L32 - Absorption: Sublingual, Buccal And Rectal Drug Delivery Flashcards by Mia Espino

What is topical drug delivery to the mouth used to treat? (3)

ulcers
fungal infections
periodontal disease

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What are the different transmucosal delivery? (2)

sublingual
buccal

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What has a signigicant effect on drug absorption?

They physiology of the mouth

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What is the lining of the mouth?

Oral mucosa
(Buccal, sublingual, gingival, labial, palatal mucosae)
200cm2 (buccal + sublingual)

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What is the structure of the oral mucosa? (4)

epithelium (membrane coating granules from prickle cells)
basement membrane
lamina propria
sub-mucosa

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What are the different mucosal types? (3)

masticatory (gingival, palatal tissue)
lining (buccal, sublingual tissue)
specialsied (dorsal tongue)

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What is the structure, thickness (mcm), permeability, residence time and % area of masticatory gingival tissue? (5)

K
200mcm
poor
intermediate
50%

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What is the structure, thickness (mcm), permeability, residence time and % area of masticatory palatal tissue? (5)

K
250mcm
poor
very good
50%

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What is the structure, thickness (mcm), permeability, residence time and % area of lining buccal tissue? (5)

NK
500-600
intermediate
intermediate
30&

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What is the structure, thickness (mcm), permeability, residence time and % area of lining sublingual tissue?

NK
100-200
very good
poor
30%

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What is the structure, thickness (mcm), permeability, residence time and % area of specialised dorsal tongue tissue?

K/NK
n/a
n/a
20%

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What goes through transcellularly?

Small lipophilic drugs
- passive diffusion, epithelial thickness affects flux

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What goes through paracellularly?

Small hydrophilic drugs
- epithelial thickness affects flux
- intracellular lipids (MCGs)

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What is the pH of oral cavity?

Approx 5.6-7.6
Log P values generally 1-5

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What is saliva composed of?

Water + mucus, electrolytes and enzymes
- 0.5-2.0 L per day, 1.1 mL present

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What are degraders in the saliva? (5)

Aminopeptidases,
carboxypeptidases
esterases
carbohydrases
lysosymes

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What is saliva wash out?

Aid or hinder drug asborption

What type of barrier is mucus? (2)

physical (30.400mcm)
chemical (-ve charge)

What is blood supply like in the mouth? (2)

good blood fow (Buccal = 2.4 ml min-1 cm-2, Sub-lingual = 0.97 ml min-1 cm-2)
Avoids hepatic first-pass metabolism

What are other factors that affect oral delivery? (4)

residence time
taste
irritation
compliance

What is the bioavailability of subingual nitroglycerin?

38%
- rapidly absorbed sublingually

What happens to sublingual nitroglycerin?

trinitroglycerine to dinitroglycerin to monoglycerine to glycerine

What are alternative administration routes of the buccal testosterone delivery? (4)

oral
IM
SC implant
dermal (patches or gel)

Controlled drug delivery system

What is buccal testosterone delivery like? (2)

well tolerated for long-terms use
common adverse events are local irritation and dysgeusia

What are traditional treatment of BCP of opioid delivery? (2)

- background analgesia - typical breakthrough pain episode before treatment with normal release opioid

What are treatment with quick onset and short duration of BCP of opioid delivery? (2)

- background analgesia - treat with ideal rescue medicine during typical breakthrough pain episode

What is the opiod delivery of buprenorphine? (3)

- outpatient treatment of opiod addiction - as effective as methadone, generally safe and well-tolerated - once daily sublingual tablet

What is the oral transmucosal insulin delivery composed of? (6)

- insulin - surfactant - solubiliser - micelle-creating agent - emulsifying agent - [all exceipient found on the FDA GRAS list]

What are features of transmucosal insulin delivery? (8)

- Needle-free - Rapid onset of action - No lung deposition (absorption in the buccal mucosa) - Established safety profile (FDA approved excipients) - Precise dose control (meets USP guideline) - Expected Improvement in Compliance - Easy self-administration - Convenient to carry and handle

What are advantages of sublingual/buccal delivery? (8)

- access and ease - large SA - rich blood supply - low metabolism - avoids hepatic first pass - low variability - prolonged contact - alternative to oral delivery

What are disadvantages of sublingual/buccal delivery? (5)

- high MW drugs must be potent - adverse reactoins - saliva & mucus - acceptance - development cost

What is the rectal drug administration an excellent route of drug delivery for? (6)

- Unconscious patients * Children * Patients that are nauseous/vomiting * Patients with upper GI tract disease * Drugs with an objectionable taste * Drugs extensively degraded via oral delivery

What are rectal dosage forms? (5)

- suppositories - capsules - tablets - ointments, creams & gels - solution, emulsions & suspensions

What is the rectal anatomy? (6)

- Last 15-20 cm of the colon - Upper and lower regions - ~300 cm2 (no villi) - Normally empty - ~3 ml mucus - pH ~7.5 - little buffering capacity

What is transcellular and paracellular absorption dependent on? (4)

- size - lipophilicity - ionisation - simple epithelium

What is rectal delivery like? (3)

- sustained release and absorption possible - metabolism of some drugs by bacteria - no esterase/peptidase activity - possible route for protein delivery

What is the rectal blood supply like? (4)

- highly vascularised - venous drainage (inferior & middle veins, lower) (superior vein, upper) - avoids hepatic first pass - complicated by anastomoses

What is the first pass avoidance of diazepam gel?

- metabolised to desmethyldiazepam (major metabolite; active) by CYP2C19 and CYP3A4 in liver (two minor active metabolites)

What is diazepam gel who for and what for? (2)

- management of selected, refractory epileptic patients - used to control bouts of increased seizure activity

What are advantages of diazepam gel? (5)

- Very low incidence of respiratory depression - Low potential for abuse - Does not require trained healthcare professional to administer injection - Serious consequences from overdose of rectal gel are rare - However, under-administration may be an issue (failure to control seizures)

What are advantages of rectal delivery? (7)

- safe and painless - avoids degradation in GI tract - avoids hepatic first pass - good range of dosages possible - potential extended absorption - good alt in certain patient groups - potential for protein delivery

What are disadvantages of rectal delivery? (5)

- acceptability (long term) - upwards movement leads to hepatic first pass - insertion issues - slow absorption (compared to oral and iv) - leakage