The systemic action of suppositories

The systemic action of suppositories:
For the systemic action the mucus membrane of the rectum and vagina permit the
absorption of many soluble drugs. A wide variety of the drugs are employed for the systemic
action e.g. analgesic, antispasmodic, sedative(induce sleep), tranquilizers and antibacterial
agents.
Advantages of suppository over oral therapy:
i. Some drugs which are destroyed by GIT enzymes can be administered in the form of
suppositories.
ii. The drugs which cause gastric irritation they may be given rectally in the suppository
form.
iii. To by-pass the first pass action.(the drugs destroyed by portal(liver) circulation may by
pass the liver after rectal absorption.
Example of drugs:
 Glycerol trinitrate (at time of heart attack under tongue)
 Propranolol (antihypertension)
iv. This root of administration is convenient for the adult patient, unconsciousness, mentally
retarted person or for infants who may unable to swallow the medicine.
v. It is also use d for the treatment of the patient with vomiting
vi. In the vaginal cavity for the local episode, antiseptic and antibacterial action.
Example of drugs which are administrated rectally in the form of suppositories for their
systemic action.
 Prochlorperazine (for nausea or vomiting)
 Indomelliacine (analgesic and antipyretic)
 Ergotamine tartarate (used in relief of margarine)
Suppository-base:
 It is an inert medium in which the drug is incperative dissolved suspended or emulsified
for a particular period of time.
 The suppository base play an important role in the release of the medicaments which
they hold and therefore in the availability of drug for absorption to produce systematic or
localized action.
 The bases are used as an emollient, lubricant or as vehicle on the preparation of
medicated suppositories.
The characteristicof an ideal suppository base:
i. It should be good in appearance.
ii. It should melt at body temperature or 37.5c or 37c.

iii. It should completely non-toxic and non-irritating.
iv. Compatible with white variety of drugs.
v. It should be non-sensitizing.
vi. It should shrink sufficiently on cooling to release from mold.
vii. It should be stable on storage.
viii. It should have wetting and emulsifying properties.
ix. It can be manufactured by molding method or compression method.
x. It should be stable if it is heated abouve its melting point
xi. It should keep its shape while it is handling
xii. It should release the medicaments easily
xiii. A high percentage of water can be incoperated which is reffered to as water number (it is
the amount of water in grams which can be incoperative in 100g of fats and it is
expressed as water number)
If the base is fatty it should have following characteristicsd:
i. Acid value should be below 0.2(acid value is the mass of potassium hydroxide in
milligram that is required to neutralized 1g of chemical substance) (saponigated value: it
is the number of milligram of potassium hydroxide required to neutralize the free acids
and sapponified the esters contained in 1g of fat)
ii. Iodine value should be less than 7 (it is the number of grams of iodine that reacts with
100g of fats or other unsaturated material.)
Classification of suppository base:
The suppository base are classified into two main categories according to their physical
characteristics and third group is called as miscellaneous group
1. Fatty or oleaginous
2. Water soluble or water miscible
3. Miscellaneous base which are generally combination of lypophilic and hydrophilic
substance.
Fatty and oleaginous bases:
e.g. cocco butter or theobroma oil
it is defined as fat obtained from roasted seeds of theoromba cacao chemically.
It is triglyceride (combination of glycerin and one or more fatty acid). It is yellowish white solid,
brittle fat which smells and taste like chocolate. Its melting point is between 30c to 35c. Its
iodine value is between 34 to 38. Its acid value is not higher than 4 because cocco butter can
easily melt and rancidity. It must be stored in a cool, dry place and should be protected from
light. It is an ideal suppositories base melt just below body temperature and yet maintaining its
solidity at the usual room temperature. Coco butter exhibits high polymorphism and this
phenomena attributed to the high proportion of unsaturated triglycerides. Each of different form
of coco butter has different melting point as well as different drug release rates.

Different crystalline form of coco butter:
Coco butter has four crystalline states:
1. α-form
2. Β -form
3. Β -1form
4. Γ –form
1) Alpha formThe melting point is 24c in alpha form and it is obtained by suddenly cooling
melted coco butter to 0c
2) The beta form crystallizes out of liquefied coco butter with stirring at 18-23c. its melting
point is lie between 28-31c
3) The beta form changes slowly into the stable form and it melts between 34-35c and this
change is accompanied by volume contraction
4) The gamma form melting point is 18c and it is obtained by pouring cool coco butter into
the container which is then cooled at deep freezer temperature.
The formation of various form of coco butter depends upon:
1. The degree of heating
2. On the cooling process
3. On the condition during these process
Methods to prevent unstable crystalline forms:
1. If the mass is not completed melted the remaining crystals prevent formation of unstable
form.
2. Small amounts of stable crystals added to the melted coco butter which convert unstable
form to stable form and this process is called as seeding.
3. As a journal rule the maximum use of heating in the process to melt the fats is
recommended prolong heating must be avoiding as much as possible
For example: coco butter must be slow and evenly melted preferable on water bath or warm
water to avoid formation of unstable crystal is form.
The problems associated with volatile drug and coco butter:
Some drugs for example volatile oil, camphor, menthol, chlorahydrate lower the melting
point of the coco butter to a considerable extends in such cases. The solidifying agents e.g.
acetyl esters wax 20% or beeswax 4% maybe melted with coco butter to compensate for the
softening effect of the added or volatile substance.
The addition of the hardening agent must not be so excessive that
1. It prevent the melting of the base after the suppositories have been inserted into body
2. It interferes with therauptic agent to alter the efficiency of the product.

The typical treatment of vegetable oil to produce suppositories base:
The fat type suppositories bases are produced from a variety of the materials either synthetic a
natural in origin.
For example: vegetable oil such as coconut oil, cotton seed oil are modified by esterification,
hydrogenation, fractionation at different melting range to obtain the desired product.
The water soluble or water miscible bases:
The main members of this group of the bases are:
1. Glycerol gelatin
2. Polyethylene glycol
1.Glycerol gelatin suppository:
Suppositories may be prepared by dissolving gelatin 20% in glycerine 70% and adding the
solution or suspension of medication 10%. A glycerogelatin base is most frequently used in
preparation of vaginal suppositories where the prolong localized action of the medicinal agent is
usually desired. The glycerol gelatin base is slower to soften mix with physiologic fluid than is
coco butter and therefore provides a more prolong release of drug.
Glycerol gelatin base suppositories have tendency absorb the moisture due to its
hygroscopic nature of the glycerin and they must be protected from atmospheric moisture in
order to maintain their stability and consistency
Due to hygroscopicity of glycerin the suppositories may have a dehydrating effect and maybe
irritating to tissue after insertion.
The water present in formula for suppositories minimize this action however if necessary the
suppositories may be moisture with water prior to their insertion to reduce the initial tendency of
base to draw water from the mucus membrane and irritante the tissue.
The urethral suppositories maybe prepared from glycerol gelatin base. For the urethral
suppositories the gelatin constitute about 60% of the weight of form. The glycerin is about 20%
and the medicated aqueous portion is about 20%.
Methods to prepare suppositories:
Suppositories are prepared by three methods:

The systemic action of suppositories

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