Rectal and Vaginal Dosage forms Flashcards
What are advantages of rectal dosage form?
- Patients that cannot swallow
- GI tract irritant drugs or unstable drugs
- Treatment of diseases of the lower parts of Gi tract
- Once daily use
- Local & systemic effect
- Avoid first pass metabolism
What are disadvantages of rectal dosage form?
- Poor compliance
- Discomfort and leakage
- Variation of absorption
- irritation of mucous membranes
- Upward movement of suppository from local site can increase first-pass metabolism
What is the following for Rectal suppositories:
Weight
Local action
Systemic action
Weight: 1g (baby), 2g (adult), 4-5g (rectal rocket)
Local action: hemorrhoids, laxative
Systemic action: antiemetics, analgesics, hormones
Vaginal Inserts
Weight:
Bases:
Uses:
Weight: 3-5g
Bases: water-soluble or water-miscible (PEG)
Uses:
- Contraceptive
- Gynecological ailments
- Antiseptics in feminine hygeine
Urethral inserts
Diameter:
Length: male + female
Weight male + female
Uses:
Diameter: 3-6mm
Length:
- Male: 125 mm
- Female: 50 mm
Weight:
- Male: 4g
- Female 2g
Uses:
- severe ED
- Antibacterial
- Local anesthetic to prepare for examination
What is the composition of suppositories
- Active ingredient
- Additives
- Suppository bases
What are the 2 hydrophobic bases and the 2 hydrophilic base?
Hydrophobic
1. Cocoa butter
2. Synthetic/semi-synthetic fatty bases (witepsol, fattibase)
Hydrophilic base
1. Glycerinated gelatin
2. Polyethylene glycols PEG
Advantages of Cocoa butter
- Melts readily on warming
- Compatible with many ingredients
- Non-irritating
Disadvantages of Cocoa butter (4)
- polymorphism when heated above
- Should be refrigerated
- No tolerance to oxidation
- Hydrophobic (poor water absorbing capacity)
Advantages of semi-synthetic fatty bases
- No polymorphism
- Tolerance to oxidation
- Improved drug release and bioavailability (with presence of surfactants)
Disadvantages of semi-synthetic fatty bases.
- Need to be stored in the refrigerator
- Become brittle if cooled quickly
- They may have dehydrating effect
Disadvantages of glycerinated Gelatin bases
- Have a physiological action (osmotic laxative effect)
- Can lead to dehydration of the mucosa
- mainly used vaginally
Advantages and disadvantages of PEGs
Advantages
- do not require refrigerator
- do not melt at body temperature
Disadvantages
- Hygroscopic: mucosa irritation
- Contract significantly when cooling
Explain drug release and absorption in the rectal cavity.
Explain blood supply in the: inferior & superior rectal vein
- lower buffer capacity (need addatives)
Inferior rectal vein: bypass the liver
Superior rectal vein: carries drug to liver
Which type of Base melts/dissolves the quickest
Cocoa butter
