Routes of Administration - Oral Flashcards
1
Q
Absorbition of oral drugs
A
- Movement of drug from the site of administration to bloodstream
- It’s bioavailability
2
Q
Protiens in phospholipid membrane
A
- Embedded in the phospholipid membrane
- Srranged related to solubility
3
Q
Transcellular
A
- Passive diffusion that is mediated by carrier protiens and active transport
4
Q
Paracellular
A
Through the tight junction the cell membrane
5
Q
Gastic emptying
A
- Faster onset if gastric emptying is higher
- Stomach pressure remains constant until 1L of food is ingested
- Smooth muscle exibits plasticity due to unchanged pressure
- Most vigorous peristalsis and mixing occurs near the pylorus valve while it is closed
6
Q
Gastric emptying
Chyme
A
- Delivered in small amounts (about 3 mL) to the duodenum
- Forced backward into the stomach for further mixing
7
Q
Factors that effect Gastric emptying
Meal volume
A
Gastric emptying is a simple exponential function of the volume of a meal - larger the meal the faster the gatric emptying
8
Q
Factors that effect Gastric emptying
Meal composition
A
- Stomach empties liquids faster than solids
- Carbohydrate-rich chyme quickly moves through duodenum
- Fat-laden chyme is digested more slowly causing food to remain in the stomach longer
9
Q
Factors that effect Gastric emptying
pH of contents
A
- Acids delays gastric emptying
- pH of chyme in the small intestine of (< 3.5 – 4) will activate reflexes to inhibit stomach emptying until duodenal chyme can be neutralised by pancreatic and other secretions
- Careful of antacids (e.g. aluminium hydroxide gel) that raise the pH of stomach contents (gaviscon)
10
Q
Gastric emptying rate
A
Speed with which substances leave the stomach after ingestion
11
Q
Absorbtion in deuodeum
A
- The duodenum has the greatest capacity for the absorption of drugs from the GI tract
- Rapidly reaches the stomach
- Eventually, the stomach empties its contents into the small intestine
12
Q
What will a delay in gastic emptying cause?
A
- Delay in the gastric emptying time will slow the rate and possibly the extent of drug absorption
13
Q
What times should Asprin be taken?
A
- Take with food
- May irritate the gastric mucosa during prolonged
14
Q
What time should Amoxicillin be taken
A
- Take before food
- Improve absorption as food can affect absorption
- Unstable in acid and will decompose if stomach emptying is delayed
15
Q
Rate-limiting step
A
Slowest step in the series, which controls the overall rate and extent of appearance of the intact drug in the systemic circulation
16
Q
Types of rate limiting factors
A
- Drug release from dosage form – disintegrate
- Gastric emptying
- Dissolution – high log P hardly dissolves
- Permeability – low log P is hardly absorbed
- Metabolism – including metabolism in the liver
17
Q
Tablet formulation
A
- Disintergrating tablets
- Chewable tablets
- Effervescent tablets
- Lozenges
- Sublingual tablets
- Buccal tablet
18
Q
Advantages of tablets
A
- Ease of administration and patient acceptance
Swallowing - Chewable formulations
- Elegance
- Convenient handling/compactness
- Accurate dosage
- Chemical and physical stability
- Different to tamper with
- Low cost of manufacturing, packaging, shipping
19
Q
Steps of disintegration
A
- Disintegration into granules
- Deaggregation of granules forming primary drug particles
- Drug in solution
20
Q
Types of capsule coating
A
- Gelatin
- Alternative polymers
- Soft capsules
Gelatin - Vegetarian option
21
Q
Advsantages of capsules
Patient complience
A
- Easier to swallow as itis smooth & slippery
- Tasteless and odourless which eliminate all contact between drug and mouth)
- Can be opened up
- Contents sprinkled on food
- Clear, high-gloss coloured film that can be printed on
22
Q
Advantages of capsule
Drug delivery
A
- Fast acting
- Breakdown of capsule shell occurs readily ≈ disintegration of tablet
- Beads/pellets/granules in addition to dry powder fills
- A mixture of beads with different release rates
- Other dosage forms in a capsule
- Mini tablets and liquids
23
Q
Capsule dissolution
A
- Hard gelatin capsules containing only hydrophobic drug particles
- Hard gelatin capsules containing hydrophobic drug particles and hydrophilic diluent particles
- In GI fluids, hard gelatin capsule shell dissolves, thereby exposing contents of fluids
- Contents remain as capsule-shaped plug. Hydrophobic nature of contents impedes penetration of GI fluids
- Particles of hydrophilic diluent dissolve in GI fluids leaving a porous mass of drug
Dissolution of drug occurs only from surface of plug-shaped mass. Relatively low rate of dissolution
GI fluids can penetrate porous mass
Effective surface area of drug and hence dissolution rate is increased
24
Q
Liquid oral dosage form
A
- Rapid and complete, greater bioavailability compared to other oral dosage forms
25
liquid oral dosage suspension
- Absorption may well be dissolution-limited
Suspension of a finely divided powder will maximize the potential for rapid dissolution
- Secondary dissolution to solution
26
Sublingual
Application to the membranes of either the floor of the mouth or the underside of the tongue and entry into systemic circulation following absorption
27
Buccal
Application to the lining of the cheek – entry into the systemic circulation following absorption
28
Keratinised mucosa
Hard palate, gingiva and tongue
29
Non-keratinised mucosa
Floor of the mouth, the soft palate, the lips and the cheek
30
Advantages of Sublingual dosage form
- Relatively permeable
- Rapid absorption
- Unsuitable for retentive system
- Ideal for rapid onset of action
- Sprays or fast-dissolving tablets
31
Advantages of Buccal dosage form
- Relatively less permeable
- Not rapid absorption
- Suitable for retentive system
- Ideal for sustained release
- Adhesive tablets or patches
