revision lecture answers pharmacology

• Give an example of how you would record on a record card, the use of an ocular diagnostic drug in clinic? (4 marks)

  ·         Check – correct drug, dosage, expiry date, pre-assessment checks.

  ·         Record – drug(s) used, batch number, expiry date, time instilled.

  ·         Explain – why you are instilling drug? Effects drops may have. How long effects might last? Potential side effects. Advice if something goes wrong.
• A 10-year-old girl presents in May complaining of itchy and watery eyes, ongoing for a number of weeks and had hay fever symptoms last summer. After examination you diagnose seasonal allergic conjunctivitis and offer eye drops to help manage her symptoms.

  State your drug of choice to manage this patient’s presenting symptoms, as an entry level practitioner.

  sodium comoglicate 2%, GSL (can be P med), 4 times daily, for hayfever symptoms but has a delayed affect
• A 40-year-old female, with blue irises, presents routinely for an eye examination. She has physiological miosis and you find it difficult to view the peripheral fundus. You decide to perform a dilated slit lamp examination to help view the peripheral retina.

  State your drug of choice, including the concentration and legal category, for this patient.

  1.       Drug name – tropicamide.

  2.       Concentration – 0.5% or 1%

  3.       Legal category – PoM.
• Mechanism of action for cycloplegic drugs.


  Block •       the actions of the parasympathetic nervous system - antimuscarinics / anticholinergics / cholinergic antagonists / muscarinic antagonists.

  During cycloplegia, when the muscarinic receptors at the ciliary muscle and iris sphincter are directly blocked they are no longer receptive to acetylcholine and accommodation is not possible.

  Contraction of the ciliary muscle is blocked and the iris sphincter muscle is relaxed , the iris dilator innervation (sympathetic ) is then unopposed

  Resulting in cycloplegia and mydriasis
• Mechanism of action for sympathomimetic drugs.

  Phenylephrine is a sympathomimetic, specifically alpha 1 adrenergic agonist.

  It causes contraction of dilator muscle of pupil, resulting in pupil dilation (mydriasis) and conjunctival blood vessel vasoconstriction.
•   If the patient has episcleritis, the conjunctival hyperaemia will blanch (superficial episcleral vessels only) with the use of phenylephrine due to its vasoconstriction properties.

  ·         The action on the pupil dilator can be used to maximise pupil dilation in patients where this is of upmost importance such as suspicion of a peripheral retinal tear.

  ·         Using this drop in conjunction with tropicamide or cyclo will therefore have action on both the pupil dilator and pupil sphincter muscles.