Podcast
Questions and Answers
What effect does a hygroscopic base have on mucosal membranes?
What effect does a hygroscopic base have on mucosal membranes?
Which base would provide a rapid drug release for a drug that is more soluble in water than in oil?
Which base would provide a rapid drug release for a drug that is more soluble in water than in oil?
What is an example of a slow-release agent used in suppositories?
What is an example of a slow-release agent used in suppositories?
Which of the following ingredients is used for deodorizing flatulence in suppositories?
Which of the following ingredients is used for deodorizing flatulence in suppositories?
Signup and view all the answers
Which component of a suppository base is hygroscopic?
Which component of a suppository base is hygroscopic?
Signup and view all the answers
How does the volume of a suppository determine its formulation?
How does the volume of a suppository determine its formulation?
Signup and view all the answers
In an antiemetic suppository, which ingredient acts as a suspending aid?
In an antiemetic suppository, which ingredient acts as a suspending aid?
Signup and view all the answers
Which formulation characteristic is important for the cocoa butter-base suppository?
Which formulation characteristic is important for the cocoa butter-base suppository?
Signup and view all the answers
What is one advantage of using suppositories for drug delivery?
What is one advantage of using suppositories for drug delivery?
Signup and view all the answers
Which of the following is a disadvantage of rectal drug delivery?
Which of the following is a disadvantage of rectal drug delivery?
Signup and view all the answers
What is a common issue that may affect vaginal absorption of medications administered via pessaries?
What is a common issue that may affect vaginal absorption of medications administered via pessaries?
Signup and view all the answers
Suppositories avoid certain issues associated with oral administration. Which of the following is NOT one of them?
Suppositories avoid certain issues associated with oral administration. Which of the following is NOT one of them?
Signup and view all the answers
How does the first pass metabolism affect the effectiveness of rectally administered drugs?
How does the first pass metabolism affect the effectiveness of rectally administered drugs?
Signup and view all the answers
What might impede the self-administration of suppositories for patients with arthritis?
What might impede the self-administration of suppositories for patients with arthritis?
Signup and view all the answers
What is a reason that rectal absorption can be erratic?
What is a reason that rectal absorption can be erratic?
Signup and view all the answers
Which method can help facilitate the insertion of a rectal suppository?
Which method can help facilitate the insertion of a rectal suppository?
Signup and view all the answers
Which vein is responsible for draining the superior rectal vein into the hepatic portal vein?
Which vein is responsible for draining the superior rectal vein into the hepatic portal vein?
Signup and view all the answers
What is the primary factor that can significantly affect rectal drug absorption?
What is the primary factor that can significantly affect rectal drug absorption?
Signup and view all the answers
Which type of drug absorption occurs with hydrophobic base suppositories?
Which type of drug absorption occurs with hydrophobic base suppositories?
Signup and view all the answers
What characteristic of a suppository base can make it hygroscopic?
What characteristic of a suppository base can make it hygroscopic?
Signup and view all the answers
Which statement is true regarding the middle and inferior rectal veins?
Which statement is true regarding the middle and inferior rectal veins?
Signup and view all the answers
What is a notable feature of glycogelatin as a suppository base?
What is a notable feature of glycogelatin as a suppository base?
Signup and view all the answers
Which factor does NOT typically affect rectal absorption?
Which factor does NOT typically affect rectal absorption?
Signup and view all the answers
What is the relationship between the superior rectal vein and first pass hepatic metabolism?
What is the relationship between the superior rectal vein and first pass hepatic metabolism?
Signup and view all the answers
Which of the following can enhance drug solubility for rectal absorption?
Which of the following can enhance drug solubility for rectal absorption?
Signup and view all the answers
What must be adjusted when formulating suppositories that contain more than 5% w/w drug?
What must be adjusted when formulating suppositories that contain more than 5% w/w drug?
Signup and view all the answers
If a drug with a 'displacement value' of 2.0 displaces how much base when 1.0 g of the drug is used?
If a drug with a 'displacement value' of 2.0 displaces how much base when 1.0 g of the drug is used?
Signup and view all the answers
What is the formula for calculating the displacement value (DV) of a drug?
What is the formula for calculating the displacement value (DV) of a drug?
Signup and view all the answers
Which of the following drugs has the highest displacement value?
Which of the following drugs has the highest displacement value?
Signup and view all the answers
If a drug has a displacement value of 1.5 when calculated with cocoa butter, what will its DV be with a PEG base?
If a drug has a displacement value of 1.5 when calculated with cocoa butter, what will its DV be with a PEG base?
Signup and view all the answers
What is the density of cocoa butter used in the displacement value calculations?
What is the density of cocoa butter used in the displacement value calculations?
Signup and view all the answers
What weight of base is needed when preparing a suppository containing 1.0 g of drug, considering its displacement?
What weight of base is needed when preparing a suppository containing 1.0 g of drug, considering its displacement?
Signup and view all the answers
Which factor influences the displacement value of a drug?
Which factor influences the displacement value of a drug?
Signup and view all the answers
What is the purpose of moistening powder with mineral oil before blending with melted base?
What is the purpose of moistening powder with mineral oil before blending with melted base?
Signup and view all the answers
What should be done with suppositories before they have completely hardened?
What should be done with suppositories before they have completely hardened?
Signup and view all the answers
Which of the following is a common ingredient in hormone replacement pessaries?
Which of the following is a common ingredient in hormone replacement pessaries?
Signup and view all the answers
What is the correct density of glycerinated gelatin used in formulary calculations?
What is the correct density of glycerinated gelatin used in formulary calculations?
Signup and view all the answers
How much base is required for a pessary containing 500 mg metronidazole?
How much base is required for a pessary containing 500 mg metronidazole?
Signup and view all the answers
Which stage of the suppository preparation involves minimizing handling to prevent melting?
Which stage of the suppository preparation involves minimizing handling to prevent melting?
Signup and view all the answers
What is the purpose of allowing slow cooling and congealing of the melted mixture?
What is the purpose of allowing slow cooling and congealing of the melted mixture?
Signup and view all the answers
In what form are suppositories and pessaries typically delivered?
In what form are suppositories and pessaries typically delivered?
Signup and view all the answers
Study Notes
Rectal blood circulation
- Superior rectal vein drains into the hepatic portal vein
- The portal vein leads to the “first-pass hepatic metabolism” of drugs
- Middle and inferior rectal veins drain directly into general systemic circulation
- Little “first-pass hepatic metabolism” of the drug occurs in the middle and inferior rectal veins
Rectal Drug Absorption
- Hydrophobic base suppositories melt into a very thin layer of mucous that allows the drug to be passively diffused
- Hydrophilic base suppositories dissolve and mix with the mucous layer where the drug is then passively diffused
Factors affecting rectal absorption
- The type of base used
- The type of drug
- The solubility of the drug in the vehicle (surfactant may be needed)
- The concentration of the drug
- The particle size of the drug
Hydrophilic Base: Glycogelatin
- Glycogelatin is made up of: Glycerin + Gelatin + Water (e.g. 70:20:10)
- It is not used as much as cocoa butter or PEG bases
- Glycogelatin is good for laxative suppositories
- Used for vaginal suppositories (e.g.paracetamol, morphine)
- It can also deliver: anti-inflammatories, anti-emetics and anti-nausea drugs, sedatives/tranquilisers, antihaemorrhoidals, hormones, antibacterials, antifungals, contraceptives
Advantages of suppositories and pessaries
- Ease of administration by a professional or by the user
- Easy to remove or flush out if necessary
- Useful for young children and the elderly
- Provides rapid, targeted drug delivery when systemic delivery is unsuitable
- Limits systemic exposure to the drug
- Partially avoids first-pass intestinal and hepatic metabolism allowing > 30% of the dose to reach systemic circulation unchanged
- Allows for large doses to be delivered
Advantages of suppositories and pessaries (cont’d)
- Can be used in unconscious and disabled patients
- Can be used in infants and young children
- Avoids problems with oral administration:
- Taste or smell
- Drug degradation in the stomach acid
- Nausea and vomiting
- Pre-surgical need to keep stomach empty
Disadvantages of suppositories and pessaries
- Drug absorption is slower vs. oral or IV administration
- Percentage absorption is variable and unpredictable
- Not suitable for drugs with a narrow therapeutic range
- Potential for mucosal irritation
- Potential for triggering defecation and loss of product from the rectum
- Diarrhoea and GI disease reduce absorption
Disadvantages of suppositories and pessaries (cont’d)
- Menstruation can affect vaginal absorption
- Leakage of melted product
- Can be difficult for arthritics to self-administer
- Cost of production is high
Drug release rates from different bases
- Oily bases promote slow drug release for oil-soluble drugs, and rapid release for water-soluble drugs
- Water-miscible bases produce a moderate drug release for oil-soluble drugs, and slow to fast release for water-soluble drugs
Preparing cocoa butter suppositories
- Wash hands, wear rubber or vinyl gloves
- Remove the suppository from its wrapping
- Moisten the suppository if necessary
- Lubricate the mould if required
- Pour the stirred melt into the mould quickly in one movement
- Allow the suppository to cool and congeal slowly
- Trim excess if needed
- Carefully remove the suppository from the mould
- Wrap and put into a container
- Label and dispense
Formulating suppositories
- Suppositories have a fixed volume determined by the volume of the mould
- When formulating suppositories with >5% w/w drug, we need to allow for the volume of the base “displaced” by the drug and reduce the quantity of the base in the mixture accordingly
Displacement Values
- Drugs have a “displacement value” (DV) or “density factor”
- The DV is the number of grams of active ingredient that displaces 1 gram of base
- DV = Density of drug / density of cocoa butter
- Reference books usually list DVs relative to cocoa butter base which has a density of 0.9 g/mL
Examples of DVs
- Boric acid: 1.5
- Codeine phosphate: 1.1
- Hydrocortisone: 1.5
- Morphine HCl: 1.6
- Paracetamol: 1.5
- Phenobarbital: 1.2
- Zinc oxide: 4.0
Displacement Values relative to PEG bases
- PEG bases have a density of 1.09 g/mL (about 1.20 times the density of cocoa butter)
- To calculate the DV relative to PEG, divide the DV relative to cocoa butter by 1.2
- For example, boric acid DV vs. cocoa butter 1.5, DV vs. PEG 1.5 / 1.2 = 1.25
Examples of Vaginal Pessaries
- Hormone replacement pessary: Progesterone 200 mg (active), Silicon dioxide 35 mg (suspending aid), Polyethylene glycol base qs (base)
- Antibiotic for vaginal vaginosis: Metronidazole 500 mg (active), Glycerinated gelatin base qs (base)
Summary
- Suppositories and pessaries are solid dosage forms designed to deliver drugs to the rectum or vagina.
- Some suppositories are designed to deliver drugs locally, while others are designed to deliver drugs systemically.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
Explore the intricacies of rectal blood circulation and drug absorption through this quiz. Understand the differences in absorption based on drug solubility and base types, including hydrophilic and hydrophobic suppositories. Test your knowledge on the factors affecting these processes.
