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Prescribing in general practice

  • Most common management activity in general practice

Aims of tutorial

  • What should be considered with prescription
  • Medicines review
  • Where to find out information

Qualirty use of medicines

  1. Selecting management options wisely
  2. Choosing suitable medicines if a medicine is considered necessary
  3. Monitoring, safety

Regulation

  • Commonwealth government
    • TGA
    • PBS, RPBS
    • Medicare Australia
  • State government
    • Poisons schedule
      • S2, S3, S4, S8
      • S8 = drugs of addiction
      • S4 = by prescription; doc or vet
      • S3 = pharmacist needs to oversee handing out of drug
      • S2 = available at supermarkets (paracetamol)
  • http://www.humanservices.gov.au

PBS/RPBS

  • Schedule of pharmaceutical benefits
  • Example: alprazolam (Xanax); benzo
    • Panic disorder where other treatments have failed or are inappropriate
  • Safety net - when you get to a particularly sum of health expenditure, things won't cost as much (no one loses their house due to illness)
  • Maximum price to consumer is due to pharmacy markups
  • Two types of patients - general and concessional
  • Patient contribution - $35.40 for general patients, $5.80 for concession patients
    • The difference is paid by the taxpayer
  • Safety net threshold
    • General patients - $1363.30
    • Concessional patients - $348.00
      • Use increases just before the next calendar year due to squirrelling of free meds

Some extra complications (What do these mean?)

  • Generic substitution
    • e.g. patent expires; price drops due to generics; equivalent to original drug in performance; bioavailability and blood profile is exactly the same
    • they check generic drugs by giving them to a group of people and checking the profile in the blood
    • in practice you should prescribe generically
      • unless you tick 'no brand substitution', the pharmacist can change to the generics. Only grounds is 1) patient requests just one brand 2) allergy to fillers in generics 3) worried about confusion
  • Brand price premium - originator drug company charges more money (e.g. lercanidipine)
  • Therapeutic group premium
    • E.g. candesartan company tells the govt. that this one a2 blocker is better than the others; PBS doesn't agree with the evidence, so the consumer must pay not the taxpayer
  • Restricted benefit indication
  • Authority prescription
  • Clopidogrel = aspirin + clopidogrel = platelet antithrombotic for post-MI
    • Treatment of acute coronary syndrome (myocardial infarction or unstable angina)
    • Treatment following cardiac stent insertion
    • Prevention of recurrence of myocardial infarction or unstable angina in patients with a history of symptomatic cardiac ischaemic events while on therapy with low-dose aspirin
  • Streamlined authority - put the number on the script so that someone doesn't need to check your PBS prescription
    • Relies on trust - that you have checked that this person follows the criteria

Access to prescription medicines in Australia

  • Pharmaceutical Benefits scheme

Past notes

PRESCRIBING IN GENERAL PRACTICE

  • Most common management activity in GP
  • Medication prescribed in 84% of encounters
  • Prescribed for 58% of problems

AIMS OF TUTORIAL

  • What should be considered when contemplating writing a prescription
  • Review in the medications your patient is taking
  • Finding out answers to questions about medicines

WHAT SHOULD BE COSNIDERED QUM

  • Key focus of QUM is
    • Selecting management options wisely
    • Choosing suitable medicines if a medicine is considered necessary
    • Using medicines safely and effectively

HOW ARE MEDICINES REGISTERED LISTED, AND REGULATED

  • Commonwealth government
    • TGA
    • PBS, RPBS (re-patrions for veterans)
    • Medicare Australia
  • State government
    • Poisons schedule
      • S2, S3, S4, S8
      • If you have a drug – various categories
      • S4 = prescription
      • S3 = pharmacist medicine
      • S8 = drugs of addiction
      • S2 = what you can find in supermarkets → paracetamol

PBS/RPBS

  • Schedule of Pharmaceutical Benefits
    • Website has stuff and info about the prescription drug, under section for PBS prescribers
  • Two types of patients – general and concessional
  • Patient contribution - $35.40 for general patients, $5.80 for ‘concession’ patients
  • Safety net thresholds
    • General patients - $1363.30
      • After this, individuals pay at the concession rate ($5.80)
    • Concessional patients - $348
      • After this, patients pay nothing

SOME COMPLICATIONS

  • Generic substitution
  • Brand price premium
  • Therapeutic group premium
  • Restricted benefit indication
    • If a drug is very expensive, need to get it approved etc.
  • Authority prescription
    • Highest level → need an application for this drug

ACCESS TO PRESCRIPTION MEDICINES IN AUSTRALIA

  • PBS
    • Unrestricted benefits
      • General patients - $35.40
      • Concessional patients - $5.80
  • Private access
    • List price

WHAT TO CONSIDER WHEN PRESCRIBING

  • Select management options wisely
    • What are the problems, what is the pathophysiology
    • Are medicines needed
  • Choosing suitable medicines
  • Individualised therapy

RELIABLESOURCES OF INFORMATION

  • AMH
  • Therapeutic Guidelines
  • National Prescribing Service
  • Product Information - MIMs
  • Consumer Medicines Information (CMI)

CaseStudyPrescrip.png

  • INDOCID
    • Indomethacin – NSAIDs
  • Complains of
    • Dizziness – hypotension
    • Swelling of legs – Ca+ channel blockers
  • Postural hypotension
    • Standing for 1min
      • Systolic drop of 20
      • Diastolic drop of 10
  • Meds
    • Amlodipine/Zanidip – L calcium channel blocker - antihypertensive
      • Relaxes smooth muscle in the arterial wall → decreases total peripheral resistance
      • Side effects
        • Hypotension (postural)
        • Dizziness
        • Light headedness
        • Flushing, swelling of ankles, headache
      • Cost - $15.35 – 20.50 (Les pays $5.80)
      • No known interactions
      • BP every 6 months
    • Atorvastatin – statin – anti-cholesterol
      • Inhibits HMG-CoA reductase – enzyme found in liver involved with cholesterol production
      • Side effects
        • Flushing
        • Insomnia
        • Headache
        • Diarrhoea
        • Constipation
        • Creatinine phosphokinase increases - pain on exercise
      • Monitor LFT pre, 3/12 post, every 6/12, cholesterol
      • Cost - $35.40 (Les pays $5.80)
      • No reactions
      • Restricted benefit - for cardiovascular disease (stroke/MI)
    • Tegretol /carbamazepine – anti-convulsant - sodium channel blocker
      • Side effects
        • Drowsiness, headaches, migraines, upset stomach
      • Cost - $32.06-37.21 (for him; $5.80 plus $2.96 which is brand price premium)
      • Note that it increases metabolism
      • Restricted benefit - no restrictions
      • Trigeminal neuralgia (can cause suicide) or general schedule epilepsy
      • Check: blood conc. when stable, FBC, skin
    • Iscover/clopidogrel – anti-platelet (blocks P2Y12 receptor on platelet)
      • Inhibits clotting affects in coronary artery disease, peripheral vascular disease and cerebrovascular disease
      • Prevent stroke, previous ischaemic stroke and AF
      • Secondary prevention of ischaemic stroke in patients at risk of bleeding
      • Side effects
        • Neutropenia
        • Haemorrhage
        • GIT symptoms – diarrhoea
      • Cost - $35.40 – 50.15 ($5.80 on Authority; $57.53 if private)
    • Gabapentin – anti-epileptic and neuropathic pain
      • Side effects
        • Dizziness
        • Fatigue
        • Weight gain
        • Drowsiness
      • Cost - $35.40 – 45.19 ($5.80 on Authority; $59.23 if Private)
      • Check pain scale and renal function
    • Moclobemide – MAOI
      • Side effect
        • Hypotension
        • Rash – pruritis
        • Diarrhoea
      • Cost - $24.77 – 29.92 ($5.80 plus $1.37 brand price premium)
      • Check for mood relapse
    • Ramipril – ACEI
      • Inhibits angiotensin converting enzyme
      • Side effects
        • Low sugar
        • Dry cough
        • Fainting
        • Hypotension
        • Fatigue
        • Dizziness
      • Cost - $16.50 - $21.65 ($5.80)
      • Check BP
    • Sotalol – anti-arrhythmic
      • Non-selective beta-blocker
      • Used for AF, ventricular tachycardia
      • Prolongs PR and QT interval
      • Side effects
        • Dizziness
        • Headache
        • Diarrhoea
      • Cost - $20.12-30.27
      • Check BP, pulse

Usually you need 2 or more drugs for hypertension.