Pharmacology : Drug Administration
- Created by: Sophie
- Created on: 16-01-13 12:42
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- Drug Administration
- Delivery
- Drugs are available in diff. forms
- Determined by:
- Chemical/ biological stability
- Route of admin
- Convenience
- Formulation
- Determined by:
- Chemical/ biological stability
- Route of admin
- Convenience
- Formulation
- Formulation
- Convenience
- Route of admin
- Chemical/ biological stability
- Determined by:
- Formulation
- Convenience
- Route of admin
- Chemical/ biological stability
- Determined by:
- Main routes of admin
- Inhalation
- Sublingual
- Oral
- Application to epithelial surfaces
- Rectal
- Injection
- Main routes of admin
- Inhalation
- Sublingual
- Oral
- Application to epithelial surfaces
- Rectal
- Injection
- Injection
- Rectal
- Application to epithelial surfaces
- Oral
- Sublingual
- Inhalation
- Main routes of admin
- Injection
- Rectal
- Application to epithelial surfaces
- Oral
- Sublingual
- Inhalation
- Drugs are available in diff. forms
- Routes involving GI tract
- Sublingual
- Drug must not have unpleasant taste
- Under the tongue
- Only for small MW drugs
- Rapid absorption from mouth to systemic circulation
- This way avoids:
- pH of stomach
- passage through liver in portal circulation
- This way avoids:
- Rapid absorption from mouth to systemic circulation
- Only for small MW drugs
- Under the tongue
- This way avoids:
- pH of stomach
- passage through liver in portal circulation
- Drug must not have unpleasant taste
- Oral (aka per oralis)
- Most common route
- Bioavailability
- Defined as proportion of admin. dose that is delivered to systemic circulation
- Ionisation of drug affects absorption
- Most drugs are weak acids or weak bases
- pH in gut affects ionisation
- Absorbed drug lost to metabolism by enzymes in gut and liver
- Bioavailability
- Defined as proportion of admin. dose that is delivered to systemic circulation
- Ionisation of drug affects absorption
- Most drugs are weak acids or weak bases
- pH in gut affects ionisation
- Absorbed drug lost to metabolism by enzymes in gut and liver
- Ionisation of drug affects absorption
- Defined as proportion of admin. dose that is delivered to systemic circulation
- Bioavailability
- Ionisation of drug affects absorption
- Defined as proportion of admin. dose that is delivered to systemic circulation
- Rectal
- Drug delivered as; suppository (wax base), enema (liquid)
- For local inflammation
- For systemic effects
- Sublingual
- Routes involving epithelial surfaces: topical for local
- Most drugs are weakly absorbed across skin
- Nasal mucosa- nasal sprays
- Cornea- eye drops
- Nasal mucosa- nasal sprays
- Topical for systemic
- Some drugs cross skin due to high-lipid solubility
- Delivered as; liquids, ointments, transdermal patches
- Some drugs cross skin due to high-lipid solubility
- Most drugs are weakly absorbed across skin
- Injection
- Intravenous
- Fastest route to systemic
- Drug delivered as sterile liquids
- Used for:
- Seriously ill, unstable drugs, drugs poorly absorbed
- Used for:
- Drug delivered as sterile liquids
- Fastest route to systemic
- Subcutaneous
- Injection under skin
- Faster than oral, slower than IV
- Rate depends on:
- Drug diffusion and removal by local bl. flow
- Rate depends on:
- Faster than oral, slower than IV
- Injection under skin
- Intramuscular
- Into muscle
- Similar to SC but slower
- Into muscle
- Intradermal
- Into skin
- Breaks dermis layers
- Local effect; Not used for systemic effect
- Very slow release
- Local effect; Not used for systemic effect
- Breaks dermis layers
- Intracerebro-ventricular
- Into ventricles of brain
- For drugs that can't pass through blood-brain barrier
- eg.antiobiotics
- For drugs that can't pass through blood-brain barrier
- Epidural (Intrathecal)
- Into a subarachnoid space by lumbar puncture
- For drugs that can't pass blood-brain barrier
- For local admin.
- For drugs that can't pass blood-brain barrier
- Into a subarachnoid space by lumbar puncture
- Into ventricles of brain
- Into skin
- Intravenous
- Inhalation
- Delivery to lungs in inspired air
- Systemic effects
- Gases
- Gas molecules dissolve in lung fluids
- Diffuse into bl. in pulm. circulation
- Rapid exchange between bl. and gas phase
- Diffuse into bl. in pulm. circulation
- Gas molecules dissolve in lung fluids
- Local effects
- Inhalation
- Delivery to lungs in inspired air
- Systemic effects
- Gases
- Gas molecules dissolve in lung fluids
- Diffuse into bl. in pulm. circulation
- Rapid exchange between bl. and gas phase
- Diffuse into bl. in pulm. circulation
- Gas molecules dissolve in lung fluids
- Local effects
- Delivered as liquid droplets/ fine powders
- Importance of particle size:
- >10 microns - hit throat + swallowed
- <10 - enter lungs
- <1 micron - enter lungs but cross into bl. for systemic effects
- Importance of particle size:
- Delivered as liquid droplets/ fine powders
- Gases
- Systemic effects
- Delivery to lungs in inspired air
- Delivered as liquid droplets/ fine powders
- Importance of particle size:
- >10 microns - hit throat + swallowed
- <10 - enter lungs
- <1 micron - enter lungs but cross into bl. for systemic effects
- Importance of particle size:
- Inhalation
- Gases
- Systemic effects
- Delivery to lungs in inspired air
- Dose
- Amount of drug administered
- Taken as single dose or bolus
- concentration = amount/volume
- Drug conc.determines effect
- Body volume
- Dose expressed relative to body weight (mg/kg)
- Dose should vary with body size
- Placebo effect
- Can be as high as 50% in some diseases
- Some people are helped by taking a 'medicine' in some diseases, even if a tablet of chalk
- concentration = amount/volume
- Taken as single dose or bolus
- Amount of drug administered
- Delivery
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