestasert IUD
Ocusert system
10. Polymer matrix diffusion controlled drug
delivery systems
Drug reservoir is prepared by homogeneously dispersing drug
particles at a rate controlling polymeric matrix fabricated from
either a lipophilic or hydrophilic polymer
A. NON SWELLABLE POLYMER MATRIX
B. SWELLABLE POLYMER MATRIX
Ex: Compudose subdermal implant
11. Membrane Matrix Hybrid Type Drug Delivery
System
It is a hybrid of Membrane permeation controlled DDS and Matrix
diffusion controlled DDS.
Advantage:
It achieves controlled release kinetics maintained by matrix controlled
DDS.
It minimizes the risk of dose dumping associated with membrane
permeation controlled DDS
Example:
NORPLANT 2 Subdermal Implant
(Levonorgestrol releasing implant)
12. Activation modulated DDS
The release of drug molecules from the delivery system is activated
by some physical, chemical or biochemical process facilitated by an
external energy supplier
In this type of DDS, the drug in solution is released through a
specialized laser drilled delivery orifice at a constant rate under a
controlled gradient of osmotic pressure
External component: Rigid semipermeable housing made up of
substituted cellulosic polymers containing an osmotically active salt.
Internal compartment: Drug reservoir enclosed by a flexible partition
layer and osmotic agent impermeable polyester bag.
Osmotic Pressure Activated Drug Delivery Device
14. Vapor Pressure Activated Drug
In this system, the drug reservoir in a solution formulation, is contained
inside an infusate chamber.
It is physically separated from the vapor pressure chamber by a freely
movable bellows
The vapor chamber contains a vaporizable fluid, which vaporizes at
body temp. & creates a vapor pressure.
Under the vapor pressure created, the bellows move upward & forces
the drug solution in the infusate chamber to release, through a series
of flow regulators & the delivery cannula into the blood circulation at a
constant flow rate.
15. Vapor Pressure Activated Drug
Ex: Infusaid , implantable infusion pump for
- Constant infusion of heparin in anticoagulation treatment
16. Hydration Activated Drug Delivery System
Drug reservoir is homogeneously dispersed in a swellable
hydrophilic polymeric matrix.
After hydration drug molecules are released by diffusing through
the microscopic water saturated pore channels in the swollen
polymeric matrix.
• Ex: Norgestomet releasing HYDRON implant
17. Hydrolysis Activated Drug Delivery
• These systems are prepared from a bio-erodible or bio-degradable
polymer such as polylactide or poly(lactide-glycolide) copolymer
• This device is activated to release the drug upon hydrolysis of polymer
base by tissue fluid at the implantation site.
• Ex: ZOLADEX system
18. Controlled drug delivery by feed back
regulated process
• The release of drug molecules is activated by a triggering system ,
such as a biochemical substance in the body, through some
feedback mechanisms.
• The rate of drug release is regulated by the concentration of the
triggering agent detected by a sensor built in the system.
These are again of two types
A) Bioerosion regulated drug delivery
B) Bioresponsive drug delivery
19. BIO-EROSION REGULATED DDS
• This consists of bio-erodible drug dispersed polymer matrix
fabricated from poly (vinyl methyl ether) half ester , which was
coated with a layer of immobilized urease
• At neutral pH the polymer erodes very slowly
Hydrocortisone release
In the presence of urea, urease metabolizes urea to liberate ammonia
This causes a rise in ph, rapid degradation of polymer and release of
drug release
20. Bioresponsive Drug Delivery
The drug reservoir is contained in a device enclosed by a bioresponsive
polymer membrane whose permeability to drug molecules is controlled
by concentration of biochemical agent in the tissue
Ex: Glucose Triggered Insulin Delivery System
• Insulin reservoir is enclosed within a hydrogel membrane containing pendant
NR2 groups
• In an alkaline solution the pendant NR2 groups exist at neutral state and the
membrane is unswollen and thus impermeable to insulin
• As glucose penetrates the membrane it is oxidized by glucose oxidase
enrapped in the membrane to gluconic acid
• This causes protonation of NR2 groups to NR2 H+
• This causes the membrane to swell and release of insulin
21. Application
A. Cancer Treatment
Gliadel Wafer: Delivers carmustine for the treatment of brain tumours
directly at the site of tumour to prevent reccurrence of tumours.
Depocyte: cytarabine releasing implantable DDS used to treat acute
leukemia.
Duros osmotic pump: Non-biodegradable implantable DDS used to
deliver Leoprolide acetate in the treatment of prostate cancer.
B. Osteoporosis
Micro chips: This device made by ELI Lilly & coworkers used to
deliver Forteo drug used to increase bone density in patients suffering
from severe osteoporosis.
22. D. Contraceptives
Norplant: delivers Norgestrol to achive contraception.
Reactions of host to implant:
Changes in permeability of polymer to body fluids.
Environmental stress cracking.
Chemical breakdown of polymeric material.
Loss of tensile strength in case of hydrophobic polymers.
C. Ocular Diseases
Lacrimedics: these are collagen implants used to treat dry eye syndrome
by partially blocking tear removing canals and they dissolve within 7-10
days.
Vitrasert: delivers ganicyclovir used to treat AIDS related retinitis.
