Routes of administration and formulation

Question 1

what routes of administration does no have to be absorbed into circulation?

Answer 1

IV or dugs intended for local effects.

Question 2

what can route of administration influence?

Answer 2

onset of action, dose, toxicity

Question 3

Parenteral

Answer 3

Associated with administration via injections

IV, IM, S/C

Question 4

Intramuscular formulation

Answer 4

Depot - active ingredient is released at a constant rate

e.g. depo-provera

Question 5

Parenteral implants

Answer 5

Depot of drug delivery - inserted s/c or sub-dermal
Designed for constant release over a long period of time
Requires surgical implantation under the skin
e.g. jadelle

Question 6

Buccal/sublingual

Answer 6

B = inner cheek
S/L = under tongue
Rapid absoption, avoids first pass effect
E.g. GTN, prochlorperazine

Question 7

Oral formulations

Answer 7

Multiple formulations to create short/intermediate/long-acting drugs

Question 8

Membrane controlled tablets

Answer 8

E.g. diltiazem (cardizem)
capsule contains pellets with membranes of differing thickness - the rate of diffusion is controlled by the membrane thickness - allows for ER

Question 8

Membrane controlled tablets

Answer 8

E.g. diltiazem (cardizem)
capsule contains pellets with membranes of differing thickness - the rate of diffusion is controlled by the membrane thickness

Question 9

Non-eroding matrix

Answer 9

e.g. potassium chloride - span K
K+ crystals are embedded in an inert waxy base - diffusing slowly across that base as the tablets pass through the GI tract - allows for ER

Question 10

Non-eroding matrix with micropores

Answer 10

e.g. oxycodone
Crystals in inert waxy base but with channeling agents that are dissolved by the GI fluids creating pores which the drugs diffuses through - allowing for ER

Question 11

Gel-forming hydrocolloids

Answer 11

e.g. verapamil
incorporates hydrophilic gel-forming polymer with drug dispersed throughout
Contact with GI fluids causes swelling of the gel layer - release of the drug is through the drug diffusing through this gel layer and gradual erosion of the gel layer

Question 12

Osmotic systems

Answer 12

e.g. nifedipine
inert semipermiable shell with the drug and an osmotic agent inside
A small laser drilled opening is on the shell surface
As water enters the tablet by osmosis it forces the drug to be expelled at a constant rate

Question 13

Rectal

Answer 13

e.g. suppositories, enemas - paracetamol, pentasa
systemic and local effects
reduces first-pass metabolism - approx half of blood supply from rectum goes straight to systemic circulation and half via the portal vein - first pass is about 50%

Question 14

vaginal route

Answer 14

e.g. estriol - ovestin,

no first pass effect, only a few agents able to be delivered this way

Question 15

Inhaled route

Answer 15

e.g. salbutamol, beclomethasone

both local and systemic effects

Question 16

Transdermal

Answer 16

systemic effects through absorption via the skin
e.g. GTN, fentanyl, nicotine
through passive diffusion across a concentration gradient

Question 17

Nasal/ophthalmic/aural route

Answer 17

Generally local effect - at the site of administration

Maybe systemic absorption

Question 18

Topical routes

Answer 18

Ointment - active ingredient in a greasy base - creates ‘occlusive dressing’
Creams - semi-solid emulsions (oil in water and water in oil - more greasy and like ointments)
Gels - molecules of liquid within a solid framework
Pastes - up to 50% of powder
Lotions - liquids in solution or emulsions - useful for hairy areas