Exercise - Drug Interactions Flashcards
What physiological changes with exercise can influence pharmacokinetics?
redistribution of blood flow - away from gut and kidney and towards muscles and skin, increased muscle mass, altered skin temperature (bioavailability for topical drugs), increased resp rate (impacts bioavailability of inhaled drugs), decreased gastric emptying (will either decrease or increase bioavailability depend on the drug), decreased intestinal transit time (less time to be absorbed), loss of water from plasma (drugs which bind to carrier proteins), alter metabolic enzyme activity (after chronic exercise)
How does decreased hepatic flow in exercise alter pharmacokinetics?
decreased metabolism
How does decreased renal blood flow in exercise alter pharmacokinetics?
decreased excretion
What is the impact of exercise on plasma insulin?
exercise - increased plasma insulin - risk of hypoglycaemia
What are some considerations for prescribing exercise and insulin?
type of insulin, proximity of insulin injection to limbs, type duration and intensity of exercise, amount of muscle mass, level of fitness, pre exercise glucose levels, whether they are taking carbohydrate supplementation
What is the mechanism of exercise induced hypoglycaemia?
accelerated insulin absorption from sites near exercising muscle, exercise mediated enhancement of insulin action, lack of decline in insulin secretion during exercise
What is the mechanism of exercise induced hyperglycaemia?
excessive carbohydrate supplementation, too large a reduction in insulin dose
What is the impact of exercise on GTN?
if GTN is being taken transdermally for prophylaxis then exercise will increase skin temperatures and improve absorption - this may be beneficial for the angina but may also be detrimental if get excessive hypotension and diversion of coronary blood flow
What is the impact of exercise on salbutamol?
exercise will caused an increase resp rate, increased pulmonary blood flow and will open epithelial junctions - this will lead to increased plasma levels which could provide benefit but the down side is it will wear off more quickly because of the increased resp rate
What is the impact of exercise on lipophilic drugs?
exercise will decrease intestinal transit time so there will be less absorption of lipophilic drugs
What is the impact of exercise on warfarin?
in exercise warfarin has increased binding to albumin so will have less effect and with training the metabolism of warfarin increases - this will lead to a lower INR which increases risk of thrombosis
What is the impact of exercise on digoxin?
reduced plasma concentration because of increased binding in skeletal muscle so it has less ability to impact on cardiac contractility and rate
What is the impact of exercise on propanolol?
propanolol is highly reliant on hepatic clearance - so the decreased hepatic blow flow in exercise will cause decreased hepatic clearance so increased effect - this will result in bronchoconstriction and an inability to raise heart rate high enough
What is the impact of exercise on atenolol?
atenolol is highly reliant on renal clearance so the decreased renal blood flow will cause decreased renal clearance so increased effect - this will result in bronchoconstriction and an inability to raise heart rate high enough
What are the criteria for a substance to be prohibited?
potential to enhance or does enhance performances, poses a risk to athletes health, violates the spirit of the sport
What is a therapeutic use exemption?
for athletes who suffer medical conditions that a doctor can only treat with a prohibited substance the athlete can get an exemption but only if they receive approval before using the drug
What are the reasons someone would take a diuretic in sport?
weight loss, mask other drugs
What are the disadvantages of a diuretic?
dehydration, hypokalaemia
What are the potential advantages of beta blockers in sport?
reduce heart rate and stress, stop shaking in sports that require accuracy
What are the disadvantages of beta blockers in sport?
can’t increase blood pressure and heart rate, less blood flow to muscles and skin, increased fatigue
What are the potential advantages of beta 2 agonists in sport when used systemically?
increased skeletal muscle blood flow, anabolic effects to increase muscle mass, catabolic effects to decrease body fat
What are the disadvantages of beta 2 agonists in sport?
tachycardia, muscle tremor
What are the potential advantages of glucocorticosteroids in sport?
mask pain
What are the potential disadvantages of glucocorticosteroids in sport?
damage to tissues, osteoporosis, growth suppression, skin fragility, increased infections
What are the potential advantages of synthetic testosterone in sport?
increase muscle strength by encouraging new growth
What are the potential disadvantages of synthetic testosterone use in sport?
high blood pressure, dislipidaemia, jaundice, liver damage, mood swings, depression, aggression, acne, baldness, breast development, infertility, hirsuitism, menstrual cycle disruption
What are the potential advantages of growth hormone in sport?
reduced fat mass, increased lean mass, increased bone density
What are the potential disadvantages of growth hormone in sport?
joint pain, increased risk of diabetes, acromegaly
Why is AOD9604 banned?
because any drug that is not currently approved for human use is prohibited at all times
What are the potential benefits of AOD9604 in sport?
increased lipolysis, repair or cartilage and muscle and joint disorders
What are the potential disadvantages of AOD9604?
headache, chest tightness, palpitations, euphoric feelings
