Routes of administration Flashcards
List all routes of administration
-Sublingual + Buccal
-Ocular, Nasal,ear
-Intrathecal + epidural + Intrathymic +Intracardiac
-Inhalation
-Intravenous + inta-arterial + intramuscular
-Topical + subcutaneous
-Rectal + vaginal
- Oral
Absorption
movement of drug from site of administration to the bloodstream
What proteins are within the phospholipid bilayer?
Integral proteins imbedded in membrane
Peripheral proteins
What molecules can pass through cell membrane?
Hydrophobic, small, uncharged molecules
Protein carrier needed for charged molecules and ions
transport across biological membranes
Transcellular diffusion and passive and facilitated, endocytosis, efflux, paracellular
Use of villi and microvilli
Increase SA = more absorption within small intestine
What is gastric emptying?
- stomach pressure constant at start
- Stomach has plasticity
- 3ml pushed into Chyme and small intestine
- Is pushed in small amounts or back into stomach
-Stops chances of indigestion
What impacts gastric emptying process?
pH of stomach - More time to neutralise food if very acidic
Time of eating
Meal volume
Meal composition - Rich in carbs will move more quickly, fatty is slower
How is gastric emptying regulated?
Neural reflexes
Hormonal mechanisms
What is Gastric emptying rate?
Speed at which substance leaves the stomach after ingestion
Why is a long GER bad?
Delays absorption rate of drug in small intestine, less bioavailability
Why take food and aspirin at the same time?
Aspirin can irritate the stomach
Why take amoxicillin before food?
Food can affect absorption, will interfere with absorption of penicillin, don’t want drug to be degraded
Rate- limiting step
slowest step in series, controls overall rate and extent of appearance of the intact drug in the systemic circulation
Different types of rate-limiting steps
- Disintegrating rate
-Gastric emptying
-Dissolution - high logP hardly dissolves
-Permeability- low logP is hardly absorbed
-Metabolism in the liver (first pass effect)
How do ions pass through the small intestine?
Paracellular route in small amounts
Advantages of tablets?
Non- expiring
easy to carry
easy to swallow
elegance
very accurate dosage
High chemical and physical stability
Can’t tamper with a tablet
Low cost packaging
process of taking a tablet
Disintegration (RLS)
Deaggregation
Dissolution
Drug in solution
Gastric emptying
Difference between tablet and capsule?
Capsule has a layer of gelatin (come in hard and soft capsules)
Adv of capsule over tablets?
Capsule can be tasteless and odourless
Easier to swallow -smooth and slippery
Can be opened up and sprinkled on food
Can be printed on
Faster acting
Other dosage forms within the capsules
Dissolution of capsule process
Excipients in capsule attract water molecules to dissolve them
Quickest oral dosage form
solution - skips all rate- limiting steps can go straight into GI fluids for absorption
How does non-keratinised cells help with absorption?
More permeable for rapid onset reaction
no extra layer to prevent drug absorption like the skin
Examples of OTC oral tablets, buccal and sublingual tablets, capsules, suspensions and oral solutions?
what type of route do drugs which are inhaled take?
Pulmonary delivery–> local or systemic
when can a pharmacist supply POMs without a prescription?
In an emergency
How to use a salbutamol inhaler
- remove cap
- check does counter
-hold upright and shake well - Breathe out gently
-put in mouthpiece between teeth and close lip to form seal
-start to breathe in slowly and press on canister firmly
-continue to breathe in slowly and deeply
-hold breath about 5-10 secs
-while breathing remove from mouth
-breathe out gently
-replace cap
local or topical drug administration
Asthma
COPD
Cystic fibrosis
pulmonary hypertension
lung infections
Systemic application via lungs
CNS stimulation
Anaesthetics
diabetes
pain and migraine
appetite suppression
How we deliver drugs to or via lungs
solid in gas e.g. smoke
liquid in gas e.g. mist
gases
Branching of lungs
trachea to bronchi to respiratory bronchioles to alveolar ducts to atrium to alveoli
How lung diseases impact drug administration via inhalation
lumen being narrower impacts the drugs pathway to being absorbed, restricts airflow. Caused by obstructive and restrictive lung diseases.
what is inertial impaction
where the drug acts in the airways depending on particle size, momentum and angle of bifurcation
what is the main reason for depositing in the lower airways
sedimentation due to gravity - impacted by breath-holding
what is the dominant mechanism for particles < 0.5 micrometres
diffusion
what influences lung deposition?
particle size
particle size distribution
particle density
particle shape
particle hygroscopicity - absorption of moisture (don’t store in bathroom)
what does cilia on epithelial cells do in terms of drug absorption?
reduces drug deposition = less drug absorption
clears drug caught in mucus
what reduces local drug conc in airways?
cilia, macrophage clearance, translocation past cell to other areas of body
formulation selection for administration via lungs
check factors influencing lung deposition
inhaler types
quality control
adv and disadv of local drug delivery to lungs?
adv:
-carry around
-directly to the organ
-low dose required
-rapid onset
-fewer systemic side effects
-non-invasive delivery
disadv:
-low efficiency of delivery
-difficulty in breath coordination
-can supress immune response (corticosteroid)
-throat irritation
Adv and disadv of systemic delivery of drugs via lungs
Adv:
-Rapid onset of action
-circumvents first pass effect
-non-invasive delivery route
-good for biopharmaceuticals
Disadv:
-low efficiency
-difficulty using some devices
-breathing difficulties
- may need very low or very exact doses
-expensive compared to oral therapies
