Administering drugs topically Flashcards
(42 cards)
Why are some drugs NOT administered orally?
Due to biological and chemical properties = the drugs may be destroyed and thus, not carry out the purpose its was created to do.
Due to risk of systemic side effects = whole spread side effects.
Which two effects are demonstrated when drugs are administered?
- Systemic Effect
- Local Effect
Which three routes are used via the systemic administration?
Enteral = Oral Parenteral = Injections ( IV / IM / SC / IA / ID ) Topical = Sub - lingual / Transdermal Patch / Inhalation / Rectal
Which route is used via the local administration?
Topical = Creams / Intranasal Sprays / Occular Drops
Explain topical administration in terms of producing a local effect.
The drug is applied to a localised area of body surface in order to minimise systemic side effects and systemic absorption.
Explain topical administration in terms of producing a systemic effect.
Thee drug is applied to the body surface in order tot provide an alternative / convenient route into the blood.
What happens when a drug is administered via oral tablet?
First pass metabolism in the liver occurs = therefore, the drug enters the liver first.
What happens when a drug is administered via IV?
Enters the blood directly. (DIRECT ACCESS)
How can you bypass first pass liver metabolism?
Increase the dosage of the drug
Administer the drug via another route.
What happens when a drug is administered via buccal?
Reaches the body first and then the liver.
What happens when a drug is administered via topical?
Reaches the body site DIRECTLY.
Absorption via the skin and thus, systemic action occurs.
Results in stable blood levels.
What conditions is the topical local administration used for?
Skin = Eczema Eye = Conjunctivitis Nose = Hay - Fever Lung = Asthma Vagina = Thrush Rectum = Constipation
What conditions is the topical systemic administration used for?
Skin = Contraception
Mouth (mucosal membranes) = Chest Pain
What formulation is used to deliver drugs administered topically for the skin?
Cream Ointments Powder Lotions Gels Transdermal Patch
What formulation is used to deliver drugs administered topically for the nose and lungs?
Solutions and Powders
What formulation is used to deliver drugs administered topically for the eye or ear?
Solutions
Ointments
Creams
What formulation is used to deliver drugs administered topically for the rectum / colon?
Foams
Enemas
Suppositories
What formulation is used to deliver drugs administered topically for the vagina?
Creams
Pessaries
How are drugs are absorbed into the skin?
Drugs diffuse from the stratum corneum in to the epidermis into the dermis.
From the dermis it enters the capillary microcirculation.
Then from there, it enters the systemic circulation.
What is the stratum corneum?
Outer layer of the epidermis.
The permeability barrier of the skin.
What does lipophilic drug mean?
Utilises the intracellular route (crosses the cell wall)
= Goes THROUGH the cells.
What does hydrophilic drug mean?
Utilises the intracellular route (diffusing in fluid filled spaces between the cells)
= Goes AROUND the cells.
What layer does the drug have to pass in order to reach the site of action?
Epidermis Layer.
What is the partition coefficient?
Ratio of concentrations of compounds in mixture of 2 substances = This mixture is IMMISCIBLE.
