Introduction to Pharmacology - Dr Wai Ling Kok (2023-24).pptx

Introduction to pharmacology Dr Wai Ling Kok Acknowledgement: Dr Zoë Brookes Learning Objectives At the end of this session, students should be able to: Define basic pharmacological concepts underpinning the mechanisms of action of all drugs Report on how to appropriately prescribe and administer dr...

Introduction to pharmacology Dr Wai Ling Kok Acknowledgement: Dr Zoë Brookes Learning Objectives At the end of this session, students should be able to: Define basic pharmacological concepts underpinning the mechanisms of action of all drugs Report on how to appropriately prescribe and administer drugs and therapeutic agents Recognise drugs prescribed in dentistry Pharmacology Pharmacology: study of the actions, mechanisms, uses and adverse effects of drugs Drug - any natural or synthetic substance that causes an altered (physiological) response in a living organism  Medicinal drugs: (prescribed and not prescribed): prevention or treatment of disease or unwanted symptoms e.g. paracetamol, penicillin  Nonmedicinal drugs: recreational purposes; some illegal e.g. cannabis, heroin and cocaine, others legal e.g. caffeine, nicotine and alcohol Pharmacology – receptors Most drugs produce their effects by acting on specific protein molecules called receptors (usually in the cell membrane) Drugs can also inhibit enzymes, ion channels and transporter molecules Some drugs directly interact with molecular targets found in pathogens Pharmacology – receptors Receptors respond to endogenous chemicals (ligand or drugs) in the body that are either: - Synaptic transmitter substances/neurotransmitters, e.g. ACh, noradrenaline, dopamine - Hormones (endocrine) e.g. insulin; or local mediators, e.g. histamine Neurotransmitters: released from nerve terminals that diffuse across the synaptic cleft, and bind to presynaptic or postsynaptic receptors Hormones: released locally, or into the bloodstream from specialized cells, can act at neighbouring or distant cells Pharmacology – receptors Pharmacology – receptors 1. Receptors directly linked to ion channels Receptors may open or close the ion channel Mainly involved fast synaptic neurotransmission - Acetylcholine (ACh) receptors = Na+ and K+ ions - GABAA and glycine receptors = Cl- and some HCO3 ions Pharmacology – receptors Pharmacology – receptors 2. G-protein–linked receptors Occupation of receptor by agonist produces a conformational change Instigates intracellular signalling pathways Relatively fast transduction E.g. muscarinic / nicotinic ACh, adrenergic α and β (noradrenaline, adrenaline), dopamine, serotonin and opiate receptors Pharmacology – receptors Inactive state Active state Pharmacology – receptors 3. Tyrosine kinase-linked receptors Involved in the regulation of growth and differentiation, and responses to metabolic signals, e.g. growth factors such as VEGF 4. Deoxyribonucleic acid–linked receptors Located intracellularly, so agonists must pass through the cell membrane to reach the receptor, e.g. steroids, thyroid hormones Pharmacology – receptors Agonists: ligands (drugs) activate receptors and produce a subsequent response Antagonists: ligands (drug) associate with receptors but do not cause activation or response Antagonists inhibit the physiological response of agonists (natural or synthetic) Prescribing Drugs are taken to prevent or alleviate symptoms of disease May be antagonist or antagonists, ideally specific All drugs have side effects Some drugs have pleiotropic effects Prescribing There are three classes of medicinal drugs available: – General Sales List Medicines (GSL) – Prescription only Medicines (POM) – Pharmacy Medicines POMs can only be prescribed by: – Doctors – Dentists – Pharmacists – Nurse Practitioners With a prescription, registered pharmacists then supplies specified drugs to the patient Prescribing and the Law Prescribing is governed by a number of regulations made under the: – – – – – The Medicines Act of 1968 The Misuse of Drugs Act 1971 The Misuse of Drugs Regulations 2001 The NHS Act 1977 The National Health Service Regulations for NHS patients Over-the-counter medicines (OTMs) Cheaper to buy over the counter e.g. paracetamol, ibuprofen or aspirin Prescribing these drugs is costly to the NHS Pharmacists can also advise on OTCs indications (reasons to use) and contraindications – may be first line Check for content with trade names Prescribing - General Guidance Always review medical history, underlying disease and other medications may cause an altered or unwanted reaction Prescribe only the minimal dose/duration to meet the patient’s need Prescribe only when necessary, look for alternatives All drugs have side effects therefore benefit > risk Always make patients aware of side effects and importance of adhering to recommended dose/duration Some drugs contraindicated during pregnancy Doses of drugs change in the very young and very old Prescribing – considerations Medical conditions – – – – – Allergies Renal Disease Liver Disease Anticoagulants Concurrent medications Pregnancy and breastfeeding Age – Children – Elderly Prescribing - pregnancy and breast feeding Some drugs clear teratogenic links e.g. thalidomide, tetracycline However, no drug is absolutely safe Risk < benefit During breastfeeding drugs still can affect baby via maternal milk Consult the BNF and seek advice from GP if required Prescribing - Elderly Complicated by the physical and mental changes that accompany old age - Swallowing - Complex regimens more difficult - Altered renal and liver function Polypharmacy - Drug interactions Doses - Dosages should be lower than for younger patient; start with about 50% of the adult dose (see BNF) Prescribing - Children Compliance more challenging, may not be able to swallow tablets - Liquid preparations - Sugar-free Do not add medicines to infant’s feed - May interact with milk or other liquids - Child may not finish meal Doses - Dosages should be lower for the child patient and are age specific, particularly under 12 years old (see BNF) Keep POMs out of the reach of children – all drugs toxic at high doses The British National Formulary Complied by a panel of experts and is updated every 6 months (BNFC annually) It is available in print format & online List of drugs prescribed by NHS dentists under the Dental Practitioners Formulary – please visit this site The British National Formulary The BNF details all medicines prescribed in the UK – – – – – – – – Indications Contra-indications Cautions Side effects Dosage Preparations Interaction with other medication Cost Dental Prescriptions NHS Form FP10 D (Eng & Wales) (yellow) (GP14 in Scotland) (WP10D in Wales) (HS47 in Northern Ireland) Restricted to those that appear on the Dental Practitioners’ Formulary ‘How to write a prescription’ – Year 2 BDS DTH do not prescribe, but need to understand medical histories and pharmacology Common abbreviations used on prescriptions IM – intramuscular injection IV – intravenous injection SC – subcutaneous injection Mane – in the morning Nocte – in the evening bd- twice a day tds – three times a day qds – four times a day Rarely used, may cause confusion Common prescription drugs dentistry Local anaesthetics – lidocaine, articaine, mepivacaine Antibiotics – amoxicillin, metronidazole, penicillin, erythromycin, tetracycline, doxycycline Antifungals – miconazole cream or gel; nystatin oral suspension Artificial Saliva Substitutes Mouthwashes – benzydamine (NSAID) Oral sedation (diazepam tablets) Other common non-prescription drugs dentistry Pain and inflammation Ibuprofen (Advil, Nuprin, Motrin), Paracetamol /acetaminophen (Tylenol, Disprol – soluble) Aspirin (Anadin – various combinations) Paracetamol & codeine (Solpadeine) Local pain Lidocaine, benzocaine (oral ulceration, e.g. Bonjela Junior, Anbesol, Orabase) Corticosteroids (oral ulceration, e.g. Orabase-HCA) Mouthwashes Chlorhexidine (Corsodyl), Hydrogen peroxide (Peroxyl) Common drugs on patient medical histories Cholesterol-lowering drugs: atorvastatin, simvastatin Hypothyroidism: hormone levothyroxine Gastro-oesophageal reflux disease (GORD) - Proton Pump Inhibitors (PPIs): omeprazole, lansoprazole High blood pressure drugs: amlodipine, ramipril Heart failure, angina: bisoprolol Anti-diabetic drugs: metformin Asthma: Salbutamol, beclametasone Painkillers: paracetamol, ibuprofen, codeine, gabapentin Depression: sertraline, citalopram Year 2 Pharmacology Drug names On prescriptions write generic names…. Non-proprietary Titles (generic names) Proprietary Titles (trade names) However, need to be aware of both…. Drug names Jantoven, Coumadin = ??? Tylenol = ??? Lipitor = ??? Drug names Jantoven, Coumadin = warfarin Tylenol = paracetamol Lipitor = atorvastatin Some general rules ….olol = beta blocker; ….pril = ACE inhibitors (blood pressure); ….oxetine = antidepressants;.…vastatin = HMCoA inhibitors (statins, cholesterol) https://en.wikipedia.org/wiki/Drug_nomenclature Summary You should now understand that drugs act on receptors to initiate physiological responses, including ions channels, G-protein linked, tyrosine kinase linked (all in the cell membrane) and DNA nuclear receptors You should know that an agonist activates a receptor and an antagonist inhibits it You should have a basic understanding of the considerations of prescribing, as a foundation for learning how to write a prescription in BDS2 or understanding medical histories DTH2 You should be able to recognise the names of some of the drugs prescribed in dentistry and found on patients medical histories so that you can explore their mechanisms of action in BDS2 and DTH2 Reading list/references Medical Pharmacology at a Glance – Year 1 Rang and Dale’s Pharmacology –Year 2 BNF – prescribing in England Drug Prescribing for Dentistry 3rd edition Scottish Dental Clinical Effectiveness Programme (SDCEP), January 2016 Dental School > Programme information > Core Reading List > Leganto Reading List > Pharmacology