BIOL205 Lecture 2: What Is a Drug? PDF

BIOL205 Lecture 2: What is a drug? Tanya Uebergang (PhD)  WARNING This material has been reproduced and communicated to you by or on behalf of Australian Catholic University in accordance with section 113P of the Copyright Act 1968 (Act). The material in this com...

BIOL205 Lecture 2: What is a drug? Tanya Uebergang (PhD)  WARNING This material has been reproduced and communicated to you by or on behalf of Australian Catholic University in accordance with section 113P of the Copyright Act 1968 (Act). The material in this communication may be subject to copyright under the Act. Any further reproduction or communication of this material by you may be the subject of copyright protection under the Act. Do not remove this notice What is Pharmacology? Definition study of drugs (Greek word pharmakon) actions and effects on living systems What is a drug? WHO definition of a drug ‘any substance or product that is used or intended to be used to modify or explore physiological systems or pathological states for the benefit of the recipient’ any substance that acts on living tissue What is a medicine? drug mixed in a formulation to allow it to be administered To administer a drug safely: well informed about each medication For example: how the drug works (pharmacodynamics) how our body affects the drug (pharmacokinetics) usual dose, frequency and route of drug administration pharmacological effects and indications adverse drug effects and contraindications drug interactions Useful drug characteristics Potency amount of chemical required to produce an effect Selectivity (biological) narrowness of a drug’s range of actions on particular receptors, cellular processes or tissues Specificity (chemical) relationship between chemical structure of drug and pharmacological effects Is alcohol an ideal drug? Lorazepam Ethanol (benzodiazepine) (alcohol) Route of administration Oral Oral Absorption Well absorbed Diffuses through lipid membranes Potency 20-30 ng/ml 0.5-5 mg/ml Dose 1-4 mg 5-20 g (average drink) Selectivity Facilitates an inhibitory NT Depresses neuronal activity (GABA) binding to its receptor Specificity High (closely related to all Low benzodiazepines) Drug interactions Many prescription and OTC Many prescription and OTC drugs drugs Some characteristics to consider: Is it easy to administer? Is it well absorbed? Is it potent? Is it highly selective? Is it highly specific? Does it interact with other drugs? What other characteristics should be considered? Sources of drugs micro-organisms eg) fungi as a source of antibiotics humans and other animals eg) adrenaline minerals or mineral products eg) iron substances synthesised in laboratories eg) anti-depressants plants eg) caffeine, cocaine, morphine, digoxin Drug names 1) chemical eg) 7-chloro-1,2-dihydro-1-methyl-5-phenyl-2H-1,4-benzodiazepin-2-one 2) approved (‘generic’) also called non-proprietary or “generic” active ingredient eg) diazepam 3) trade proprietary or brand name eg) Valium What is the approved (generic; active ingredient) name? Amoxil® Ventolin® Implanon NTX® Lipitor® Advil® Panadeine Forte® versus Generic prescribing an additional brand of an existing medicine contains same active ingredient can be manufactured and sold by other pharmaceutical companies once the patent for the existing brand has expired generic medicines account for 40% of prescriptions filled by the Pharmaceutical Benefits Scheme (PBS) (NPS, 2011) Therapeutic Goods Administration (TGA) requires that generic medicines meet the same quality criteria and manufacturing standards as the original brands Bioequivalence bioequivalence refers to whether the generic medicine releases the active ingredient into the bloodstream at the same rate and to the same extent as the original medicine bioequivalence is demonstrated by conducting a bioavailability study TGA requires evidence of bioequivalence Drug Classifications therapeutic use eg) antidepressant mechanism of action eg) monoamine oxidase inhibitor molecular structure eg) tricyclic antidepressant system affected eg) CNS depressant drug schedule eg) S8 pregnancy safety eg) A, B1, B2, B3, C, D, X https://www.tga.gov.au/australian-categorisation-system-prescribing-medicines-pregnancy Drug schedules Schedule Type of medicine Example classification Schedule 2 pharmacy only medicine large packet sizes of paracetamol Schedule 3 pharmacist only topical thrush medicine treatments Schedule 4 prescription only blood pressure medicine medications Schedule 8 controlled drug – S8 has strong additional restrictions on analgesics the storage and supply of medicines Over-the counter (OTC) medicines medicines that are not prescription medicines medicines that are not complementary medicines considered to be lower risk than prescription medicines Pillar 3 of the National Medicine Policy (NMP) Quality Use of Medicines Selecting treatment options Choosing suitable medicines Using medicines safely and effectively Drug information sources Australian Pharmaceutical Formulary and Handbook Therapeutic Guidelines Limited Cochrane databases MIMs (ACU Library/Databases/MIMs online) Therapeutic Goods Administration National Prescribing Service Australian Prescriber References Australian Government. Generic prescription medicines: Fact Sheet https://www.tga.gov.au/news/news/generic-prescription-medicines-fact-sheet Australian Government. National Medicines Policy https://www.health.gov.au/resources/publications/national-medicines-policy?language=en Australian Government. The regulation of over-the-counter medicines https://www.tga.gov.au/australian-regulation-over-counter-medicines Bullock, S. & Manias, E. (2022) Fundamentals of Pharmacology. 9th ed. Pearson. Knights, K., Darroch, S., Rowland, A., and Bushell, M. (2023) Pharmacology for Health Professionals. 6th ed. Elsevier. McLachlan, A. J. (2010). Generic medicines literacy — minimising the potential for patient confusion. Medical Journal of Australia, 192(7), 368–369. https://doi.org/10.5694/j.1326- 5377.2010.tb03555.x Ritter, J., Flower, R., Henderson, G., Loke, Y., MacEwan, D., Robinson, E. & Fullerton, J. (2023) Rang and Dale’s Pharmacology. 10th ed. Churchill Livingston