Prescribing in Elderly Flashcards
What environment do drugs require for absorption?
Acidic drugs require acidic environment
Basic drugs require basic environment
Why is drug absorption different in older people?
Increased gastric pH and decreased small bowel surface area
What are some issues that may present in older people that may affect absorption?
Previous GI surgery, NJ tube or PEG feed composition, transdermal patches and oedema, proportionally more of basic drugs absorbed
How may route of drug delivery need to be changed in an older person?
Liquid/syrup for dysphagia, crush tablets for PEG or NG tube, confused patients may refuse tablets
What do drugs bind to in the body?
Albumin binds to acidic drugs and alpha-1 acid glycoprotein binds to basic drugs = older people have low albumin but higher a-1 AG
How is drug distribution different in older people?
Increased fat = increases Vd of lipophilic drugs increasing half life
Decreased body water by 10-15% = lower Vd of hydrophilic drugs
Lower Vd and CrCL so half life unchanged
How is hepatic drug metabolism different in older people?
Reduced liver function due to decreased size and blood flow = first pass metabolism reduced, biotransforming enzymes reduced
How is renal drug metabolism different in older people?
Lower GFR = decreased size, tubular secretion and renal blood flow
How are pharmacodynamics different in older people?
Lower doses achieve same effect
Some effects are decreased (e.g B blockers)
What drugs should be used with caution in older people?
Those with therapeutic index <2 = theophylline, warfarin, lithium, digoxin, vancomycin, gentamicin
What are some drugs that commonly cause side effects?
Warfarin, digoxin, insulin, benzodiazepines, diuretics, NSAIDs, corticosteroids, antihypertensives, opioids, theophylline
What are some ways to manage risk of side effects of certain drugs?
Opioids = begin laxative prophylactically Steroids = osteoporosis prevention if long term Levothyroxine = remember calcium interferes with absorption
What are some side effects of NSAIDs?
GI haemorrhage, decline in GFR, decreased effectiveness of diuretics and antihypertensives
What are some side effects of opioids and benzodiazepines?
Impair psychomotor function = falls and confusion
What are some side effects of antibiotics?
Resistance and C.diff diarrhoea
What are some examples of older people who may be at risk of complications?
Recent hospital discharges and use of multiple drugs
Change in patient condition and multiple prescribers
Impaired cognitive status or communication issues
What types of medications are associated with increased risk of complications in older people?
OTC, complementary medicine, drugs with narrow therapeutic index, drugs associated with side effects
How common is polypharmacy?
Average use for patient >65 = 4 prescription drugs and 2.5 OTC medications
Average nursing home patient on 7 medications
How can polypharmacy be avoided?
Try to avoid treating side effect of drug with another drug and try to prescribe a drug that will treat more than one existing problem
What is Beers criteria of medication?
List of >50 medications split into three categories
What are the categories in the Beers criteria?
A = always avoided B = potentially inappropriate C = use with caution
What is the disadvantage of the Beers criteria?
issues with use in UK as >50% of drugs are not available in Europe
What are the components of the STOPP-START tool for prescribing?
STOPP = screening tool for older people's potentially inappropriate prescriptions START = screening tool to alert doctors to right treatment
What is the purpose of the STOPP-START tool for prescribing?
Highlights prescriptions that are potentially inappropriate if age >=65 and those that should be considered if there are no contraindications
What are some GI medications that should be stopped in older people?
Loperamide, prochlorperazine/metoclopramide in Parkinsonism, stimulant laxatives for intestinal obstruction
What are some GI medications that should be considered in older people?
PPI for severe GORD or patients >80 on antiplatelets and SSRIs, fibre supplement for chronic symptomatic diverticular disease
What are some CV medications that should be stopped in older people?
B-blockers with verapamil, non-selective B-blockers in COPD, CCB in chronic constipation or class 3/4 heart failure, dipyridamole, atorvastatin 80mg for >6 months post MI
What are some CV medications that should be considered in older people?
Antihypertensives where SBP >160 mmHg, ACEi in chronic heart failure or post MI, PPI with aspirin and warfarin, warfarin in chronic AF
