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What are suppositories?
- Solid dosage forms intended for insertion to the rectum, vaginal cavity or urethra
- Systemic or local effects
- Liquefies after insertion
How large are infant rectal suppositories?
How large are adult rectal suppositories?
What is the shape of rectal suppositories?
Cylindrical and tapered at one or both ends
What is the shape of vaginal suppositories?
What is the weight of most Vaginal suppositories?
What are vaginal suppositories also called?
What are urethral suppositories also called?
What is the shape of urethral suppositories?
What situations are rectal suppositories indicated for?
- Oral route not available
- The drug is not useful when applied orally
What are the disadvantages of rectal suppositories?
- Slow/incomplete absorption
- Intra/inter subject variation
- Local irritation
- Difficult to manufacture
- Long prep time
- Stringent storage conditions
What are rectal suppositories intended for?
What are rectal suppositories used for systemically?
- Tranquilizers and Sedatives
What are the physiological factors that affect suppository absorption?
What are the Physicochemical factors that affect suppository absorption?
- Particle size
- Partition coefficient
- Degree of ionization
What are the Physiochemical factors that affect suppository absorption?
- Melting point
Describe the Retum:
- 5-20 cm in length
- 2-3mL of mucous fluid prior to defecation
- No villi or microvilli
What three physiological issues can effect rectal suppository absorption?
- Tissue dehydration
- Colonic obstruction
When using a systemic suppository, what must be done prior to insertion?
Why is evacuation needed prior to use of systemic suppositories?
To increase absorption
How can evacuation be carried out?
Why is it advisable to keep the suppository in the lower part of the rectum?
To avoid the upper hemorrhoid vein, as it leads to portal circulation
What part of the rectum should patients be advised to put the suppository in and why?
- The lower part (nearest to anus)
- To avoid portal circulation
What percent of drug administered rectally goes directly into circulation?
What are the names of the Hemorrhoid veins?
Upper, middle and lower
What veins absorb rectal suppository drugs?
What happens to rectal drugs after absorption?
- Available for systemic effect
- Some pass portal circulation
- NO LIVER
What is the pH of rectal fluids?
What is the effective buffer capacity of the rectal fluids?
The rectal mucosa is preferentially permeable to what type of drugs?
How can rectal absorption be enhanced physiologically?
By changing the pH to one where the most drug is unionized
When selecting a base and determining the release of the drug from that base, what factors should you evaluate?
The Lipid water partition coefficient
A lipophilic drug will not release well in the hydrophilic rectal fluids if it is in what type of base?
What type of drugs can be used in suppository Fatty bases?
Water soluble salts
What type of base would you use for a lipophilic drug or a hydrophilic drug?
Water soluble base
What is the most common water soluble suppository base?
What is the rate limiting step suppository absorption?
- Partitioning of the drug from the suppository base
- NOT THE RATE AT WHICH THE DRUG CREATES A SOLUTION IN THE RECTAL FLUIDS
Will the rate of absorption continue to rise with higher rectal concentration?
What happens to the suppository base after insertion?
Melts or softens
What can affect the melting or softening of suppository bases?
What are the properties of an ideal suppository base (7)?
- Melts at 37.5 degrees C in presence of mucous secretiosn
- Easy to handle, doesn't break or melt
- Does not leak from rectum
- Stable in storage
- No meta-stable forms
What are the three classifications of suppository bases?
- Water soluble
- Water dispersible
Give two examples of oleaginous bases:
- Cocoa butter (Theobroma oil)
- Cocoa butter substitutes
Give two examples of Water soluble bases:
- Polyethylene glycol mixes
- Glycerinated gelatin
Give two examples of Water dispersible bases:
- Polyethylene glycol derivatives
- Cocoa butter substituted with surfactants
Describe the appearance of Cocoa butter:
yellowish white with chocolate scent
What is Cocoa butter composed of?
Glycerol esters of various FAs
What is the most widely used rectal suppository base?
Why is Cocoa butter so widely used?
It meets most of the requirements of an ideal base
What are the four main advantages of Cocoa butter?
- Melts at 30-36 degrees C
- Rapid melting and cooling
- Miscible with many drugs
What is the disadvantage of Cocoa butter/Oleaginous bases?
- Adherence to the mold
- Softening point to low for hot climates
- Poor water absorption
- Melting point lowered by soluble exipients
Describe how Water soluble bases work:
- Do not melt at body temperature
- Dissolve in body secretions
What is Glycerol suppository base B.P. made of?
- 14% gelatin
- 70% Glycerol
- QS 100% with water
What is glycerol-geltin base U.S.P. composed of?
- 20% gelatin
- 70% Glycerol
- QS 1005 with water
What type of base is Hygroscopic?
Glycerinated gelatin bases
What is Hygroscopic?
Tendency to absorb water
What are polyethylene glycols composed of?
Ethylene oxide and water of various lengths
What do the numerical designations after PEG indicate?
The average MW
What PEG MWs are clear colorless liquids?
300, 400 and 600
What PEG MWs are Semisolids?
What PEG MWs are wax-like white solids?
Over 1000, increasing hardness as MW increases
What is the melting point for most PEGs?
50 degrees C
If PEG bases melt at 50 degrees C, how is the drug released at body temperature?
You can blend different MW PEGs together to alter what characteristics?
- Melting point
- Physical Characteristics
- Dissolution rate
What is the iodine value?
The grams of iodine that react with 100 grams of Fat or unsaturated material
Why is the iodine value important?
- Correlates with:
- Decomposition by moisture, acids and oxygen
What is the solidification value for a suppository base?
The time it takes to solidify once cooled
What is the Melting range for a suppository base?
Initiation and endpoint of melting
What are the possible type of suppository base orgin?
Natural or synthetic
What is the acid value of a suppository base?
The mg of potassium hydroxide needed to neutralize the free acid in 1 gram of base
What relative Acid Value is good for suppositories?
Why is a low Acid Value good for suppository bases?
- Complicate formulation work
- React with ingredients
- Cause irritation
What is the water number for a suppository base?
The grams of water that can be incorporated into 100 grams of Fatty base
How can you increase the Water number of a fatty suppository base?
Addition of surfactants
What are the four methods of suppository manufacture?
- Hand Molding
- Compression molding
- Pour molding
- Automatic molding
What is the oldest and simplest method for making suppositories?
Describe Hand molding:
- Trituration of drug and base
- Rolled into a cylinder with steel blade spatula
What type of prescription could you use hand Molding for?
- Few suppositories needed
- Cocoa butter base
What is the process of Compression Method of suppository molding?
- Make a paste of the base and ingredients
- Compress in a die
What do you need to determine prior to compression molding?
The compressibility of the base in the dies
What is the most commonly used method for suppository production?
Describe the technique of pour molding:
- Base is melted
- Ingredients are added
- Suppositories are cooled
What is the output of a rotary automatic molding machine?
3,500-6,000 suppositories per hour
What type of suppositories need to be refrigerated?
Cocoa butter and glycerinated gelatin
What type of suppositories can be stored at room temperature?
What type of molds can suppositories be stored in?
Metal or Plastic
What are the advantages of disposable plastic suppository molds?
- Cheap to change mold shape
- No need to expensive molds or wrappings
- Eliminate the wrapping process
What are the five tests that should be performed on Suppositories?
- Melting range test
- Liquefaction test for rectal suppositories
- Disintegration test in-vitro
- Stability testing
- Breaking test