Week 1- Theophylline + phenytoin

Question 1

what is theophylline?

Answer 1

-its used as a broncho diluter used in asthma and COPD
-causes bronchodilator due to causing phosphdiesterases
-has anti-inflammatory effects

Question 2

when should sampling occur with theophylline?

Answer 2

Sampling:
 IV aminophylline Loading Dose – 4-8 hours post dose
 oral theophylline/aminophylline – pre-dose trough/4-8 hours after last dose

Question 3

what is the adverse drug effects down to?

Answer 3

the different concentrations
-nausea
-insomnia
-diarrhoea

at higher doses- vomiting GI bleeds, seizures

Question 4

what increases the affect of clearance of theophylline?

Answer 4

smoking
enzyme inducers
age 1-16yrs

Question 5

what decreases the affect of clearance of theophylline?

Answer 5

age- ELDERLY
pulmonary oedema
cirrhosis & liver
CCF
VIRAL INFECTION

Question 6

what does phenytoin do?

Answer 6

-stablise rather than raise the seizure threshold

Question 7

how does phenytoin work?

Answer 7

it is highly protien bound but its the unbound that has the pharmacological effect

Question 8

what does the adverse drug reaction come down to when using phenytoin?

Answer 8

to the concentration

Question 9

what are some factors that affect the protein binding of phenytoin?

Answer 9

-Hypoalbuminaemia= which occurs in renal and liver disease
-Hyperbilirubinaemia= as bilirubin competes with phenytoin
-Uraemia
-Acidic drugs =Salicylates, valproic acid

Question 10

how can you increase the amount of free unbound phenytoin?

Answer 10

if theres a decrease in protein binding and a decrease in hepatic metabolism