The document summarizes a seminar on rate-controlled drug delivery using preprogrammed drug delivery systems. It describes different types of rate-preprogrammed systems including polymer membrane permeation systems, polymer matrix diffusion systems, and micro reservoir partition systems. It also discusses activation-modulated drug delivery systems that use physical, chemical, or biological means like osmotic pressure, hydrodynamic pressure, magnetism, or ultrasound to activate and control drug release. Specific examples of commercial drug delivery systems are provided for different technologies.
Pulmonary drug delivery (PDD) systems were recently introduced into the pharmaceutical field to treat both the local and the systemic types of lung diseases. PDD systems are known to be able to simply deliver the drug to the required site in the body directly or to other distant sites through the bloodstream.
Penetration Enhancers in Transdermal Drug Delivery SystemSimranDhiman12
Penetration Enhancers in Transdermal Drug Delivery System
Permeation enhancers are substances that reduce the skin barrier's ability to make skin more permeable and allow drug molecules to cross the skin at a faster rate
advantages and disadvantages
types of penetration enhancers
techniques
physical and chemical enhancers
Adhesion describes the attractive forces between a biological material and mucus or mucous membrane. 1. Mucous membranes adhere to epithelial surfaces such as the gastrointestinal tract (GI-tract), the vagina, the lung, the eye, etc. They are generally hydrophilic as they contain many hydrogen macromolecules due to the large amount of water (approximately 95%) within its composition. However, mucin also contains glycoproteins that enable the formation of a gel-like substance. 1. Understanding the hydrophilic bonding and adhesion mechanisms of mucus to biological material is of utmost importance in order to produce the most efficient applications. For example, in drug delivery systems, the mucus layer must be penetrated in order to effectively transport micro- or nanosized drug particles into the body. 2 Bioadhesion is the mechanism by which two biological materials are held together by interfacial forces.
Pulmonary drug delivery (PDD) systems were recently introduced into the pharmaceutical field to treat both the local and the systemic types of lung diseases. PDD systems are known to be able to simply deliver the drug to the required site in the body directly or to other distant sites through the bloodstream.
Penetration Enhancers in Transdermal Drug Delivery SystemSimranDhiman12
Penetration Enhancers in Transdermal Drug Delivery System
Permeation enhancers are substances that reduce the skin barrier's ability to make skin more permeable and allow drug molecules to cross the skin at a faster rate
advantages and disadvantages
types of penetration enhancers
techniques
physical and chemical enhancers
Adhesion describes the attractive forces between a biological material and mucus or mucous membrane. 1. Mucous membranes adhere to epithelial surfaces such as the gastrointestinal tract (GI-tract), the vagina, the lung, the eye, etc. They are generally hydrophilic as they contain many hydrogen macromolecules due to the large amount of water (approximately 95%) within its composition. However, mucin also contains glycoproteins that enable the formation of a gel-like substance. 1. Understanding the hydrophilic bonding and adhesion mechanisms of mucus to biological material is of utmost importance in order to produce the most efficient applications. For example, in drug delivery systems, the mucus layer must be penetrated in order to effectively transport micro- or nanosized drug particles into the body. 2 Bioadhesion is the mechanism by which two biological materials are held together by interfacial forces.
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
Transdermal Drug Delivery System (TDDS) is the one of the novel technology to deliver the molecules through the skin for long period of time.
Transdermal Drug Delivery System (TDDS) are defined as self contained, discrete dosage forms which are also known as “patches” 2, 3 when patches are applied to the intact skin, deliver the drug through the skin at a controlled rate to the systemic circulation
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
Transdermal Drug Delivery System (TDDS) is the one of the novel technology to deliver the molecules through the skin for long period of time.
Transdermal Drug Delivery System (TDDS) are defined as self contained, discrete dosage forms which are also known as “patches” 2, 3 when patches are applied to the intact skin, deliver the drug through the skin at a controlled rate to the systemic circulation
Controlled Release Oral Drug Delivery System
Controlled drug delivery is one which delivers the drug at a predetermined rate, for locally or systemically, for a specified period of time.
it describes the controlled drug release by diffusion or dissolution or both or swelling or erosion and which kinetics it follows either zero,first , higuchi or peppas
These systems are capable of controlling the rate of drug delivery, sustaining the duration of therapeutic efficacy, and/or targeting the delivery of drug to a tissue. Depending upon the technical sophistication, these rate-control drug delivery systems can be classified into three major categories: (i) pre-programmed drug delivery, (ii) activation-controlled drug delivery, and (iii) feedback-regulated drug delivery.
rate control drug delivery system machenism Nirmal Maurya
rate control drug delivery system
including all machenism with figures
Prepared by
NIRMAL MORYA
M.Pharma
Mob +91 7060346038
BBAU Lucknow
A Central University
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.
Description about a type of activation modulated drug delivery system, which a type of control drug delivery system.
Also, give a detailed description about each subclassification.
CrDDS is one which delivers the drug at a predetermined rate, for locally or systematically, for a prolong period of time.
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.
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4. CLASSIFICATION
Rate- preprogrammed drug delivery systems
Activation – modulated drug delivery systems
Feedback- regulated drug delivery systems
Site- targeting drug delivery systems
4
5. RATE- PREPROGRAMMED DDS
Release of drug molecules from the delivery systems has been
preprogrammed at specific rate profiles
Diffusion of drug molecules into the medium is controlled
CLASSIFICATION OF RATE- PREPROGRAMMED DDS
A. Polymer membrane permeation-controlled drug delivery systems
B. Polymer matrix diffusion-controlled drug delivery systems
C. Micro reservoir partition-controlled drug delivery systems
5
6. A. POLYMER MEMBRANE PERMEATION-CONTROLLED
DDS
Drug release surface of the reservoir compartment is rate-
controlling polymeric membrane.
Polymeric membrane can be nonporous, microporous or
semi permeable in nature.
Encapsulation of drug in the reservoir is accomplished by
injection molding, spray coating, capsulation or
microencapsulation.
Q/t = [(Km/r Ka/m Dd Dm)/( Km/r Dm hd + Ka/m Dd hm)] cR
6
7. Release of drug is controlled by controlling the partition
coefficient and diffusivity of the drug molecule and the
thickness of the rate-controlling membrane
EXAMPLES
PROGESTASERT IUD:
reservoir - suspension of progesterone crystals in silicone
medical fluid
Membrane- nonporous membrane of ethylene vinyl acetate
copolymer
Deliver natural progesterone continuously in the uterine cavity
at a daily dosage rate of at least 65 µg/day to achieve
contraception for1 year.
7
9. OCUSERT SYSTEM
thin disk of pilocarpine alginate complex sandwiched
between two transparent sheets of microporous ethylene-
vinyl acetate copolymer membrane.
9
10. Either 20 or 40 µg/hr of pilocarpine is released
TRANSDERM-NITRO
Nitroglycerin-lactose triturate in the silicone medical fluid
Micro porous membrane of ethylene-vinyl acetate
copolymer
Thin layer of pressure-sensitive silicone adhesive polymer is
coated
10
11. B. POLYMER MATRIX DIFFUSION-CONTROLLED DDS
Reservoir is prepared by homogenously dispersing drug particles in
a rate-controlling polymer matrix.
11
12. Q/t1/2 = (2ACRDp)1/2
release of drug is controlled by controlling the loading
dose, polymer solubility of the drug, and its diffusivity in the
polymer matrix
EXAMPLES
NITRO-DUR
Nitro-glycerine transdermal patch
for 24 hr to provide a continuous transdermal infusion of
nitro-glycerine at a dosage rate of 0.5 mg/cm2/day for the
treatment of angina pectoris.
12
14. C. MICRORESERVOIR PARTITION- CONTROLLED DRUG DELIVERY
SYSTEMS
Micro dispersion of an aqueous suspension of drug using a high-
energy dispersion technique in a bio-compatible polymer,(Eg.
silicone elastomers), forms a homogenous dispersion of many
discrete, unleachable, microscopic drug reservoirs.
device can be further coated with a layer of biocompatible polymer
to modify the mechanism and the rate of drug release
14
15. Release of drug molecules from this type of CRDDS can
follow either dissolution or a matrix diffusion-controlled
process depending upon the relative magnitude of Sl and Sp
EXAMPLES
NITRODISC SYSTEM
Nitro-glycerine in silicone elastomer
0.5mg/cm2 for once-a-day
15
16. ACTIVATION MODULATED DDS
Drug delivery is activated and controlled by physical, chemical or bio-
chemical processes or facilitated by the energy supplied externally
Classification of activation modulated DDS
Based on the nature of the process applied or the type of energy used
1. Physical means
2. Chemical means
3. Biological means
16
17. DDS activated by physical means
a. Osmotic pressure- activated DDS
b. Hydrodynamic pressure activated DDS
c. Vapour pressure activated DDS
d. Mechanically activated DDS
e. Magnetically activated DDS
f. Sonophorosis activated DDS
g. Iontophoresis activated DDS
h. Hydration activated DDS
17
18. 1. Osmotic pressure- activated DDS
drug reservoir can be a solution contained within an impermeable
collapsable tube.
This is covered with osmotic agent place in a rigid semi permeable
housing with controlled water permeability.
The rate of drug release is modulated by the gradient of osmotic
pressure.
Q/t = PwAm (πs-πe) /hm
Pw = water permeability
Am = effective surface area
hm =thickness of the semi permeable housing 18
20. 2. Hydrodynamic pressure activated DDS
hydrodynamic pressure is used as the source of energy to activate
the drug release.
20
21. Q/t = Pf Am/hm (θs – θe)
Pf = fluid permeability
Am = effective surface area
hm = thickness of the wall with annular openings
θs – θe = difference in hydrodynamic pressure between the
DDS and the environment
21
22. 3. Vapour pressure- activated drug delivery systems
Drug inside infusion compartment is separated from pumping
compartment by freely movable partition.
Pumping compartment contains a fluorocarbon fluid that
vaporizes at body temperature
The vapour pressure created moves the partition
upward, forcing the drug to be delivered.
Eg: INFUSAID implants (heparin)
22
24. Q/t= d4(Ps-P-e)/40.74µl
d & l = the inner diameter and the length of the delivery
cannula, respectively
Ps-P-e = difference between the vapour pressure in the
pumping compartment and the site of implantation.
µ = viscosity of the drug formulation used.
24
25. 4. Mechanically activated drug delivery system
Equipped with a mechanically activated pumping system
A measured dose of drug formulation is reproducibly delivered
The volume of solution delivered is controllable, as small as 10-
100µl
Volume of solution delivered is independent of the force &
duration of activation applied as well as the solution volume in the
container.
Example is the development of metered dose nebulizer for the
intranasal administration of a precision dose of buserelin (LHRH).
25
27. 5. Magnetically activated drug delivery systems
Drug reservoir is a dispersion of peptide or protein powders in a
polymer matrix
Low rate of delivery is improved by incorporating
electromagnetically triggered vibration mechanism
27
28. Coating polymer can be a ethylene-vinyl acetate copolymer or
silicon elastomers.
These systems have been used to deliver protein drugs, such as
bovine serum albumin
6. Sonophoresis-activated drug delivery systems
Utilize ultrasonic energy to activate the delivery of the drugs from
a polymeric drug delivery device
can be fabricated from either a non degradable polymer, such as
ethylene-vinyl acetate copolymer,
a bio erodible polymer such as poly[bis(p-carboxyphenoxy)alkane
anhydride].
28
30. 7. Iontophoresis-activated drug delivery systems
uses electrical current to activate and to modulate the
diffusion of a charged drug molecule across the skin in a
facilitated rate
30
31. skin permeation rate of a charged molecule i consist of 3 components
Jiisp = Jp+Je+Jc
Jp = passive skin permeation flux
Je = electrical current driven permeation flux
Jc = convection flow-driven skin permeation flux
IONSYS - fentanyl iontophoretic transdermal system
Example : development of an iontophoretic DDS of dexamethasone
sodium phosphate
31
32. 8. Hydration-activated drug delivery system
Depends on the hydration induced swelling process to activate the
release of drug
Drug reservoir is homogeneously dispersed in a swellable polymer
matrix fabricated from a hydrophilic polymer
Release of the drug is controlled by the rate of swelling of the polymer
matrix.
Example is VALRELEASE tablet- diazepam in hydrocolloid and
pharmaceutical excipients.
In stomach absorbs the gastric fluid & forms colloidal gel that starts
from the tablet surface and grows inward.
32
33. release of the drug is controlled by matrix diffusion through this
gel barrier
33
34. REFERENCES
NOVEL DRUG DELIVERY SYSTEMS, 2nd edition,Yie W. Chien
CONTROLLED DRUG DELIVERY- FUNDAMENTALS AND
APPLICATIONS, 2nd edition, edited by Joseph R. Robinson and
Vincent H. L. Lee
http://www.rxlist.com/ionsys-drug.htm
34