Pharmacology

    Cards (252)

    • Unit 23 is on the subject of PHARMACOLOGY
    • Core Competencies covered in this Unit
      • Professional Conduct - The ability to manage patients in a safe, appropriate and confidential environment
      • Methods of Ocular Examination - An understanding of instrumentation used in the examination of the eye and related structures
      • Low Vision - The management of low vision patients
      • Refractive Management - An understanding of methods of assessing vision, refraction, binocular status and visual acuity in all patients
      • Ocular Abnormalities - An understanding of the relevance of ocular disease
    • The work set for this Unit includes Abnormal Ocular Conditions 2nd Ed. by Pipe and Rapley (pages 119-145) and a Dispensing Optics Special Educational Supplement from April 2010
    • Ocular pharmacology has always been part of the training of Dispensing Opticians as part of anatomy and physiology and ocular disease
    • In 2010 changes to the Medicines Act meant that both Dispensing Opticians and contact lens opticians can legally order and use a limited range of ocular drugs
    • Modes of action in which an ophthalmic drug can affect neural activity
      1. Preventing the transmission of signals in the neurone
      2. Reducing or preventing the release of the transmitter substance
      3. Promoting the release of the transmitter substance
      4. Mimicking the transmitter substance at receptor sites
      5. Preventing the breakdown of the transmitter substance
      6. Preventing the re-uptake of the transmitter substance
    • Agonist
      Drugs that bind to and activate receptors thereby producing a response
    • What Dispensing Opticians should be able to do regarding ocular drugs
      • Recall the common drugs used in optometric practice
      • Understand how appropriate ocular drugs can be used to aid refraction
      • Understand how appropriate ocular diagnostic drugs can be used to aid ocular examination and investigation
      • Show an appreciation of the clinical treatment of a range of systemic diseases with ocular manifestations and adverse ocular reactions to medication
    • Antagonist
      Drugs that bind to but do not activate receptors. They can also block the effects of an agonist which may be an endogenous substance
    • Use and advantages of Minims
      • Single Dose
      • Sterile until opened
      • Used for one patient only
      • Reduces the risk of cross-infection and contamination
      • Preservative-free
      • Should be discarded appropriately after use
    • Drug
      A chemical substance used in the treatment, cure, prevention or diagnosis of disease, or one used to otherwise enhance physical or mental well-being
    • Systemic side effects may arise from the absorption of a drug into the general circulation from conjunctival vessels or from the nasal mucosa after the excess has passed through the lacrimal drainage system
    • Pharmacodynamics
      The effects of the drug on the body
    • Pharmacokinetics
      The way the body affects the drug with time for example, absorption, distribution, metabolism and excretion
    • Receptor
      Interaction sites on cells where drugs bind and produce their effects
    • Reducing absorption of eye drops

      Compressing the lacrimal sac at the medial canthus during, and for 2-3 minutes after instillation of the drops
    • Potential adverse ocular and systemic effects of cyclopentolate hydrochloride
      • Local irritation and stinging
      • Allergic reactions
      • Increased intraocular pressure
      • CNS disturbances
      • Blurred vision
      • Mydriasis
      • Photophobia
      • Drowsiness
    • As the eye has a rich blood supply and small mass it exhibits an unusually high susceptibility to toxic substances. Drug molecules can reach the eye by way of the uveal or retinal vasculature
    • Agonist
      A drug that binds to and activates receptors thereby producing a response
    • Adverse ocular reactions for common drugs
      • Atenolol: Dry eye
      • Aspirin: Subconjunctival haemorrhage
      • Steroids: Cataracts, increased intraocular pressure
      • Vigabatrin: Visual field defects
      • Hydroxychloroquine: Retinopathy, Keratopathy
      • Alendronic acid: Uveitis, scleritis, episcleritis
      • Amiodarone: Keratopathy (corneal deposits)
      • Amitriptyline: Mydriasis, reduced amplitude of accommodation
      • Tamoxifen: Retinopathy, corneal changes, cataracts
      • Tamsulosin: Floppy iris syndrome, blurred vision
    • Partial agonist
      A drug that binds to but only weakly activates receptors
    • Indications for the use of fluorescein
      • Detection of defects in the corneal epithelium
      • Contact lens fitting
      • Applanation tonometry
      • Determination of nasolacrimal duct patency
      • Assessment of tear break up time
      • Tear flow assessment
    • Antagonist
      A drug that binds to but does not activate receptors, and can block the effects of an agonist
    • Rose Bengal
      A vital stain that stains dead or degenerated epithelial cells of the cornea and conjunctiva
    • Ways drugs alter activity at the synapse or neuro-effector junction
      • Reducing or preventing the release of the transmitter substance
      • Promoting the release of the transmitter substance
      • Mimicking the transmitter substance at receptor sites
      • Preventing the breakdown or re-uptake of the transmitter substance
    • Routes of drug administration
      • Enteral (oral, sublingual, rectal)
      • Parenteral (intravenous, intramuscular, subcutaneous, inhalation, epidural, intra-ocular)
    • Legal classifications for drug supply and administration
      • Pharmacy only (P)
      • General sales (GSL)
      • Prescription only medicine (POM)
      • Controlled drug (CD)
    • Common ocular drugs used in optometric practice
      • Mydriatics and cycloplegics (tropicamide, cyclopentolate hydrochloride, phenylephrine hydrochloride)
      • Antibacterials (chloramphenicol, fusidic acid)
      • Topical anaesthetics (tetracaine hydrochloride, lidocaine hydrochloride, oxybuprocaine hydrochloride, proxymetacaine hydrochloride, lydocaine combined with fluorescein sodium)
      • Staining agents (fluorescein sodium, lissamine green, rose bengal)
      • Artificial tears, ocular lubricants, contact lens care products
    • Lissamine Green
      A diagnostic agent that is used to evaluate corneal and conjunctival abnormalities, particularly useful in the investigation of dry eye
    • Light sources used with diagnostic stains
      • Fluorescein: Cobalt Blue Light
      • Rose Bengal: White light
      • Lissamine Green: White Light
    • Wratten no. 12 filter

      Used to enhance the contrast of fluorescein
    • Wratten no. 25 filter

      Used to enhance the staining produced when Lissamine Green is used
    • Fluorescein in Minims form

      Classified and licensed for use as a pharmacy medicine (P)
    • Fluorescein impregnated paper strips

      Unlicensed for use as a medicine in the UK but are CE marked
    • Minims are single dose, preservative-free ophthalmic products designed to reduce the risk of cross-contamination and adverse reactions
    • Minims are supplied in colour-differentiated packaging with Braille labelling to minimise dispensing errors
    • Contamination of fluorescein eye drops is a particularly serious risk as the drops could become infected with bacteria at the time they are being used on damaged tissue which is prone to infection. Sterile impregnated paper strips or sterile single dose units are the safest method of applying fluorescein to the eye
    • Medicines legislation relevant to optometrists and dispensing opticians
      • Medicines Act 1968
      • Prescription Only Medicine (Human Use Order) 1997
      • Medicines (Pharmacy and General Sale- Exemption) Order 1980
      • Medicines (Sale or Supply) (Miscellaneous Provisions) Regulations 1980
      • The Medicines (Exemptions and Miscellaneous Amendments) Order 2009
      • The Medicines for Human Use (Miscellaneous Amendments) (No.2) Regulations 2009
    • Fluorescein impregnated paper strips and Minims are classed as non-hazardous pharmaceutical waste. These need to be incinerated and should be discarded in a medical waste container
    • Fluorescein impregnated paper strips
      Safer method of applying fluorescein to the eye compared to fluorescein in Minims form
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