INTRA-UTERINE DRUG DELIVERY SYSTEM
NDDS
B.PHARMA SEMESTER 7
Jsmasipharmacy.blogspot.com
Introduction, advantages and disadvantages,
development of intra uterine devices (IUDs) and applications
What
is an Intrauterine Contraceptive Devices (IUD)?
IUD’s are
medicated or non-medicated devices which exerts it’s contraceptive action in
the uterine cavity continuously for a prolonged period of time without
requiring patients motivation.
How
Does an IUD Work?
An IUD prevents sperm from meeting an egg. An IUD
may stop a fertilized egg from growing inside the uterus
Types
of IUD’s:
1. Non-medicated IUD’s: Contraceptive action by producing sterile inflammatory response in Endometrium. These are available in ring shaped IUD’s made up of s.s and plastic fabricated form polyethylene, polypropylene.
2. Medicated
IUD’s: - Copper IUD’s
Progesterone
releasing IUD’s
Copper
bearing IUD’s:
A)
7-Shaped IUD:-
·
Further development of the concept of
intra-uterine contraception by metallic copper has resulted in copper barring
IUD, which contains 89mg copper wire, wound around the vertical limb of a
7-shaped polypropylene device, to give an effective surface of approximately
200mm2 used for 3years as intra-uterine contraceptive treatment.
·
This device release copper ion at a mean
daily dose of 9.87µg/day continuously in the uterine cavity for up to 40 months.
·
The Cu-7 appears to be substantially
smaller then other.
·
It can be easily inserted because of
it’s special 7-configuration in addition to its small size.
·
Insertion can usually be accomplished without
the need for cervical dilation and further more removal is generally painless.
B)
T-Shaped IUD’s
·
T-shaped IUD containing 200mm2 contraceptive
copper wire winding around the vertical leg of a T-shaped polyethylene device
in the manner as copper-7 device.
·
It is used for 3years of contraceptive
treatment.
·
This T-shaped device has a volume of
0.16cm3,which is almost twice as large as the 7-shaped device.
C)
New development of copper bearing IUD’s:
·
The Cu-T-380A with 2 collars of copper
positioned on the transverse arms of the letter T. Each collar provides an
additional surface area of 30mm2. It has relatively small surface
area of copper but effective than Cu-T-200.
·
Another new version of copper bearing IUD:
The combined multi load copper IUD (MLCU-250) was also introduced. It is a compromise between Cu-T IUD, but without the central plastic membrane and has a surface area of 250mm2 copper wire. The blunt apex of the device fits into the vault of the uterine cavity without penetrating the endometrial walls and its two arms studded side arms fully adapt to the contours of the uterine cavity.
Potential
development
1.
Membrane
controlled reservoir-type drug delivery system:
These drug delivery devices consist of a polymeric
membrane that both encapsulates and controls the release of contraceptive agent
·
Single
component system: In this system the contraceptive agent
is encapsulated in its pure solid form in a capsule fabricated form
bio-compatible polymeric materials (silicon elastomers and polyethylene-
polymers) The release of contraceptive agent such as progesterone follows
essentially zero-order kinetics.
·
Multi
component system: In this system a constant drug release
profile is maintained by encapsulating a liquid medium saturated with excess
drug profiles in a rate-controlling polymeric membrane.
2.
Polymer
matrix diffusion controlled drug delivery devices:
This drug delivery device is prepared by
homogenously dispersing the drug particles in a crossed linked polymeric
matrix.
·
Retrievable
matrix device: This drug delivery system is designed
for feasibility of retrieval at termination of treatment. It can be easily
fabricated from silicone elastomers by premixing a drug in powder form with a
semisolid silicone elastomers before vulcanization at room or low temperature
or from polyethylene by dry mixing. The rate of drug release is not constant
but time dependent.
·
Bio-degradable
matrix device: This drug delivery system is designed
to eliminate the need for retrieving at the end of treatment it can be prepared
by dissolving such a poly lactic acid, in a common organic solvent to dryness,
to produce drug dispersing biodegradable matrix devices of varying shapes and
sizes, The rate of drug-release from this type of drug delivery system is a
combination of polymer hydrolysis and drug diffusion.
MECHANISM
OF ANTIFERTILITY ACTION OF COPPER:
·
Copper is known to be cytotoxic in high
concentration it enhances the spermatocidal and spermato depressive action of
an IUD.
·
The copper concentration in endometrial
epithelium and superficial stromata inhibits the binding of steroids of their
receptors.
·
Cupric ion inhibits the binding of 17-β-
estradiol to human endometrial cytosol.
·
Cupric ions shows only little effect on
sperm motility.
·
Copper wire was also “Blastocystocidal”.
·
A copper bearing IUD was reported to produce
significant effects like:
o
Increased alkaline phosphate activity in
uterine fluids and endometrium tissue.
o
No change of acid phosphate activity in
uterine fluid but its concentration in endometrium tissue increases.
Advantages
of the IUD:
·
Provides long-term birth control.
·
Cost effective.
·
Can be removed when a woman would like to
become pregnant.
·
Convenient - a woman does not need to
remember it daily or weekly.
Disadvantages
of an IUD:
·
Between 2 and 10% fall out, most
commonly in the first year of use.
·
Increased risk of miscarriage if an IUD is
left in the uterus during pregnancy.
·
In rare cases, the IUD may attach to or perforate
the wall of the uterus.
·
With the copper IUD, a woman may experience
heavier bleeding and cramping with periods.