Transfer of Drugs Across Biological Membranes

Question 1

mg/mL in 1% Solution

mg/mL in 1:1000 Solution

Answer 1

10 mg/mL in 1% Solution

1 mg/mL in 1:1000 Solution

Question 2

A patient with COPD is treated with tiotropium with capsules containing 18 micrograms each.
What quantity of drug is contained in 60 capsules?

Answer 2

1080mcg/1.08mg

Question 3

May be expressed per body weight or a standard adult dose.
Aminophylline is used at 500 micrograms per kg per hour (and then adjusted accorded to monitoring)
How much aminophylline is required for a 76kg man?

Answer 3

38mg/hr

Question 4

Aminophylline is supplied as 25 mg/mL
1 mL is dissolved in 200 mL
What rate would you infuse it?

(38mg/hr)

Answer 4

304 ml/hour

Question 5

A patient requires an infusion of a general anaesthetic.
Dose rate = 5 mg/kg/hour
GA supplied as a 50 mg/mL solution

What is the infusion rate for a 76 kg man?

Answer 5

7.6ml/hour

Question 6

A 76kg man with endocarditis is to receive gentamicin by intra-muscular injection. The recommended dose is 1 mg/kg every 8 hours.

The gentamicin is available at a concentration of 40 mg/ml in a 2ml ampoule.

Q: What volume needs to be administered?

Answer 6

1.9ml

Question 7

Following a stroke a patient is infused with alteplase.
900 microgram/kg over 60 mins, with 10% of the total dose given initially.
Solution is 10 mg/mL

For a 67kg patient:
What is the initial dose (mg)?

Answer 7

6.03mg

Question 8

Following a stroke a patient is infused with alteplase.
900 microgram/kg over 60 mins, with 10% of the total dose given initially.
Solution is 10 mg/mL

For a 67kg patient:
Subsequent infusion rate (mL/min)?

Answer 8

0.09045mL/min

Question 9

Drugs expressed as percentages/ratios

Answer 9

Local anaesthetics
Adrenaline
Some eye drops

Question 10

Lidocaine: an anti-arrhythmic and local anaesthetic
Supplied as 1 or 2 % solutions
1 % is ? mg/ml
A 2 ml ampoule contains ? Mg
A 10 ml syringe contains ? Mg
2 % is ? mg/ml
A 2 ml ampoule contains ? Mg
A 5 ml ampoule contains ? Mg

Answer 10

1 % is ? mg/ml - 10
A 2 ml ampoule contains ? Mg - 20
A 10 ml syringe contains ? Mg - 100

2 % is ? mg/ml - 20
A 2 ml ampoule contains ? Mg - 40
A 5 ml ampoule contains ? Mg - 100

Question 11

Bupivacaine: a local anaesthetic
Supplied as 0.25% or 0.5 % solutions
0.25 % is ? mg/ml
A 10 ml ampoule contains ? mg

0.5 % is ? mg/ml
A 5 ml ampoule contains ? mg

Answer 11

0.25 % is ? mg/ml – 2.5
A 10 ml ampoule contains ? Mg - 25
0.5 % is ? mg/ml - 5
A 5 ml ampoule contains ? mg - 25

Question 12

You need to give 100 mg loading dose of lidocaine (1% solution)
What volume do you inject?

Followed by 4 mg/min infusion for 30 mins
What is the infusion rate (per hour)

Answer 12

You need to give 100 mg loading dose of lidocaine (1% solution)
What volume do you inject? – 10ml

Followed by 4 mg/min infusion for 30 mins
What is the infusion rate (per hour)
0.4mL/min – 24mL/hour

Question 13

The BNF specifies an intramuscular injection of 250 micrograms to treat anaphylactic shock in children aged 6-12 years. What volume would be needed?
1:1000

Answer 13

0.25mL