Several oral medicines that are used in the management of neuropathic pain require dose titration. This month's calculation skills ask you to calculate the total quantities of medicines that would need to be prescribed for these scenarios:
QUESTION 1
Sean wants to prescribe pregabalin for his patient with neuropathic pain. He wants to start with 75 mg twice daily for 7 days, then increase the dose to 150 mg twice daily. He will be reviewing his patient after 4 weeks.
How many 75 mg capsules should be prescribed for 4 weeks?
QUESTION 2
Gill wants to prescribe gabapentin for her patient, a 42-year-old male. She checks the Summary of Product Characteristics and finds the following dosage advice:
For all indications, a titration scheme for the initiation of therapy is described in Table 1, which is recommended for adults and adolescents aged 12 years and above.
Table 1. Dosing chart – initial titration
| Day 1 | Day 2 | Day 3 |
|---|---|---|
| 300 mg daily | 300 mg twice daily | 300 mg daily |
How many gabapentin 300 mg capsules are required for a prescription that will last 2 weeks (until she reviews her patient)?
QUESTION 3
Jawaid is considering prescribing amitriptyline.
If the dose was started at 25 mg daily and increased by 25 mg every 3 days to the maximum of 75 mg, how many 25 mg tablets would be required for a 2 week prescription?
QUESTION 4
Seema is treating a patient with trigeminal neuralgia and she wants to prescribe carbamazepine.
If she starts at 200 mg daily and increases the dose by 100 mg each week up to the usual dose of 200 mg four times a day, how many days will it take to reach this dose?
- 43 days
- 49 days
- 57 days