Suppositories: Advantages and disadvantages, Ideal requirements and MCQs for GPAT, NIPER, Pharmacist and Drug Inspector exam

A suppository is a solid dosage form in which one or more APIs are dispersed in a suitable base and molded or otherwise formed into a suitable shape for insertion into the rectum to provide local or systemic effect. Suppositories are solid dosage forms intended for insertion into body orifices where they melt, soften, or dissolve and exert local or systemic effects. The derivation of the word suppository is from the Latin supponere, meaning “to place under,” as derived from sub (under) and ponere (to place). Thus, suppositories are meant both linguistically and therapeutically to be placed under the body, as into the rectum.

The advantages of rectal administration include the following:

1. First-pass effect: Avoiding, at least partially, the first-pass effect that may result in higher blood levels for those drugs subject to extensive first-pass metabolism upon oral administration.
2. Drug stability: Avoiding the breakdown of certain drugs that are susceptible to gastric degradation.
3. Large dose drugs: Ability to administer somewhat larger doses of drugs than using oral administration.
4. Irritating drugs: Ability to administer drugs that may have an irritating effect on the oral or gastrointestinal mucosa when administered orally.
5. Unpleasant tasting or smelling drugs: Ability to administer unpleasant tasting or smelling drugs whose oral administration is limited.
6. In children, the rectal route is especially useful. An ill child may refuse oral medication and may fear injections.
7. In patients experiencing nausea and vomiting or when the patient is unconscious.
8. The presence of disease of the upper gastrointestinal tract that may interfere with drug absorption.
9. Objectionable taste or odor of a drug (especially important in children).
10. Achievement of a rapid drug effect systemically (as an alternate to injection).

The disadvantages of suppositories and the reasons given for the infrequent use of suppositories include the following:

1. A perceived lack of flexibility regarding dosage of commercially available suppositories resulting in underuse and a lack of availability.
2. If suppositories are made on demand, they may be expensive.
3. Suppositories as a dosage form are safe, but they exhibit variable effectiveness, depending upon many factors to be discussed later, including the pathology of the anorectal lesions.
4. Different formulations of a drug with a narrow therapeutic margin, such as aminophylline, cannot be interchanged without risk of toxicity.
5. The “bullet-shaped” suppository after insertion can leave the anorectal site and ascend to the rectosigmoid and descending colon. Hence, one may consider that suppositories with this shape possibly should not be used at bedtime.
6. Defecation may interrupt the absorption process of the drug; this may especially occur if the drug is irritating.
7. The absorbing surface area of the rectum is much smaller than that of the small intestine.
8. The fluid content of the rectum is much less than that of the small intestine, which may affect dissolution rate, etc.
9. There is the possibility of degradation of some drugs by the microflora present in the rectum.
10. The dose of a drug required for rectal administration may be greater than or less than the dose of the same drug given orally. This can be dependent upon such factors as the constitution and condition of the patient, the physicochemical nature of the drug, and its ability to traverse the physiologic barriers to absorption, and the nature of the suppository vehicle and its capacity to release the drug and make it available for absorption.
11. The factors that affect the rectal absorption of a drug administered in the form of a suppository may be divided into two main groups: (a) anatomic and physiologic factors and (b) physicochemical factors of the drug and the base.

Ideal requirements:

• It should not reacts with drugs and additives.
• It should have good emulsifying and wetting property.
• It should have acid value less than 0.2 or zero.
• It should have iodine value less than 7.
• It should have saponification no. range between 200-245.

Multiple choice questions:

1.A suppository is a

a)solid dosage form

b)liquid dosage form

c)semi soild dosage form

d) all of these

2.A suppository provide

a)local effect

b)systemic effect

c)both of these

d)none of these

3.Suppositories are intended for

a)oral use

b)ophthalmic use

c)insertion into body orifices

d)external use

4.The advantages of rectal administration include the following

a)First-pass effect avoided

b)More drug stability

c)Ability to administer somewhat larger doses of drugs

d)All of these

5.The disadvantages of suppositories include the following

a)A perceived lack of flexibility regarding dosage of commercially available suppositories resulting in underuse and a lack of availability

b)Different formulations of a drug with a narrow therapeutic margin, such as aminophylline, cannot be interchanged without risk of toxicity

c)The absorbing surface area of the rectum is much smaller than that of the small intestine

d)All of these

6.Ideal requirements of suppositories are

a)It should not reacts with drugs and additives

b)It should have good emulsifying and wetting property

c)It should be transparent

d)a and b

7.Acid value of suppository should be

a)less than 0.2 or zero

b)greater than 0.2 or zero

c)between 1 -2.5

d)between 1 – 1.5

8.Iodine value of suppositories should be

a)greater than 7

b)less than 7

c)equal to 7

d) 10 – 15

9.Saponification no. of suppositories should range between

a)100-200

b)200-245

c)10-100

d)300-350

10.Factors that affect the rectal absorption of a drug administered in the form of a suppository are

a)anatomic and physiologic factors

b)physicochemical factors of the drug and the base

c)both of these

d)none of these

11.Name the possible sites of insertion for suppositories.

a)Rectal

b)Vaginal

c)Urethral

d)All of these

12.The possible shapes of rectal suppositories are

a)Bullet

b)Finger

c)Torpedo

d)All of these

13.Which of the following are local effects of rectal suppositories?

a)Relief of constipation

b)Protective agents

c)Inflammation associated with steroids

d)All of these

14.Physiological factors that may affect the absorption of suppositories are

a)Colonic content

b)Circulation route

c)pH and lack of buffering capacity

d)All of these

15.Which of the following are local effects of vaginal suppositories?

a)Antiseptic

b)Antifungal

c)Yeast infection

d)All of these

Solutions:

1. a)solid dosage form
2. c)both of these
3. c)insertion into body orifices
4. d)All of these
5. d)All of these
6. d)a and b
7. a)less than 0.2 or zero
8. b)less than 7
9. b)200-245
10. c)both of these
11. d)All of these
12. d)All of these
13. d)All of these
14. d)All of these
15. d)All of these

References:

1. Ansels Pharmaceutical Dosage Forms and Drug Delivery Systems, 10th edition, page no. 365-368.

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