NTRODUCTION Rectal drug delivery system means administration of drug or

pharmaceutical preparation via rectum using a mucoadhesive polymer for local or

systemic effect.
Different types of rectal dosage forms –
1. 1. Solid dosage forms- Suppositories.

2. 2. Liquid dosage forms- Enemas, solutions and suspensions.

3. 3. Semisolid dosage forms-Ointments, creams and gels(hydrogels).

ASVANTAGES:
1. 1. Useful for infants ,children and unconscious patients who have difficulty in

swallowing oral medicine.

2. 2. Avoiding first pass metabolism e.g. lidocaine , morphine.

3. 3. In case of nausea and vomiting.

4. 4. Contact of drug with digestive fluid is avoided e.g. Penicillin, vitamins.

5. 5. Drugs which causes gastric irritation or ulceration can be avoided by giving drug

via this route e.g. aspirin, naproxen.

6. 6. Drug absorption may be easily discontinued in case of accidental overdose.

7. 7. Drugs administered per rectum have a faster action than via the oral route and a

higher bio-availability.
8. 8. When oral intake is restricted such as prior to X-ray studies , prior to surgery or in

patients having upper GIT disease.

DISADVANTAGES:
1. 1. Many drugs are poorly or erratically absorbed across the rectal mucosa.
2. 2. Dissolution problem due to small fluid content of the rectum.
3. 3. They are inconvenient and not preferred by patients.
4. 4. Development of proctitis i.e. inflammation of rectum.
APPLICATION:
1. For local effect:
• In case of itching, pain and hemorrhoids.
• Locally active drugs includes astringents, local anesthetics, antiseptics ,
vasoconstrictors, anti- inflammatory drugs, soothing and protective agents and
laxatives.
2. For systemic effects:

 Anti- asthmatic,
 anti- rheumatics,
 analgesics.
Absorption of drugs from the rectum
 Medicaments absorbed in the lower part of the rectum are delivered directly
into the systemic circulation, thus avoiding any first-pass metabolism.
 However, it has been found that suppositories can settle high enough in the
rectum to allow at least some drug absorption into the superior vein.
 Thus keeping the drug in the lower part of the rectum would be advisable.

 Insertion of a suppository into the rectum results in a chain of effects leading to

the bioavailability of the drug.

 Depending on the character of the base, a suppository will either dissolve in the
rectal fluid or melt on the mucous layer.

 Since the volume of rectal fluid is so small, complete dissolution of the base
require extra water.

INTRODUCTION:

 Suppositories are the solid dosage forms meant to be inserted into the body
cavities like rectum, urethra and vagina, where they melt or soften to release
the drugs and exert local or systemic effects.

Classification Of Suppositories
 Rectal suppositories
 Vaginal suppositories ( PESSARIES )
 Urethral suppositories ( BOUGIES )
 Nasal suppositories
 Ear suppositories
 a. Rectal suppositories for adults weigh 2 gm and are torpedo shape.Children's
suppositories weigh about 1 gm.
b. Vaginal suppositories or Pessaries weigh about 3-5gm and are molded in globular
or oviform shape or compressed on a tablet press into conical shapes. Pessaries are
used almost exclusively for local medication. Common ingredients for inclusion in
pessaries for local action include: antiseptics, contraceptive agents , local
anaesthetics
c. Urethral suppositories called bougies are pencil shape. Those intended for males
weigh 4 gm each and are 100-150 mm long. Those for females are 2 gm each and
60-75 mm in length.
d. Nasal suppositories: called nasal bougies or buginaria meant for introduction in to
nasal cavity.They are prepared with glycerogelatin base.They weigh about 1 gm and
length 9-10 cm.
e. Ear cones: Aurinaria and meant for introduction into ear. Rarely used .Theobroma
oil is used as base. Prepared in urethral bougies mould and cut according to size.

Classification Of Suppositories Via Position Of Action

LOCAL EFFECT :
 In case of pain, itching and hemorrhoid.
 Locally active drugs include astringents, antiseptics, local anesthetics,
vasoconstrictors, anti-inflammatory,
 soothing and protective agents and some laxatives.
SYSTEMIC EFFECT :
 Anti-asthmatics, anti rheumatics, anti-pyretic and analgesics

SUPPOSITORIES ADVANTAGES:
 Can exert local effect on rectal mucosa.
 Used to promote evacuation of bowel.
 Avoid any gastrointestinal irritation.
 Can be used in unconscious patients (e.g. during fitting).
 Can be used for systemic absorption of drugs and avoid first- pass
metabolism.
 Babies or old people who cannot swallow oral medication.
 Post operative people who cannot be administered oral medication.
 People suffering from severe nausea or vomiting.
SUPPOSITORIES DISADVANTAGES
 The problem of patient acceptability.
 Suppositories are not suitable for patients suffering from diarrhea.
 In some cases the total amount of the drug must be given will be either too
irritating or in greater amount than reasonably can be placed into
suppository.
 Incomplete absorption may be obtained because suppository usually
promotes evacuation of the bowel.

Formulation of suppositories
1. Bases
2. Anti- oxidants
3. Emulsifying agents
4. Hardening agents
5. Preservatives
6. Thickening agents
7. Plasticizers

1. BASES :They are of two

types :
a. Hydrophilic bases
b. Lipophilic bases
 HYDROPHILIC BASE:

i. water-dispersible bases:
Properties:

 These are mixtures of non-ionic surfactants which are chemically

related to polyethylene glycols.
 These are used alone or in combination with other types of bases
 Cellulose derivatives like methylcellulose sodium carboxy
methylcellulose also come under this class.
 Eg; polyoxyethylene sorbitan fatty acid (tween)

ii) Water soluble bases:

 Glycero-gelatin
 This occurs as a gel .It is a mixture of gelatin, glycerol and water.
 According to B.P the composition of the base is gelatin-14%w/w ,glycerol-
70%w/w
 To get a stiff mass, the quantity of gelatin should be increased to 32%w/w and
that of glycerol reduced to 40%w/w.

LIPOPHILIC BASE:

 Coca butter:
 Properties: It is a natural triglyceride
 It can exist in more than one crystalline form i.e., it exhibits polymorphism
 It consists of mixture of oleic acid , palmitic acid , stearic acid .

COCA BUTTER:
  Theobroma oil, most commonly used as rectal suppository base
 Not suitable for nasal and urethral bougies because of problem of leaking
from body cavities

IDEAL PROPERTIES OF BASE:

 It should be easily molded and should not adhere to the mold.

 It should possess good wetting and emulsifying properties.
 It should be able to incorporate a high percentage of water.
 It should be chemically and physically stable
 Melts or dissolves in the intended body orifice to release the
drug

2. ANTI OXIDANT:
 They protect the drug and the base from getting degraded due to
oxidation.
 Examples :
 Ethyl or propyl gallate
 Ascorbic acid and its ester

3. EMULSIFYING AGENT:
 They increase the water-absorbing capacity of fatty bases. This makes it
possible to include aqueous solutions in the formulation.

 Examples : polysorbates (tween 61) , Wool alcohol , wool fat

4. HARDENING AGENTS:
 These are included in those formulations where the melting point of the
base is decreased by the drug.
 These agents bring the melting point to normal.
 Examples: macrogols with high molecular weight.

5. PRESERVATIVES:
  They should be included in suppositories which contain water soluble
bases to prevent microbial growth.
 Examples :methyl paraben , propyl paraben

6. THICKENING AGENTS:
 They increase the viscosity of molten base and prevent sedimentation of
suspended insoluble solids.
 Examples: Aluminium monostearate ,collodial silica ,magnesium stearate.

7. PLASTICIZERS:
 They impart plasticity to fatty base and makes it less brittle
 Examples : castor oil, glycol, glycerine or propylene glycol

PREPARATION OF SUPPOSITORIES

Suppositories are prepared by four methods:-

1. HAND MOLDING METHOD
2. COMPRESSION MOLDING METHOD
3. POUR MOLDING METHOD
4. AUTOMATIC MOLDING METHOD

1. HAND MOLDING METHOD

  Mix measured quantity of medicinal substances with
sufficient theobroma oil
 Triturate soften with diluted alcohol and rub until
smooth paste is formed
 Add remaining qty of theobroma oil and add wool fat
for consistency
 Remove the mass from the mortar and pestle
 Transfer to a piece of filter paper and keep in hands
during the kneading and rolling procedure
 Roll the mass by quick rotating movements of the
hands and place on a pill tile
 Rolling the mass on the tile with a flat board forms a
cylindrical suppository
 Cut into pieces by spatula
 Give the shape by rolling one end on the tile with
spatula
 Pack in butter paper or in a proper container and store
in a cool place

Advantages:-
 Suitable for thermo labile ingredients.
 Economical for the manufacture of small number of suppositories.
Disadvantages:-
 No uniformity in shape & size of suppository.

2. COMPRESSION MOLDING METHOD

 Mix theobroma oil and drug
 Mixture is forced into a mold under pressure , using a wheel operated press
 Mold is removed , opened , replaced
 On large scale , cold compression machines are hydraulically operated by
water – jacketed cooling and screw fed

Advantages:-
 Suitable for thermo labile drugs.
 No possibility of settling of the insoluble solids in base.
Disadvantages:-
 Rate of production is low so not suitable for large scale.
 Air gets entrapped in the mass which leads to oxidation of ingredients.

3. POUR MOLDING METHOD:

 Drug is dispersed or dissolved in a melted suppository base
 Pour the mixture into a suppository molds and allow cooling in ice bath
 Finished suppositories are removed by opening the mold
 Various types and sizes of molds are available for preparation of suppositories
. Molds are made of aluminium alloys , brass or plastic and are available in 6
to several hundred cavities

Packing of suppositories:-
 It can be foiled in aluminum ,plastic, paper, tin strip.
Labeling:-
 “store in a cool
place.” “Not to
be taken orally.”

Shelf life:
 Most suppositories & Pessaries are stable preparations provided that the packaging
provide adequate protection and that the storage temperature is low.
 An expiry date of 3 months is given to suppositories & Pessaries in the absence of
any official guidance.
 Commercially packed products carry an expiry date recommended by the
manufacturer for products stored appropriately.
 Glycerin and glycerinated gelatin based suppositories are best dispensed in tightly
closed, glass bottles with wide mout