37 Questions
What is the structure of the rectum in terms of length?
Approximately 12 cm long
Where does the anus drain to?
Middle and inferior haemorrhoidal veins
What is the pH of the rectum?
Neutral
Which conditions can be treated using the rectal route?
Haemorrhoids (piles)
Why is access to colon a reason for using the rectal route?
To manage inflammatory bowel diseases
Which blood vessels does the top of the rectum drain to?
Superior haemorrhoidal vein
Which type of vaginal product is specifically mentioned to need an applicator for administration?
Tampons
What is the primary issue raised regarding the use of creams and gels as vaginal products?
The possibility of them being very messy in application
Which type of vaginal product is described as generally antiseptic/cleansing and might be considered very messy to use?
Solutions (Douches)
Among the types of vaginal products listed, which one is specifically made from silicon and meant to remain in place for several days or weeks?
Intra-vaginal rings (IVRs)
What distinguishes medicated tampons from ordinary menstrual tampons in their use as vaginal products?
They release drugs for therapeutic effects
What determines the formulation type selected for rectal and vaginal products?
The intended route of administration and site of action
What is the approximate weight of a suppository suitable for babies and small children?
1 g
Which type of suppository base melts at or just below body temperature?
Theobroma Oil
What is the primary reason for adding a wax to rise the melting point of suppository bases?
To raise the melting point
Which suppository base is known for being polymorphic and producing an unstable form when heated above 36°C?
Theobroma Oil
What is the function of water in Polyethylene glycol (PEG) as a suppository base?
To act as a cosolvent
Which type of gelatin is cationic and may require care with charged drugs when used in a suppository base?
Type A gelatin
What does the standard Glycerin-gelatin mixture for suppositories consist of?
14 %w/w gelatin, 70 %w/w glycerin, 16 %w/w water
What is the purpose of adding liquid or soluble drugs to Theobroma Oil as a suppository base?
To lower the melting point
What should be considered when selecting a Witepsol base for suppositories?
The viscosity of the base
What is the primary reason for using Plastic moulds for modern suppositories?
To improve dosage accuracy
What is the weight of drug X in a 1g size suppository containing 20%w/w drug X and 80%w/w base?
0.20g
What is the displacement value (DV) of drug X in the suppository?
0.22
Which type of rectal preparation involves a dispersion of gas in a liquid stabilized by surfactants?
Rectal foams
What is the pH of the vaginal environment?
3.8 - 4.5
Which type of rectal preparation is used for diagnostic purposes such as barium enema?
Rectal solutions and suspensions
What is the length of the vaginal tract along the posterior wall?
7.5 to 9 cm
What is the displacement value of paracetamol in the manufacture of suppositories?
1.5
What is the theoretical amount of suppository base required to make 9 x 2 g suppositories containing paracetamol 500 mg?
18 g
What is the final formula for making 6 x 1 g suppositories containing aminophylline 130 mg?
Aminophylline 1.17 g, Suppository base 8.1 g
What is the displacement value of metronidazole in the manufacture of suppositories?
1.7
What is the final formula for making 6 x 2 g suppositories containing metronidazole 510 mg?
Metronidazole 4.59 g, Suppository base 15.3 g
What happens if you have two drugs in the manufacture of suppositories?
Calculate the displacement due to each drug individually and subtract the total from the theoretical value
How are displacement values calculated in the manufacture of suppositories?
By comparing weights of suppositories made from pure base and a known mix of drug and base
What is the purpose of making excess suppositories in the manufacture of suppositories?
To ensure that there is enough material in case of errors or losses during manufacturing
What is the maximum number of suppositories that can be manufactured per hour using a heated mixer and a moulding machine?
25,000
Study Notes
Rectal and Vaginal Physiology
- Rectal physiology:
- Function: storage of faecal waste before evacuation
- Structure: rectum is a straight tube, approximately 12 cm long, joined to the sigmoid colon at the top and anus at the base
- pH: essentially neutral, with low levels of fluid and some mucus
- Blood supply: top of the rectum drains to the superior haemorrhoidal vein, eventually to the hepatic portal vein, and the base of the rectum drains to the middle and inferior haemorrhoidal veins, eventually to the inferior vena cava
- Vaginal physiology:
- Structure: dilated tube, approximately 6-7.5 cm along the anterior wall and 9 cm along the posterior wall, joined to the uterus at the top
- Mucosal surface with some lymphatic tissue, well-perfused
- pH: slightly acid, pH 3.8-4.5, with low levels of fluid
Rectal and Vaginal Therapy
- Why use the rectal route:
- Local treatment: haemorrhoids, infections, and malignancy
- Access to colon: laxatives, chronic inflammatory diseases, and hormone replacement therapy
- Systemic use: good blood supply, potential for immunisation
- Why use the vaginal route:
- Local treatment: infections, hormone replacement therapy, and malignancy
- Access to cervix: induction/maintenance of labour, and uterine therapy
Rectal Products
- Types of rectal products:
- Suppositories
- Rectal capsules
- Rectal solutions and suspensions (enemas)
- Powders for reconstitution
- Semi-solid preparations
- Foams
- Suppositories:
- Size: 1-4 g, depending on age and indication
- Design: tapered, aids insertion and retention
- Properties of an ideal base:
- Melts at or just below body temperature
- Dissolves in rectal fluid
- Non-toxic, non-irritating, and therapeutically inert
- Compatible with all drugs, chemically inert
- Physically and chemically stable
- Easy to work with
- Suppository bases:
- Theobroma Oil (Cocoa butter)
- Synthetic Triglycerides (e.g. Witepsol, Suppocire)
- Glycerin-gelatin mixtures
- Polyethylene glycol (PEG)
- Rectal capsules:
- Soft gelatin capsules with a non-aqueous liquid fill
- Drug dissolves or is suspended in the liquid fill
- Capsule shell dissolves in rectal fluid, releasing the drug
- Rectal solutions and suspensions (enemas):
- Liquid preparations, volume 2.5 mL to 2000 mL
- Generally supplied as a reservoir with a long nozzle
- Local treatment of rectum, access to colon, and colonic irrigation
Vaginal Products
- Types of vaginal products:
- Pessaries
- Vaginal suppositories
- Vaginal tablets
- Vaginal capsules
- Creams and gels
- Solutions (douches)
- Foams
- Intra-vaginal rings (IVRs)
- Tampons
- Pessaries:
- Size: larger than rectal suppositories (up to 8 g)
- Formulation issues: similar to rectal suppositories
- Vaginal tablets:
- Size: wider range than oral tablets
- Formulation issues: similar to oral tablets
- Creams and gels:
- Must be water-based to avoid stinging
- Formulation issues: similar to other creams and gels
- May need up to 5 g of cream (large volume)
- Solutions (douches):
- Generally antiseptic or cleansing
- Volume: up to 250 mL
- Formulation issues: similar to other non-oral solutions
- Intra-vaginal rings (IVRs):
- Ring-shaped, made from silicon
- Inserted at the top of the vagina, remain in place for several days or weeks
- Drug released from the surface of the IVR, dissolves in vaginal fluid, and diffuses to the cell surface
Manufacturing of Suppositories
- Displacement values:
- Define the amount of base displaced by a given amount of drug
- Calculate the displacement value (DV) by comparing the weights of suppositories made from pure base and a known mix of drug and base
- DVs are listed in textbooks and the practical manual
- Manufacturing process:
- Dispensing/lab scale: use metal or plastic moulds, fill by volume, and seal the moulds
- Production scale: use heated mixers, fill by volume, and seal the moulds
- Displacement values - examples:
- Calculate the displacement value (DV) of a drug
- Calculate the amount of base displaced by a given amount of drug
- Calculate the final formula for a suppository preparation
Learn about rectal and vaginal physiology, the rationale of rectal and vaginal therapy, the types of products used for rectal and vaginal dosing, and formulation and production issues. Explore the function and structure of rectal physiology.
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