drug delivery systems using biocompatible scaffolds

8/13/2019 Drug Delivery Systems Using Biocompatible Scaffolds

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Wilson Chan

U1021014H

GP05

DRUG DELIVERY SYSTEMS USING BIOCOMPATIBLE SCAFFOLDS

IntroductionDrug delivery system is used to transport drugs into the body at a sustained rate to the

target site produce the necessary therapeutic effect. The process of controlled-release drug

delivery system is about controlling of the time and location of the drug delivery. The rate of

drug release is always independent of the environment, as it focuses on the precision of

control and attempts to minimize any contribution intra and intersubject variability

associated with drug delivery system, thus making it reliable. Sustain-release drug delivery

system reduces the need for frequent dosage, and on occasion, the local or systemic effects.

The choice of appropriate route for both drug delivery systems and fabrication of the

system itself are vital to ensure drugs reach and are released at their targeted sites.

Calcium Alginate encapsulation is evaluated for its efficiency in protecting the drug against

the extreme environments in the body in this experiment. Of many different routes that can

be used to introduce the drug, the oral route is the most convenient and easiest route.

However, the disadvantage of choosing this route is the challenge of passing through the

highly acidic gastrointestinal tract. Different enzymes present along the route change the pH

from mouth to stomach before it reaches the small intestine, which the pH ranges from 2 to

8. The alginate coating protects the drug against the acidic condition in the stomach but will

dissolve spontaneously under alkaline condition in the small intestine.

A common polymer used for drug delivery system is Poly-L-Lactic Acid (PLLA biopolymer)

microsphere. Small in size and exhibiting good permeability, it is ideal for delivery drug in

the bloodstreams. Being biodegradable and possesses minimal harm to the body further

enhance its credibility. It is largely produced by industries today via oil-in-water emulsion

technique as well as, solvent evaporation technique.

Objectives

The objective of this experiment is to test the effectiveness of Calcium Alginate which is

used as on encapsulation for drug delivering systems, by observing the UV release in 2

different medium named simulated intestinal fluid (SIF) and simulated gastric fluid (SGF). On

the other hand, this experiment also allows the observation and characterization of the pure

PLLA microspheres


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ResultsUV spectrometry of sample in water

UV spectrometry of sample in SIF


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UV spectrometry of sample in SGF

Absorbance Value (nm)

Release in water Release in SIF Release in SGF

White Pepper 0.1002 0.13148 0.06584

Note down any observations during the release study

Time, t

(Mins)

Release in water Release in SIF Release in SGF

5 No visible changes Breakage of coating

visible

No visible

changes

10 Enlarge coating Peeling of Surface No visible

changes

15 Cracks on coat

appearing

No visible changes No visible

changes

20 Breakage if coating

and change of color of

solution

No visible changes Coat enlarges

and cracks

appear

25 Coat particles break

off

No visible changes Little coat

particles break

off

30 More coating particles

break off

No visible changes Slightly more

coating particles

break off


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Based on your results, discuss if you think the calcium alginate is effective as

encapsulation

The absorbance value should be higher for SIF samples and lower value for SGF samples,

due to more drugs are being released. However, it does not apply to Calcium Alginate as it is

not totally effective as encapsulation. In this case, there may have been some experimental

errors which caused the absorbance value of SIF to be lower than the SGF value. It may be

caused by the irregular stirring and heating process. Overall, it is effective as it delivers the

drug in the alkaline condition in human body, where the pH is higher than 7 in small

intestines.

Taking the Chinese medicine as an example, if there needs to be 2 outburst release, say

one at 30 minutes and the other at 60 minutes, describe one way in which you can do so.

Double encapsulation can be used. The Chinese medicine can be encapsulated with an outerlayer which is made more porous than the inner encapsulation. In this way, the outer

encapsulation will release the drug while the inner encapsulation stays intact for a period of

time before it releases the drug as well.

PLLA (biopolymer) Microspheres


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Describe the microspheres observed under the optical microscope.

They are spherical and irregularly sized in the range of 100 m to 200 m.

Estimate the size of the microspheres

The sizes of the microspheres are as marked in the picture above. The average size of the

microspheres is 171.65 m.

State factors that would affect the size of the microspheres. Discuss your answer.

The sizes of the microspheres are affected by the concentration of polymer used. Larger sized

microspheres can be obtained with higher concentration of polymer. The force of used to stir can

affect the size of microspheres. Vigorous stirring results in smaller sized microspheres.

drug delivery systems using biocompatible scaffolds

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