5- Pharmacology 2 Flashcards
What is pharmacokinetics?
The study of the movement of drugs into, around, and out of the body. “What the body does to the drug.”
What is pharmacodynamics?
The study of how drugs work when they reach their site of action. “What the drug does to the body.”
On what mechanisms may drugs act?
Components of the cell.
Critical chemical pathways of the cell.
Transport mechanisms for chemicals entering and exiting cells.
Chemical messaging systems between cells.
DNA/RNA replication.
What are the two categories of transport mechanisms?
Passive Transport: Diffusion, osmosis, and facilitated diffusion.
Active Transport: Uses ATP.
Give examples of chemical messengers involved in drug actions.
N,A,G,D,S
Noradrenaline (NA)
Acetylcholine (Ach)
Gamma-aminobutyric acid (GABA)
Dopamine (DA)
Serotonin (5HT, 5-hydroxytryptamine)
What is the “lock and key” mechanism of drug-receptor interaction?
Drug molecules bind to receptor sites like a key fitting into a lock, leading to:
Agonist: Enhances action.
Antagonist: Diminishes action.
Partial agonist: Dampens down action.
What happens when a B2 agonist binds to a B2 adrenoceptor?
Enhances receptor action.
Dilates the airways (e.g., salbutamol for asthma).
What happens when a B1 blocker binds to a B1 adrenoceptor?
r,v,l
- Reduces receptor action.
- Vasodilation
- Lowers blood pressure (e.g., atenolol, propranolol).
What does an anticholinergic agent like atropine do at cholinergic receptors?
Anticolinergics block the action of AcH
Thus, Dilation of the pupil (mydriasis).
How do SSRIs affect serotonin levels?
They increase serotonin concentration outside the receptor, enhancing mood.
What does buprenorphine do at opiate receptors?
Provides moderate pain relief.
Reduces potential for opiate addiction.
Useful in substance misuse treatment.
Through which areas are eye drops absorbed?
Primarily through the cornea.
Also through the conjunctival mucosa, which can lead to systemic effects.
Why are frequent applications of eye drops needed?
Eye drops have a short drug-eye contact time.
What are unit dose (UD) eye drops also known as
Preservative-free eye drops.
What are the advantages of eye ointments over eye drops?
Prolonged contact time, requiring less frequent application.
Lubricates the eye, reducing the need for concurrent lubricants.
What are the disadvantages of eye ointments?
Blurred vision
What formulations are used to treat posterior segment of the eye
Intravitreal injections.
Periocular injections.
Systemic administration (oral medicines
How many drops are in 1 mL of eye drops?
Approximately 20 drops per 1 mL (fewer for more viscous drops).
Why should there be a 5-minute gap between different eye drops?
To prevent the second drop from washing out the first before full absorption.
What medications can orthoptists administer without prescription
6- LLAF MC
Local anaesthetics.
Fluorescein.
Antimicrobials.
Lubricants.
Mydriatics.
Cycloplegics.
Which drugs act on the cornea?
LFAL
Local anaesthetics.
Fluorescein.
Antibiotics.
Lubricants.
What drugs act on the iris
Mydriatics (e.g., cyclopentolate) dilate the pupil
What drugs act on the ciliary muscle
Cycloplegics (e.g., atropine, tropicamide) paralyze the muscle.
What is the action of fuscidic acid
Effective against gram-positive organisms, especially Staphylococcus aureus.
Prolonged contact in the conjunctival sac ensures effectiveness with twice-daily application.
Why must soft contact lenses not be worn during treatment with fusidic acid eye drops?
The preservative benzalkonium chloride can irritate eyes and discolor contact lenses.
What are the pharmacodynamics of fusidic acid
**Fusidic acid acts as a bacteriostatic agent, inhibiting bacterial protein synthesis by blocking peptide chain elongation.
It is effective against a wide range of Gram-positive bacteria, especially Staphylococcus aureus.
Does fuscidic acid kill bacteria directly (bactericidal)
No, but it stops their replication and protein synthesis, effectively halting bacterial growth.
Fuscidic acid- how long after contact do bacterial cells stop dividing
within 2 minutes, while DNA and RNA synthesis continues for 45 minutes to 1-2 hours, respectively
What are the potential undesirable effects of fuscidic acid
Local effects:
Eye irritation (stinging or burning upon instillation).
Conjunctival hyperemia (redness).
Allergic reactions such as itching or swelling.
Systemic effects: Rare due to minimal systemic absorption. However, trace amounts can sometimes cause mild systemic reactions such as nausea or gastrointestinal discomfort.
What are the pharmacodynamics of atropine
Anticholinergic effects:
Atropine is a competitive antagonist of acetylcholine at muscarinic receptors in the parasympathetic nervous system.
More on atropine pharmacodynamics
Inhibition of the iris sphincter muscle leads to mydriasis (dilation of the pupil).
Relaxation of the ciliary muscle leads to cycloplegia (paralysis of accommodation).
What is the onset of atropine
Pupillary dilation typically occurs within 30 minutes of local application and may last for 7 days or longer.
Onset and duration of cycloplegia develop with Atropine
onset - 15–30 min
duration- 4–6 h.
How long does atropine last
3-7 days
What is the combination of lidocaine with fluorescein used for
Common Form: Lidocaine 4% + Fluorescein 0.25% solution (eye drops).
📌 Purpose: A combination used in ophthalmology for diagnostic procedures.
📌 Key Uses:
**Topical Anesthesia ** tonometry, foreign body removal, and eye exams.
**Corneal Staining – Fluorescein highlights abrasions, ulcers, or damage under blue light.
Glaucoma Testing – IOP measurement.
Contact Lens Fitting – Helps assess lens alignment and corneal staining.
📌 How It Works:
**Lidocaine **→ Numbs the eye.
**Fluorescein **→ Stains damaged areas, making them visible under blue light.
What is the purpose of Lidocaine with fluoroscein
Diagnostic purposes, such as in tonometry or contact lens fitting, without causing significant systemic effects.
Pharmacokinetics of Lidocaine with Fluoroscein
ADME
Absorption: Lidocaine is absorbed locally in the eye with minimal systemic absorption.
Distribution: Not applicable as most of the action is local.
Metabolism: Lidocaine is metabolized in the liver, though the risk of systemic absorption is negligible in ocular use.
Elimination: Lidocaine is eliminated via the kidneys, with trace amounts excreted as unchanged drug.
Who is most effected by dry eye?
women or men and during which life stage
7% of people 50s
15% of people in their 70’s
Women are affected more frequently than men, especially during menopause due to hormonal changes.
When should preservative-free ocular lubricants be used
-In patients with allergies or epithelial toxicity to preservatives.
-When the patient requires more than 4-6 applications of eye drops daily.
-After eye surgery, until healing is confirmed.
-If a patient needs to use dry eye drops more frequently than 4 times daily, a more viscous lubricant should be used.
What is an advantage of preservative free formulations
They reduce the risk of irritation or toxicity from preservatives and can be used for up to 2-6 months after opening without contamination.
What is the pharmacokinetics of Sodium Cromoglycate?
ADME
Absorption: Poor systemic absorption; only trace amounts (less than 0.01%) penetrate into the aqueous humour.
Distribution: Not applicable as it has minimal systemic effects.
Metabolism: Not significantly metabolized.
Elimination: Sodium cromoglycate is cleared from the aqueous humour within 24 hours after stopping treatment.
What are the pharmacodynamics of sodium cromoglycate
Sodium cromoglycate is a mast cell stabilizer, inhibiting the degranulation of sensitized mast cells after antigen exposure.
What does sodium cromoglycate prevent
It prevents the release of histamine and other mediators from the mast cells
Has sodium cromoglyacte got
vasoconstrictor or antihistamine activity
No
What is sodium cromoglycate used to treat
seasonal and perennial allergic conjunctivitis and provides relief from symptoms like itching and redness.
What are the adverse effects of Sodium Cromoglycate?
Local irritation: Transient stinging or burning on instillation of the drops.
Rare side effects: Other symptoms of local irritation can occur, but systemic side effects are unlikely due to minimal absorption.
What does an agonist do
Agonist: Enhances action.
What does an antagonist do
Diminishes action
What does a partial agonist do
Partial agonist: Dampens down action.
Which of the following neurotransmitters is a major inhibitory neurotransmitter in the central nervous system?
Gamma-aminobutyric acid (GABA)
Which of the following best describes the action of a partial agonist?
Partially activates the receptor while preventing full activation
What is the mechanism of action of proton pump inhibitors (PPIs)?
They irreversibly inhibit H+/K+ ATPase
Which drugs is a beta-1 selective antagonist?
propanolol
Whats the primary site of absoprtion for most eye drops?
cornea
Which of the following best describes the function of selective serotonin reuptake inhibitors (SSRIs)?
Increase serotonin availability by blocking its reuptake
What is the main mechanism by which fusidic acid acts as an antibacterial agent?
Blocks bacterial protein synthesis by interfering with elongation factor G
Which of the following eye formulations allows for the longest drug contact time?
Eye ointments
Where is atropine eliminated
the liver
Why are eye drips applied freqiently
they have a short drug- eye contact time
Which drugs are used to treat opioid addiction due to its partial agonist properties?
naloxone or buprenorphine
How many drops are in a 10mL bottle
200
What is the main reason for allowing a 5-minute gap between different eye drops?
prevents the first drop from washing out
Which of the following is a clinical application of fluorescein?
staining corneal abrasions
Why are beta blockers used in opthalomolgy
lower IOP
A partial agonist at opioid receptors would have which of the following properties?
Competes with full agonists for receptor binding
What is the mechanism of action of acetazolamide in glaucoma treatment?
Inhibits carbonic anhydrase, reducing aqueous humor production
