pharmacology

• What does direct sympathetic innervation on alpha receptors in the eye cause?

  Mydriasis
• What is false about cocaine's effects?

  • Cocaine does cause pupil mydriasis when used topically
  • It blocks the enzyme responsible for the breakdown of norepinephrine
  • It blocks the synaptic reuptake of norepinephrine
  • Cocaine is an indirect acting sympathomimetic
• What are the neurotransmitters and receptors of the ANS branches?

  • Sympathetic:
  • Neurotransmitter: Noradrenaline
  • Receptors: Adrenergic (Alpha & Beta)
  • Agonist: Activate / Mimetic / Stimulant
  • Antagonist: Block / Occupy / Lytic

  
  

  • Parasympathetic:
  • Neurotransmitter: Acetylcholine (ACh)
  • Receptors: Muscarinic (& Nicotinic)
• What are the effects of sympathomimetic agonists on the eye?

  • Stimulate or enhance receptors of the sympathetic branch
  • Direct: Stimulate adrenergic receptors directly (alpha, beta)
  • Indirect: Increase synaptic activity by releasing or reuptaking neurotransmitters
  • Effects:
  • Mydriasis (alpha 1 receptor)
  • Light reflex remains intact
  • Reduction of intraocular pressure (IOP)
  • Reduced aqueous humor (AH) secretion (alpha agonist)
  • Vasoconstriction of conjunctival blood vessels
  • Increased viscous lacrimal gland secretion
  • Increased palpebral aperture (due to Muller’s muscle)
• How do sympathomimetics aid in diagnosing Horner’s Syndrome?

  • Interruption of any part of the sympathetic pathway
  • Ocular manifestations: miosis, ptosis, reduced sweat secretions
  • Cocaine test: blocks synaptic reuptake of norepinephrine
  • Healthy eye pupil dilates
  • Abnormal pupil remains miosed if damage is post-ganglionic
  • Abnormal pupil dilates if damage is below the superior cervical ganglion
• Which drug is associated with intra-operative floppy iris syndrome during cataract surgery?

  Tamsulosin
• What is an indication for the use of Prazosin?

  Benign prostatic hyperplasia
• Which type of drug can open airways wider to alleviate asthma or COPD?

  Sympathomimetic
• What are the effects of alpha adrenergic blockers on the eye?

  • Relaxes smooth muscle
  • Indirectly on iris dilator, causing miosis
  • Poor response to pre-surgical dilating drops
  • Iris prolapse or billowing during surgery
  • Vasodilation
  • Conjunctival hyperaemia
• What are some symptoms of anaphylaxis?

  • Allergic conjunctivitis
  • Rhinitis
  • Pupil dilation
  • Hypertension / Migraine
  • Heart failure
  • Asthma/COPD
  • Salbutamol
• Which drug class has a caution regarding susceptibility to angle closure?

  Alpha-adrenoceptor blockers
• How can drugs that dilate the pupil increase the risk of angle closure?

  • Drugs with anti-cholinergic effects or sympathomimetic effects can dilate the pupil
  • Anticholinergic effects:
  • Block muscarinic receptors and release of ACh
  • Result in reduced accommodative function and pupil mydriasis
  • Pupil dilation makes the angle narrower as the iris bunches up
  • Risk is higher in patients with:
  • Narrow angles due to hypermetropia, cataract, or mature lens
• What are the important considerations before using phenylephrine eye drops?

  • Gather information about the patient
  • Ask relevant questions:
  • Blood pressure, heart or circulation problems
  • Thyroid issues
  • Diabetes duration
  • Asthma
  • Medications (especially blood pressure and antidepressant types)
  • Glaucoma history or treatment
  • Past experiences with pupil-dilating eye drops
  • Dry or irritated eyes
• What are the effects of a vasoconstrictor sympathomimetic?

  Increases heart rate, constricts blood vessels
• Which medication might Tom take for hayfever?

  Chlorphenamine
• How are chlorpheniramine's effects enhanced by other drugs?

  • Other antimuscarinic drugs enhance both antimuscarinic and sedative effects
  • Monoamine oxidase inhibitors (MAOIs) and tricyclic antidepressants enhance the effects
• What caution related to chlorphenamine must be considered when Tom requires pupil dilation for cycloplegic refraction?

  Susceptibility to angle closure
• In which drug class is pilocarpine, and what effect does it have on the eye?

  Antimuscarinic, causes miosis
• How does pilocarpine treatment for presbyopia affect the eye?

  • Stimulates muscarinic receptors in the iris and ciliary muscle
  • Causes contraction of the ciliary muscle and miosis
  • Lens thickness increases
  • Phase 3 GEMINI 1 & GEMINI 2 Clinical Studies:
  • No significant drop in distance visual acuity versus placebo (n=750)
• For which condition is citalopram commonly used?

  Depression
• What is the drug class and mechanism of action of citalopram?

  • Drug class: Selective Serotonin Re-uptake Inhibitors (SSRIs)
  • Mechanism: Inhibits CNS central uptake of serotonin
  • Milder indirect anticholinergic effects than other SSRIs or tricyclic antidepressants
• What are the effects of the parasympathetic nervous system on the eye?

  • Accommodation: Ciliary muscle contraction
  • Miosis: Sphincter muscle contraction
  • Enhances drainage of aqueous humor: Trabecular meshwork and canal of Schlemm
  • Increases lacrimal gland secretions
• What are the effects of the sympathetic nervous system on the eye?

  • Mydriasis: Dilator muscle contraction $(\alpha_1$ receptor)
  • Contracts Muller’s muscle: Holds eyelid open $(\alpha_1$ receptor)
  • Relaxes ciliary muscle for distant vision: $(\beta_2$ receptors)
  • Enhances aqueous humor formation: $(\beta_2$ receptors)
  • Inhibits aqueous humor formation: $(\alpha_2$ receptors)
  • Increases viscous lacrimal gland secretion (passive)
• What are the main groups of antibiotics based on their mode of action?

  They include drugs that interfere with DNA synthesis, protein metabolism, the plasma membrane, and the construction of the cell wall.
• What is the difference between bacteriostatic and bacteriocidal antibiotic actions?

  Bacteriostatic prevents growth, while bacteriocidal kills bacteria.
• How do drugs that inhibit folate metabolism typically act on bacteria?

  They inhibit the synthesis of folate and the action of folate, resulting in bacteriostatic action.
• What are the key components involved in folate metabolism in bacteria?

  • PABA (p-aminobenzoic acid)
  • Folate (Folic acid)
  • Tetrahydrofolate
  • DNA
  • Dihydrofolate reductase
  • Dihydropteroate synthase
  • Sulphonamides (sulphanilamide, sulphamethoxazole)
  • Trimethoprim
  • Co-trimoxazole (trimethoprim and sulphamethoxazole)
• What are the typical uses of drugs that inhibit folate metabolism?

  • Treatment of respiratory infections
  • Treatment of urinary tract infections
• How do drugs that interfere with DNA gyrase activity affect bacterial DNA?

  They interfere with the winding and unwinding of DNA during replication or transcription.
• What are the main differences between broad-spectrum and narrow-spectrum drugs that interfere with DNA gyrase activity?

  • Broad spectrum: ciprofloxacin, perfloxacin
  • Narrow spectrum: cinoxacin, naladixic acid (used for UTIs)
• Which drug inhibits bacterial RNA polymerase activity?

  Rifampicin
• What are the key components of the bacterial ribosome?

  • 50S subunit
  • 30S subunit
  • mRNA
  • tRNA
  • A site
  • P site
• What are the key steps in protein synthesis that antibiotics can target?

  • Transpeptidation
  • Translocation
• What are the main groups of drugs that interfere with protein synthesis?

  • Chloramphenicol
  • Aminoglycosides (gentamicin, streptomycin, neomycin)
  • Macrolides (erythromycin, clarithromycin, azithromycin)
  • Fusidic acid
• What is the structural characteristic of beta-lactam antibiotics?

  They contain a β-lactam ring that inhibits penicillin binding proteins (PBPs) involved in peptidoglycan synthesis.
• What are the main types of beta-lactam antibiotics?

  • Penicillins
  • Cephalosporins
• What are the key components involved in peptidoglycan synthesis?

  • NAMA (N-acetylmurinic acid)
  • NAG (N-acetylglucosamine)
  • Lipid carrier with phosphate groups (P)
  • Transpeptidation via transpeptidase (PBP)
  • Removal of terminal alanine from side chain
  • Cell wall
  • Plasma membrane
  • Bacteria cytosol
• Why can beta-lactam antibiotics be bacteriostatic in some organisms and bacteriocidal in others?

  Beta-lactams block inhibitors of autolytic enzymes in bacteriocidal organisms, causing lysis, but these enzymes are ineffective in bacteriostatic organisms.
• What enzyme is responsible for conferring beta-lactam resistance in staphylococci?

  β-lactamase
• How does β-lactamase provide resistance to beta-lactam antibiotics?

  It cleaves the β-lactam ring, making the antibiotic inactive.