1. 1
RECTAL DRUG
DELIVERY SYSTEM
Presented By:-
KAMLESH A. WADILE
(M. Pharmacy)
Department of Pharmaceutics
R. C. Patel Institute of Pharmaceutical Education & Research, Shirpur.
2. 1. Introduction
2. Anatomy & physiology of rectum
3. Absorption from rectum
4. Factor influencing drug absorption
5. Optimization of drug absorption
6. Criteria for drug selection
7. Suppository
8. Enemas
9. Rectal capsule
10. Evaluation
11. Advantages
12. Disadvantages
13. Applications
14. Conclusion
15. References
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3. • History:
In the 18th century, a French pharmacist, Baume used rectal
route for administration of suppositories.
• Definition:
“Rectal drug delivery system means administration of
drug or pharmaceutical preparations via rectum for local or
systemic effect.”
example: suppositories, rectum capsules, enemas, etc.
• Rectal products may be:
1. Solid unit dosage form: Suppository.
2. Liquid unit dosage form: Enema.
3. Semi-solid dosage form: Ointment, Cream.
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4. 4
The rectum is about 15 to 20
cm long and 1.5 to 2 cm
width.
It hooks up with the sigmoid
colon and with the anal
canal.
It is a hollow organ with a
relatively flat wall surface,
without villi and the rectal
valves.
The rectal wall is formed by
an epithelium which one cell
layer thick.
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The rectal tissues are
drained by the inferior,
middle and superior
haemorrhoidal veins,
but only the superior
vein connects with the
hepatic-portal system.
6. The transverse folds in rectum keep stool in place until the
person is ready to go to the toilet.
Rectum contains about 2 to 3 ml of mucous, which has a
pH of 7.4.
The entire surface area of rectum is 200-400 cm2.
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7. Medicaments absorbed in the lower part of the rectum are
delivered directly into the systemic circulation, thus avoiding any
first-pass metabolism.
Thus keeping the drug in the lower part of the rectum would be
advisable.
The drug in unionize with high partition coefficient is readily
absorbed.
However, it has been found that suppositories can settle high
enough in the rectum to allow drug absorption.
The process of absorption will be passive diffusion.
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8. A. Physiological factors:
1. Quantity of dissolution fluid available:
Very small volume under normal conditions.
Under non-physiological conditions the volume is enlarged.
Thus, absorption of slightly soluble drugs will be dissolution
rate limited.
(e.g. phenytoin)
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9. 2. Properties of rectal fluids
Composition, viscosity and pH of rectal fluids have great
effects on drug bioavailability.
3. Contents of the rectum
Faecal content
4. Motility
Upright position
Wave of contraction from colon
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10. B. Physiochemical factors:
1. Solubility:
Higher the solubility, consequently higher the
dissolution rate and better is absorption.
2. Degree of ionization:
At the alkaline pH of rectal mucosa, basic drugs will
exist in their unionized form and readily absorbed.
3. Particle size:
The smaller the size, the more readily the dissolution
of the particle and the greater the chance for rapid
absorption.
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4. pH:
Rectal content is slightly alkaline (pH 7-8) , so alkaline
drugs are quickly absorbed than acidic drugs.
5. Partition Coefficient:
Higher the partition coefficient of drug, more readily
absorption of drug.
12. Absorption enhancing agent:-
e.g. salicylates
bile salts
fatty acid
pH control
Solubilizing agents
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13. Drugs requiring high therapeutic dose.
Drugs with swallowing difficulties.
Drugs that are substrates for proteolytic activity in upper GI
tract.
Ex. Proteins & Peptides.
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14. “Suppository is solid unit dosage form used for rectal
administration and which is composed of active drug molecule
with water soluble or fatty bases.”
The suppository melt at body temperature and weight
is vary in 1g (children) to 2.5g (adults).
TYPE OF BASES:
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BASES M.P. (°C) SOLIDIFICATION
POINT (°C)
Fatty Bases
1) Cocoa butter 30-35 24
2) Hard butter 36-45 32-40
Water Soluble Bases
1) PEG 38-49 38-42
2) Tween 61 35-49 -
15. Hand molding:
The base and other ingredients are triturated well then rolled
into a uniform cylinder with a large spatula and cut that cylindrical
suppository mass into required size piece.
Compression molding:
In the compression molding, the suppository mass is placed
into a cylinder which is then closed.
Pressure is applied from one end to release the mass from the
other end into the suppository mold or die.
The additional pressure is applied to mass in the die, the
formed suppository ejected.
Pour molding:
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16. Finished suppositories are routinely inspected for:
• Appearance
• Content uniformity
• Melting range test
• Drug release test
• Fragility test
• Disintegration test
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17. Evacuant Enema:
Volume may be up to 2 liters.
e.g.- soft soap enemas
Retention Enemas:
Volume does not exceed 100 ml.
e.g.- Prednisolon enemas
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19. In vivo evaluation:-
rats
rabbits
dogs
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20. In vitro evaluation
In in vitro testing mainly the study is conducted for evaluation
of correlation between drug structure and transport.
For permeation studies mainly the diffusion cell is used.
e.g. Ussing chamber
In this cell two compartments are present i.e. donor and
receiver compartment. In donor compartment drug solution is
added and the sample is received from receiver.
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21. Another in vitro model that has experienced significant growth
in utilization of drug transport studies and which may provide
useful information relative to rectal drug absorption is cultured
cell monolayers.
HT-29 and Caco-2 cells are two cell lines commonly used.
Limitation
Less leaky
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22. Infants and children, who have difficulty in swallowing oral
medicine.
Avoidance of first pass metabolism when given orally.
example- Lidocaine, Morphine.
In cases of nausea and vomiting act.
Its contact with digestive fluid is avoided.
example- Penicillin, vitamins.
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23. Drugs which causes gastric irritation or ulceration are
administered in rectum.
example- Aceclofenac.
Drug absorption may be easily discontinued in an events of
accidental overdose.
Drug absorption is not influenced by ingestion of food and the rate
of gastric empting.
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24. Surface area of rectum is far small for absorption.
Fluid content of rectum is much smaller.
Microbial degradation may occur in rectum.
Patient acceptability may be a problem.
Development of proctitis.(inflammation of rectum)
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25. Local effect:
• In case of pain, itching and hemorrhoids
• Locally active drugs include astringents, antiseptics, local
anesthetics, vasoconstrictors, anti-inflammatory drugs,
soothing and protective agents and some laxatives
Systemic effect:
• Anti-asthmatics, anti-rheumatics and analgesics.
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26. We conclude that, it is necessary not only to develop new drugs
but also to optimize the different routes of administration, so as to
increase effectiveness and minimize adverse effects.
Rectal drug delivery with the advantages of enhancement in drug
absorption and avoidance of first pass metabolism will
undoubtedly be a pioneer in formulation of various challenging
compounds.
So, by improving some techniques towards good patient
acceptability, rectal administration may lead to more widely
employed route of drug administration.
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27. 1. Lakshmi Prasanna J., Deepthi B. and Rama Rao N., Rectal drug delivery: A
promising route for enhancing drug absorption, Asian Journal of Research
in Pharmaceutical Science, 2012, Vol-2, page no.:143-149.
2. Pushkar Baviskar, Anjali Bedse, Sayyed Sadique, Vikas Kunde and
Shivkumar Jaiswal, Drug Delivery on Rectal Absorption: suppositories,
International Journal of Pharmaceutical Science, 2013,(21)1, page no.: 70-
76.
3. D. M. Brahmankar and S. B. Jaiswal, Biopharmaceutics and
Pharmacokinetics a treatise, second edition, 2009, Vallabh prakashan,
page no.- 83.
4. Ross and Wilson , Anatomy and Physiology in Health and illness, Churchill
Livingstone, 11th edition, page no.: 277-290.
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28. 5. James Swarbrick and James C. Boylan, Encyclopedia of
Pharmaceutical Technology, second edition, volume 1, A-
D, pages 1-1032, page no.932-943.
6. www.encyclopedia.com/rectal drug delivery
(01/03/2016, 01:30pm)
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“No single method of drug
administration is ideal for all
drugs in all circumstances”