Pharmaceuticals: Suppositories and Pessaries

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Questions and Answers

What is a characteristic of an ideal suppository base?

It should be stable on storage. (correct)

It should be highly irritating.

It must dissolve quickly in oil.

It should react strongly with medications.

How does the melting point of a suppository base affect drug release?

Melting point has no effect on drug action.

A melting point at body temperature promotes drug release. (correct)

A higher melting point increases absorption.

A lower melting point slows down drug action.

What can happen if a base interacts negatively with the drug?

Drug stability will improve.

The drug will be absorbed effectively.

Drug absorption can be impaired or prevented. (correct)

The base will always enhance the drug effect.

Which component is NOT a characteristic of fatty bases used in suppositories?

Highly hydrophilic. Signup and view all the answers

What effect does an irritating base have on the digestive system?

It can initiate a colonic response and cause bowel movement. Signup and view all the answers

Which type of base is Cocoa butter categorized as?

Fatty base. Signup and view all the answers

Why is it important for a suppository base to be easily molded?

It facilitates manufacturing and allows easy removal from molds. Signup and view all the answers

What is a potential drawback of using a poorly designed suppository base?

Incomplete drug release and absorption. Signup and view all the answers

Which of the following is a characteristic of hydrophilic bases?

They dissolve rather than melt. Signup and view all the answers

What is a disadvantage of glycerogelatin bases?

They may lead to rectal irritation. Signup and view all the answers

Which of the following is an example of a water-soluble base?

Glycerogelatin Signup and view all the answers

What is the primary component of the glycerol suppository base according to the BP standard?

70 % Signup and view all the answers

What can happen due to the hygroscopic nature of glycerogelatin?

Dehydration of rectal mucosa Signup and view all the answers

What is one important characteristic of an ideal glycerogelatin suppository?

Non-gritty texture Signup and view all the answers

What is a risk associated with glycerogelatin suppositories?

Unpredictable drug effect Signup and view all the answers

Why should glycerogelatin bases be stored in tight containers?

To limit moisture absorption Signup and view all the answers

What is the approximate quantity of fluid available for drug dissolution in the rectum?

3 ml Signup and view all the answers

What is the ideal characteristic of drugs used rectally regarding their solubility?

High aqueous solubility Signup and view all the answers

What effect does particle size have on drug absorption in rectal administration?

Smaller particles lead to faster dissolution Signup and view all the answers

How does the state of the rectum (full or empty) impact drug absorption?

Empty rectum facilitates rapid absorption Signup and view all the answers

What is the role of the partition coefficient in drug absorption?

Determines solubility in base and rectal fluid Signup and view all the answers

What is a characteristic of rectal fluids concerning pH?

Neutral pH between 6.5 and 8 Signup and view all the answers

What happens to drug absorption when using slightly soluble drugs in the rectum?

Absorption is slow due to dissolution being rate-limiting Signup and view all the answers

What effect does a full rectum have on drug absorption?

Delays drug dissolution and absorption Signup and view all the answers

What happens to cacao butter suppositories when the percentage of solid exceeds 30%?

They may become brittle. Signup and view all the answers

What is a recommended additive to reduce brittleness in cacao butter suppositories?

Tween 80 Signup and view all the answers

What is the acceptable deviation for the weight of any suppository from the average weight?

No more than 10% Signup and view all the answers

What should the drug content in each suppository not deviate from?

90-110% of labeled content Signup and view all the answers

What temperature should the water bath be for the liquefaction time test?

37° C Signup and view all the answers

What is the purpose of the breaking test for suppositories?

To measure brittleness or fragility Signup and view all the answers

Which of the following characteristics should NOT be present in the appearance of suppositories?

Air bubbles or cracks Signup and view all the answers

How many suppositories should be assayed for drug content uniformity?

20 suppositories Signup and view all the answers

What is the main reason cocoa butter must be slowly melted over a warm water bath?

To avoid the formation of unstable crystalline forms Signup and view all the answers

What happens if cocoa butter is quickly heated and then cooled suddenly?

It forms unstable α or γ crystals Signup and view all the answers

What is a disadvantage of cocoa butter regarding its adherence to molds?

It does not contract sufficiently on cooling Signup and view all the answers

What is the suitable melting point range of cocoa butter for it to remain solid?

30-36 °C Signup and view all the answers

How do some drugs like phenol and chloral hydrate affect cocoa butter's melting point?

They lower the melting point Signup and view all the answers

What agent can be added to cocoa butter to raise its melting point when certain drugs are present?

Castor oil Signup and view all the answers

What is a potential issue with cocoa butter during storage?

It may become rancid Signup and view all the answers

What method can help in reducing the sticking of cocoa butter suppositories to the mold?

Using adequate soap lubrication Signup and view all the answers

What is a primary advantage of using soap glycerin for suppositories?

It allows for a larger incorporation of glycerin. Signup and view all the answers

Which of the following is a disadvantage of soap glycerin in suppository formulation?

It contributes to local tissue irritation. Signup and view all the answers

Why should water be avoided in suppository preparations?

It can support bacterial and fungal growth. Signup and view all the answers

What factor affects the hygroscopicity of PEG bases?

Chain length of the molecule. Signup and view all the answers

What issue can lead to brittleness in suppositories?

Low viscosity during manufacturing. Signup and view all the answers

What can be added to increase the viscosity of suppositories if it is too low?

Silica gel. Signup and view all the answers

What is a drawback of glycerogelatin suppositories in relation to humidity?

They may absorb moisture in humid conditions. Signup and view all the answers

Which statement is true regarding the use of fat in suppository formulations?

Fats accelerate drug crystallization at high temperatures. Signup and view all the answers

Study Notes

Suppositories and Pessaries

Suppositories are medicated, molded solid dosage forms of various sizes and shapes designed for insertion into body cavities (rectum, vagina, or urethra).
Suppositories are inserted into the rectum.
Pessaries are inserted into the vagina.

Types of Suppositories

Rectal suppositories: conical or torpedo shape, ~2-3 cm length.
- Adult dose: ~2 gm
- Child dose: ~1 gm
Urethral suppositories (Bougies): cylindrical or tube shape in globular or oval form, ~3-6 mm diameter.
- Adult dose: ~4 gm
- Child dose: No data given
Vaginal suppositories (pessaries): cylindrical or tube shape in globular (ball), oval or cone-shaped, ~4-5 gm in weight.

Action of Suppositories

When inserted into the body, suppositories and pessaries either melt, soften, or dissolve, and exert a local or systemic effect.

Advantages of Suppositories

Local effect:
- Treat infections, pain and inflammation (e.g., hemorrhoids, vaginal fungal infections).
- Relieve constipation.
- Treat diseases of the colon (e.g., ulcerative colitis).
Systemic effect:
- For babies or elderly unable to swallow oral medication.
- Post-operative patients.
- People with nausea or vomiting.
- Drugs irritating to the stomach.
- Drugs destroyed by the pH or enzymatic activity of the stomach or intestine
- Drugs destroyed by portal circulation (bypass first-pass metabolism)

Disadvantages of Suppositories

Inconvenient: Not favored by patients, especially children; some suppositories leak or are expelled.
Rectal absorption: Slow, irregular, and unpredictable.
Mucosal irritation: Caused by some drugs or bases.
Manufacturing/Storage costs: Higher than other drug forms.

Physiology of the Rectum

The rectum is ~15-20 cm in length, with 1.5-3 ml of fluids.
The pH is ~6.8.

Absorption of Drugs from the Rectum

50-70% of drugs absorbed directly into the bloodstream via hemorrhoidal veins, bypassing the liver's first-pass metabolism.
Route of absorption differs based on inferior vs. superior hemorrhoidal veins.

Factors Affecting Rectal Absorption

Physiological factors:
- Site of insertion.
- Route of absorption and circulation.
- Quantity of rectal fluid.
- Properties of rectal fluid.
- Contents of the rectum.
Physicochemical factors:
- Partition coefficient.
- Particle size.
- Nature of the base.

Properties of Rectal Fluids

Neutral pH (6.5-8).
No buffer capacity.

Contents of the Rectum (Empty vs. Full)

Empty rectum: Rapid drug absorption, rapid onset of action.
Full rectum: Slower drug absorption, delayed onset of action.

Physicochemical Factors Affecting Absorption

Drug solubility: Drugs highly soluble in the base will have slow release into rectal fluids, resulting in slow absorption; conversely, high solubility in rectal fluids leads to faster and more rapid absorption.
Particle size: Smaller particle size leads to faster dissolution and faster absorption.
Base properties: The ability of the base to melt, soften or dissolve will determine release rate of the drug leading to a faster or slower rate of drug action.
- Base interactions with the drug will impair or even prevent drug absorption.
- Bases which irritate mucous membranes will initiate a colonic response and bowel movement; incomplete drug release and absorption.

Ideal Suppository Bases

Non-toxic and non-irritant.
Inert and compatible with the drug.
Melts or softens at body temperature or dissolves in body fluids.
Readily releases the drug.
Easily molded and removed from the mold.
Stable to heating above the melting point.
Stable on storage.
Easy to handle.

Types of Suppository Bases

Fatty (Oleaginous/Hydrophobic): Cocoa butter, semi-synthetic fats. Melt at body temperature.
Hydrophilic (Water-Miscible/Water-Soluble): Glycerogelatin, PEG (Polyethylene Glycol), sorbitol, soap glycerin. Dissolve rather than melt at body temperature.

Cocoa Butter (A-Type)

Benefits: Solid at room temperature but melts at body temperature, miscible with many ingredients, non-irritating, non-toxic.
Drawbacks: Polymorphism (different crystalline forms depending on cooling rate).
Additional notes: Adherence to the mold; softening point may be too low for hot climates, requiring refrigeration during storage, melting point may be lowered by some drugs, or raised by others, rancidity on storage.

Cocoa Butter Substitutes (B-Type)

Benefits: Unaffected by overheating, low level of unsaturated fatty acids, good resistance to oxidation (preventing rancidity).
Drawbacks: More expensive, Brittle, can be challenging to handle, wrap, and use; greater risk of drug particles sedimenting during preparation, potentially causing localized irritation, requiring refrigeration for preparation and handling.

Hydrophilic Bases

Benefits: No laxative effect, less microbial contamination, melting points are typically above body temperature.
Drawbacks: Very hygroscopic (absorb water), requiring special packaging and storage, potentially lowers drug bioavailability by binding drugs in the base, potentially incompatible with certain drug types and/or packaging materials.

Problems in Formulation and Storage

Water: Should be avoided in suppositories, as it can increase the oxidation of fats and create bacterial/fungal growth, increase degradation rate of drugs, and cause reactions. If water evaporates, the drugs might recrystalize.
Hygroscopicity: Glycerin and PEG are hygroscopic.
Viscosity: Low viscosity may require additives for uniform dispersion of the drug.
Brittleness: Some substances can be brittle if cooled rapidly; additional components can prevent brittleness.

Suppository Evaluation and Quality Control

Appearance: Uniformity in size, shape, and color; no cracks or pits.
Weight uniformity: Compare individual weights to the average weight; no significant differences.
Drug content uniformity: Assesses the drug content in each suppository, comparing the results with the labelled drug content.
Liquefaction Time: Measures the time it takes for the suppository to fully melt or disperse in a constant temperature water bath.
Breaking Test: Measures the suppository's hardness and resistance to breaking.
Dissolution test: Measures the rate at which the drug dissolves.
Stability test: Assesses the long-term storage stability of the suppositories.

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Description

This quiz covers the essential information about suppositories and pessaries, including their types, uses, and advantages. Learn how these medicated forms function and their applications in treating various conditions. Test your knowledge on dosage and administration.