Bioavailability and dose calculations

Question 1

Measures for assessing bioequivalance

Answer 1

• t_max Time to peak plasma level
• C_max Peak plasma level
• F Bioavailability

Question 2

Some drugs where swapping formulations is not advised due to bioavailability

Answer 2

Carbamazepine: antiepileptic

Lithium: bipolar

Ciclosporin: immunosupressant

Question 3

Different preparations of morphine

Answer 3

T1/2 2-3hrs

Oramorph: oral suspesion, immediate relief

Morphogesic SR: 12hrs

Question 4

Different preparations of nifedipine

Answer 4

DHP calcium channel inhibitor for hypertension and angina

t1/2 = 2hrs

Immediate release formulations associated with increased cardiac events. Should be used as Adalat LA o.d.

Question 5

Which polymers are used in enteric coating

Answer 5

• non-cellulose derivate polymers are used in enteric coating
• Methacrylic acid copolymers
• Contains an acidic functional group

Question 6

Define percentage solutions

Answer 6

Grams per 100 ml of solution

1% = 1m/100ml or 100 mg/10ml

Adrenaline

Lidocaine e.g. 1% is 10mg/ml, a 2ml ampule contains 20mg

Question 7

What is the unit definition for insulin

Answer 7

The quantity required to reduce blood glucose of a fasting rabbit to 2.5mmol/L

Question 8

What is the unit definition for heparin

Answer 8

The quantity required to keep 1ml of cats blood fluid for 24hrs at 0 degrees

Question 9

Drugs that typically come as skin patches

Answer 9

Glyceryl trinitrate

Fentanyl

Formulated with ethanol to enhance penetration

Question 10

Different forms of insulin

Answer 10

Short acting: Soluble rapid onset&duration

Intermediate: Suspesnion with protamine, creates insulin/protein complex b.d.

Long-acting: Cyrstals, high zinc content

Question 11

Depot injection mode of action

Answer 11

• Absorption by use of thick oils that slow down diffusino rate
• avoids first pass metabolism - careful of bioequivalance
• 100% bioavailabilty

If you experience side effects, might take long to clear