Drug Formulations and Routes of Administration Flashcards
What is formulation?
Also known as “dosage” form, it is the form in which a pharmaceutical product is presented for therapeutic use (eg tablet, cream, aerosol)
What is route of administration?
One of many ways by which a drug is delivered to the body
What factors determine the most appropriate route of administration?
- Site of action
- Symptoms (oral delivery impossible if patient vomits)
- Technical / formulation capability (tablet cannot be applied in the same kind of way as a syringe, however usually same route of administration can be used for both local and systemic delivery depending on purpose of treatment)
What is oral (enteral) administration?
Administration to or by way of the mouth
Most common route, involves swallowing the formulation into GI tract, followed by intestinal absorption of the drug
Usually for systemic drug delivery
What are the advantages of oral administration?
Non-invasive
Patient can self-administer
Simple and convenient
Economical formulation production because sterilisation is not needed
What are the disadvantages of oral administration?
Slower onset of action
High acidity in stomach and digestive enzymes in the GI tract can destroy the drug eg insulin
First-pass metabolism by the liver
Not suitable for bitter or strong smelling drugs
Not suitable for unconscious or vomiting patients
What are types of oral formulations?
Solids = tablets and capsules Liquids = syrup, elixer, and oral drops
What are tablets?
Powder containing the drug and excipients (diluents, binders, lubricants etc) compressed into a hard mass
Can be for immediate or controlled/sustained drug release
Most tablets are swallowed whole but there are also chewable, orally disintergrating or effervescent tablets
What are capsules?
Power or liquid contained in a shell made from a polymer, usually gelatin
Available as hard and soft capsules
What are the differences between the oral formulations: syrup, elixer, and oral drops?
Syrup = solution containing a high concentration of sucrose or other sugars
Elixir = Flavoured / sweetened hydroalcoholic solution
Oral drops = solution, emulsion, or suspension administered in small volumes by a suitable device (eg dropper)
In terms of liquid formulations, what is a solution?
Drugs and excipients dissolved in a solvent (water only) or a mixture of miscible solvents (eg water and ethanol)
One-phase system, homogenous
In terms of liquid formulations, what is an emulsion?
One liquid dispersed as small droplets throughout another liquid
Oil-in-water or water-in-oil
Two-phase system
In terms of liquid formulations, what is suspension?
Solid particles dispersed throughout another liquid
Solid-in-liquid
Two-phase system
What is sublingual administration?
Administration beneath the tongue
Available as sublingual tablets or sublingual sprays
What is buccal administration?
Administration directed toward the cheek, generally from within the mouth
Buccal tablet placed on the inside of the cheek between the gum and lip
What are the advantages of sublingual and buccal administration?
Good for systemic drug delivery - fast onset of action due to a high blood supply in oral mucosa, leading to rapid drug absorption, no first-pass metabolism
Sublingual / buccal tablets can be removed anytime when adverse effects occur
What are the disadvantages of sublingual and buccal administration?
Not suitable for bitter or strong smelling drugs
High molecular weight drugs (eg proteins and peptides) cannot be absorbed
What are injections / parenteral administration?
Administrations by needle
Liquid, sterile formulations
Numerous possible sites of injection depending on the treatment of purpose
What are the possible sites / depths of injections?
Intravenous - within veins (chemotherapy, antibiotics)
Intramuscular - within muscles (vaccines)
Subcutaneous - beneath the skin (insulin)
Intradermal - within the skin (allergy testing)
The angle / depth of the needle determines the route of injection. What are the correlating depths and angles?
Intramuscular = 90 deg, deepest Subcutaneous = 45 deg Intravenous = 25 deg Intradermal = 10 - 15 deg, shallowest
What are the advantages of intravenous administration?
Directly delivers the drug into systemic circulation
By definition, 100% bioavailable
Fast onset of action so valuable in an emergency, suitable for unconscious or vomiting patients
Small (several ml eg bolus) and large volumes (up to litres eg infusion) can be injected
Drug does can be controlled accurately
What are the disadvantages of intravenous administration?
Invasive, painful
Needs qualified healthcare profession to administer
Needs aseptic technique
Risky because once the drug is injected it cannot be recalled
Introduction of air (bubble) or particulate matter may cause embolism and potentially fatal
What are the advantages of intramuscular administration?
Drug absorption is more predictable, less variable, and more rapid compared to oral route due to blood vessels serving the muscles
Sustained release formulations can be injected
No first-pass metabolism
What are the disadvantages of intramuscular administration?
Invasive, painful
Needs qualified healthcare professional to administer and needs aseptic technique
Only small volumes (typically 2 - 5ml) can be injected
