Prescribing Flashcards
inappropriate prescribing?
prescribing drugs which are contraindicated
- prescribing drugs with an inappropriate dose or duration
- prescribing drugs which are likely to adversely affect prognosis
- failure to use a drug which could improve a patients outcome
Why is inappropriate prescribing more common in older patients?
1) Older patients have a higher prevalence of chronic disease. 2) Higher levels of polypharmacy (defined as 4 drugs or more) increases the risk of drug-drug and drug-disease interactions 3) Age related changes in physiology, such as altered renal and hepatic function
What happens to pharmacodynamics as we age?
Changes as we age lead to altered (increased or decreased) sensitivity to certain classes of drugs. Increased sensitivity: - BDZs - Opioids - Neuroleptics Decreased sensitivity: - Beta blockers - Beta agonists - Furosemide For example, older patients are less sensitive to propranolol because although the drug binds normally to the receptor, changes to the GPCR second messenger system affect the cells response to the drug.
pharmacokinetics?
Pharmacokinetics is what the body does to the drug. It includes: - absorption - distribution - metabolism - excretion With ageing, metabolism and excretion of many drugs decrease, requiring dose adjustment of some drugs. This is especially important for drugs, with a narrow therapeutic index.
Do changes in drug absorption with age produce any clinically important effects?
No. Age related changes in the GIT are not clinically significant as they do not affect the absorption of most drugs.
How is the distribution of drugs affected by age?
total body fat increases, and therefore increases the volume of distribution for fat soluble drugs. Total body water however, decreases. This decreases the apparent volume of distribution of drugs that are water soluble. Serum albumin also decreases and this INCREASES the affects of albumin bound drugs as the level of unbound drug increases as a consequence
How does hepatic metabolism change with age?
Reduced liver volume and enzyme activity means that hepatic metabolism of many drugs decreases. To prevent toxic accumulation doses must be reduced, or dosing intervals increased.
How is renal elimination affected by age?
Reduction in GFR with age, is important for drugs that are renally excreted. Changes in the GFR decrease the excretion of these drugs. Digoxin is an example of a renally excreted drug with a narrow therapeutic index that often requires a dose reduction as we get older to prevent toxicity.
What is the STOPP START criteria?
This consists of criteria for potentially inappropriate drugs called STOPP (Screening Tool of Older Persons Prescriptions) and criteria for potentially indicated drugs called START (Screening Tool to Alert to Right Treatment).
Give some examples of drugs affecting the cardiovascular system that should be stopped in the elderly as part of the STOPP START guidance
Loop diuretic as first line monotherapy for hypertension CCBs with chronic constipation Use of aspirin + warfarin without stomach protection Use of diltiazam or verapamil with NYHA Class III or IV heart failure
Give some examples of CNS drugs that should be stopped under the STOPP START guidance
TCAs with dementia TCAs with glaucoma TCAs with cardiac conductive abnormalities Long term neuroleptics as long term hypnotics Anticholinergics to treat extrapyramidal side effects of neuroleptic medication
Examples of GIT drugs that may need stopping in accordance with the STOPP START criteria
Diphenoxylate, loperamide or codeine phosphate to treat diarrhoea of unknown cause Prochlorperazine or metoclopramide with Parkinsonism PPI for peptic ulcer disease at therapeutic dose for >8 weeks
Respiratory drugs that may need reviewing as per STOPP START guidance
Theophylline as monotherapy for COPD Systemic corticosteroids instead of inhaled corticosteroids for maintenance therapy in mild-moderate COPD Nebulised ipratropium with glaucoma
What musculoskeletal drugs would you consider stopping in an elderly patient under the STOPP START guidance?
NSAID with a history of peptic ulcer disease or GI bleeding NSAID with moderate-severe hypertension NSAID with heart failure Warfarin and NSAID together
Drugs affecting the urogenital system that you may considering stopping in an elderly patient?
Bladder antimuscarinic drugs and dementia Bladder antimuscarinic drugs and glaucoma Alpha blockers in males with frequent incontinence
Endocrine drugs that may need reviewing in elderly patients
Glibenclamide or chlorpropamide with type 2 diabetes Beta blockers in those with type 2 diabetes and frequent hypoglycaemic episodes - i.e. > 1 per month Oestrogens without progesterone in patients with intact uterus
Name some drugs that are associated with increased falls risk in elderly patients
BZDs (sedative, may cause imbalance) Neuroleptic drugs (may cause gait dyspraxia, Parkinsonism) First generation antihistamines (sedative, may impair sensation)
What cardiovascular drugs would you consider starting in an elderly patient?
Warfarin in the presence of chronic AF Aspirin in AF, where warfarin is contraindicated Aspirin or clopidogrel with a documented history of atherosclerosis is patients with sinus rhythm ACEi in chronic heart failure
What CNS drugs would you consider initiating in elderly patients according to the START criteria?
L-DOPA in idiopathic Parkinson’s disease with definite functional impairment and disability Antidepressant in moderate to severe depressive symptoms lasting at least 3 months
What gastrointestinal drugs should be started in elderly patients as per the START criteria?
Proton pump inhibitor with severe gastro-oesophageal reflux disease or peptic stricture requiring dilatation. Fibre supplement for chronic, symptomatic diverticular disease with constipation.
Respiratory medications that should be started as per the START criteria
Regular inhaled beta 2 agonist or anticholinergic agent for mild to moderate COPD. Regular inhaled corticosteroid for moderate-severe asthma of COPD, where predicted FEV1 is <50%. Home oxygen with documented chronic type 1 respiratory failure (pO2 <8kPa) or type 2 respiratory failure.
What musculoskeletal medication should be given to elderly patients as part of the START criteria?
DMARDs with active moderate-severe rheumatoid disease lasting >12 weeks. Bisphosphonates in patients taking maintenance oral corticosteroid therapy. Calcium and vitamin D supplementation in patients with osteoporosis (radiological evidence or previous fragility fracture).
What anti-emetic is a good alternative to metoclopramide in patients with Parkinson’s disease?
Ondansetron, which is a 5-HT3 receptor antagonist, would be the preferred option.
dementia?
Dementia is a term for a syndrome characterised by acquired global impairment of higher mental functions WITHOUT impairment of consciousness. The key mental functions that are impaired are: - Cognition: memory impairment, speech and language problems, difficult carrying out complex actions (apraxia) such as dressing or somatosensory integration (e.g. differentiating between a toilet and wastebin) - Neuropsychiatric features: character or behavioural changes - ADLs Diagnosis always requires a history of acquired progressive impairment.
