Excretion

Question 1

What are the 5 ways of excretion?

Answer 1

Expired air 
Urine 
Bile 
Sebrum/sweat
Breast milk

Question 2

What 4 drugs are problematic in breastfeeding?

Answer 2

Antithyroid drugs - thyroid suppression in infant
Sulphonamides - haemolytic anaemia
Anticoagulants - coagulation problems
ACEis - profound hypotension

Question 3

If drugs are present in maternal blood, present in milk? Yes/no?

Answer 3

YES

Question 4

for renally impaired, what is an alternative excretion route?
Metabolised drug (AKA metabolites) – major or minor route for bile? Unmetabolised?

Answer 4

Excretion in bile

major route for metabolised drug
minor route for unmet drug

Question 5

Describe enterohepatic recycling in terms of drugs. Good or bad?

Answer 5

Is a possibility in excretion in bile. 
can be good to localise the effects 
consequences:
-prolonged drug action 
-localisation of drug action

Question 6

2 Ways renal secretion happens?

Answer 6

Glomerular filtration

Active secretion

Question 7

What drugs are freely filtered, what drugs aren’t but are still filtered?

Answer 7

All unbound drugs and metabolites are freely filtered

Protein-bound drug isn’t but doesn’t impede excretion bc binding is weak

Question 8

What kind of acids/bases can be actively secreted?

Answer 8

Acids - uric acid, steroid conjugates, penecillins, salicylate, methotrexate, thiazides

Bases - cimetidine and digoxin

Question 9

Explain in terms of interaction between salicylic acid and methotrexate

Answer 9

Salicylate competes with other weak acids for secretion, so excretion of methotrexate is reduced.

Methotrexate and NSAIDs = BAD IDEA

Question 10

Acidic drugs are ionized at what kind of pH? Alkaline drugs?

Answer 10

Acidic drugs ionised at alkaline pH

Alkaline drugs ionised at acid pH

Question 11

Can lipid-soluble drugs be reabsorbed?

Answer 11

Yes, barrier is lipid bilayer so lipid soluble drugs can pass back and be reabsorbed

Question 12

why should you be cautious about drug dosage for infants and elderly?

Answer 12

Renal function inefficient in newborn infants (plus inefficient drug met)

By 80 yrs, renal function only 50% of a young adult

Question 13

What are 3 ways to work around renal impairment?

Answer 13

Approaches:

• choose SHORT ACTING AGENTS
• increase dosage interval
• choose non-renally excreted alternatives

Question 14

1 drug to avoid in renal impairment?

Answer 14

METFORMIN (for type II diabetes)

Question 15

1 drug to ineffective in renal impairment?

Answer 15

thiazide diuretics

Question 16

how is loading dose affected in renal impairment?

Answer 16

not affected