Pharmaceutics: Suppository Drug Absorption
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Questions and Answers

What is the main component of lubricant?

  • Beeswax
  • Surfactants
  • Cocoa butter
  • Aqueous solution of SLS (correct)

    • How many polymorphic forms does cocoa butter exist in?

  • 2
  • 4 (correct)
  • 3
  • 5

    • What is the melting point of the stable beta polymorph of cocoa butter?

  • 28oC
  • 17.3oC
  • 34-35oC (correct)
  • 20oC

    • What happens when cocoa butter is melted at about 36oC and allowed to solidify slowly?

    <p>The stable beta polymorph is formed</p> Signup and view all the answers

    What is the effect of adding certain drugs, such as volatile oils, to cocoa butter?

    <p>The melting point is decreased</p> Signup and view all the answers

    What is added to cocoa butter to increase its absorptive capacity for water?

    <p>Surfactants such as cholesterol</p> Signup and view all the answers

    What is the purpose of adding 3% to 5% of beeswax or spermaceti to cocoa butter?

    <p>To raise the melting point of cocoa butter</p> Signup and view all the answers

    What is a characteristic of cocoa butter depending on its source?

    <p>Consistency, odor, and color may vary</p> Signup and view all the answers

    What happens to a dissolved drug in a suppository?

    <p>It diffuses out towards the rectal membrane</p> Signup and view all the answers

    What happens to a suspended drug in a suppository?

    <p>It leaves the vehicle, precipitates, and then dissolves and diffuses out towards the rectal membrane</p> Signup and view all the answers

    What is a factor that affects the bioavailability of a drug in the rectum?

    <p>The properties of the rectal fluid</p> Signup and view all the answers

    What is typically the volume of available fluid in the rectum under physiological conditions?

    <p>3 ml</p> Signup and view all the answers

    What happens to the volume of available fluid in the rectum under non-physiological conditions?

    <p>It increases</p> Signup and view all the answers

    What is the effect of increased fluid volume in the rectum on the absorption of slightly soluble drugs?

    <p>It makes the absorption rate dissolution-rate limited</p> Signup and view all the answers

    What is the main composition of semi or fully synthetic triglycerides?

    <p>Mixture of mono, di- and tri- glycerides of saturated fatty acids (C10-C18)</p> Signup and view all the answers

    What is the typical iodine number of synthetic fats?

    <p>&lt; 3</p> Signup and view all the answers

    What is the advantage of synthetic fats over cocoa butter in terms of melting range?

    <p>The melting range is usually about 3oC higher than that of cocoa butter.</p> Signup and view all the answers

    What is the typical acid content of synthetic fats?

    <p>mostly &lt; 0.5</p> Signup and view all the answers

    What does a higher hydroxyl number indicate about a fatty base?

    <p>It can absorb more water and is less suitable for drugs that degrade easily by hydrolysis.</p> Signup and view all the answers

    What is the typical melting range of cocoa butter?

    <p>31-34oC</p> Signup and view all the answers

    What is the source of fatty bases?

    <p>Entirely natural, synthetic, and modified natural</p> Signup and view all the answers

    What is an example of physical and chemical incompatibilities with additives in fatty bases?

    <p>Preservatives</p> Signup and view all the answers

    What is the term for the amount of esters that can be hydrolyzed and turned into soap in fatty bases?

    <p>Saponification value</p> Signup and view all the answers

    What is the range of saponification values in fatty bases?

    <p>200 to 245</p> Signup and view all the answers

    What does the iodine value of fatty bases indicate?

    <p>The possibility of decomposition by oxygen</p> Signup and view all the answers

    What is the preferred iodine value in fatty bases?

    <p>Less than 7</p> Signup and view all the answers

    What are the wetting and emulsifying properties of fatty bases used for?

    <p>To create a stable emulsion</p> Signup and view all the answers

    What is the term for the temperature at which a fatty base is completely melted?

    <p>Melting range</p> Signup and view all the answers

    What is the primary mechanism by which the abdominal organs exert pressure on a suppository in the rectum?

    <p>By simply pressing on the rectum when the body is in an upright position</p> Signup and view all the answers

    What is the primary intention of a suppository?

    <p>To produce a systemic effect, local action, or mechanical effect</p> Signup and view all the answers

    What is the typical melting temperature of cocoa butter, a base used in suppository preparation?

    <p>At body temperature</p> Signup and view all the answers

    What is the primary consideration for the pharmacist when formulating suppositories?

    <p>The requirement of the vehicle and the shape, content, and weight of the suppository</p> Signup and view all the answers

    What is the typical range of the weight of a suppository?

    <p>1 to 4 grams</p> Signup and view all the answers

    What is the desirable property of a vehicle used in suppository preparation?

    <p>It should melt or dissolve in the rectum and mix with rectal fluid at around 34-36°C</p> Signup and view all the answers

    What is the primary mechanism by which motility of the rectal muscle affects suppository absorption?

    <p>Through the increased pressure on the suppository, promoting spreading and absorption</p> Signup and view all the answers

    What is the primary function of glycerinated gelatin as a base in suppository preparation?

    <p>It helps to dissolve the active ingredient</p> Signup and view all the answers

    Study Notes

    Rectal Drug Absorption

    • Drug dissolved in suppository diffuses out towards rectal membrane, followed by absorption
    • Suspended drug leaves vehicle, precipitates or separates due to gravity and motility, then dissolves and diffuses before being absorbed

    Physiological Factors Affecting Rectal Drug Absorption

    • Properties of rectal fluid:
      • Composition, viscosity, pH, and surface tension affect drug bioavailability
    • Content of the rectum:
      • Rectum is usually empty, but fecal contents from higher parts of the colon can affect absorption
    • Enzymes:
      • Rectum has no active esterases or peptidases, unlike the GIT
    • Volume of available fluids:
      • Typical volume of available fluid in the rectum is ~3 ml spread on a layer of ~100 µm thick
      • Volume increases under non-physiological conditions, affecting absorption of slightly soluble drugs
    • Motility of the rectal wall:
      • Rectal wall exerts pressure on suppository, promoting spreading and absorption

    Suppositories

    • Intended to produce local action, systemic effect, or mechanical effect to facilitate emptying the lower bowel
    • Prepared in various weights, sizes, and shapes according to intended use
    • Drug is incorporated into a base, such as cocoa butter, glycerinated gelatin, or PEG

    Formulation of Suppositories

    • Pharmacist must consider shape, content, weight, and vehicle requirements
    • Shape: cylindrical, conical, or torpedo
    • Content: ranges from 0.1 to 40% w/w
    • Weight: ranges from 1 to 4 grams
    • Vehicle requirements:
      • Melts or dissolves in the rectum and mixes with rectal fluid at ~34-36°C
      • Melting range should be low enough to give rapid solidification and avoid drug precipitation

    Fatty Bases

    • Specifications:
      • Origin and chemical composition (entirely natural, synthetic, or modified natural)
      • Physical and chemical incompatibilities with additives (preservatives, antioxidants, emulsifiers)
    • Melting range
    • Solidification point
    • Saponification value
    • Iodine value
    • Wetting and emulsifying properties
    • Water number
    • Acid value

    Polymorphism of Cocoa Butter

    • Exists in four polymorphic forms: α, β, β', and γ
    • β polymorph is stable, while α, γ, and β' are unstable and revert to β
    • To minimize formation of unstable forms, heat only briefly and below 36°C

    Lowering of Melting Point

    • Caused by addition of certain drugs (volatile oils, phenol, chloral hydrate)
    • Can be raised back to desired range by adding beeswax or spermaceti (3-5% w/w)

    Synthetic Fats vs Cocoa Butter

    • Advantages of synthetic fats:
      • No polymorphism
      • Contain mainly saturated acids (iodine number < 3)
      • Melting range is usually about 3°C higher
      • Acid content is lower (mostly < 0.5)
      • Hydroxyl number (5-30)

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    Description

    This quiz covers the process of drug absorption through suppositories, including the role of diffusion and physiological factors affecting rectal drug absorption.

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