Mr Patel, a regular customer, asks if he can have a quick chat. “I’m a bit worried,” he says. “You know those capsules I get for my Raynaud’s, nifedipine I think they are called – well I saw something online yesterday that said there were stock shortages. Are you still going to be able to get them for me? I’m due to run out next month.”
What is nifedipine?
Nifedipine is a dihydropyridine calcium-channel blocker (CCB). It is a prescription-only medicine, used in the treatment of high blood pressure. It is also used in angina prophylaxis, and occasionally for the treatment of Raynaud's syndrome and chilblains (although use for the latter is unlicensed).
What are the current nifedipine stock issues?
Nifedipine was previously available as immediate-release (IR) capsules sold under the brand name Adalat, but both strengths were discontinued by March 2019. They were used for treating patients with essential hypertension or chronic stable angina pectoris if no other treatment is appropriate, but were not considered the first-line treatment for these conditions. IR capsules were also the only licensed product for the treatment of Raynaud's syndrome.
Nifedipine is still available as modified-release (MR) tablets or capsules, but some of these brands have been periodically out of stock. In June, the Specialist Pharmacy Service advised that there have been intermittent supply issues with some of the nifedipine MR products, and some manufacturers have reported to C+D that some local supply issues still remain. You should call your local suppliers for the latest stock availability.
How can you reassure Mr Patel?
Although MR nifedipine formulations are not licensed for the treatment of Raynaud’s syndrome, clinical evidence suggests that they are effective in this condition. You should reassure Mr Patel that he could be switched to a similar dose of an MR preparation (off-label) and he will not be left without any treatment options. MR preparations have also been shown to have fewer adverse reactions than IR preparations.
You should suggest that he makes an appointment with his GP as soon as possible to discuss switching his treatment.
You could also reassure Mr Patel that this switch to an MR formulation may just be temporary – as although Adalat IR was the only IR nifedipine product available, the Department of Health and Social Care has said another supplier is in the process of launching an IR preparation, which is anticipated to become available by early September 2019.
Switching between IR and MR formulations
There is no guidance or data on dose conversion between IR and MR nifedipine preparations, so if a patient needs to be switched, the nearest equivalent daily dose should be prescribed. For those patients taking nifedipine for hypertension or angina prophylaxis, blood pressure and/or frequency of angina attacks (if applicable) should be closely monitored in the initial stages of the switch. The patient should also be monitored for adverse effects, such as headaches, dizziness and oedema.
What other advice do you need to give?
You will need to counsel patients on the change in frequency of dosing when switching from IR to MR nifedipine preparations to prevent dosing errors. IR capsules are taken three times daily, while MR preparations are taken 1-2 times daily, depending on the brand.
Can you switch between MR preparations in the event of a brand shortage?
Different versions of MR preparations may not have the same clinical effect and therefore it is recommended that they are prescribed by brand to avoid confusion. In the event of a shortage, brand prescribing may not be possible, and patients should be switched to the nearest equivalent dose of another MR nifedipine formulation. Closer monitoring of blood pressure may be required in the initial stages and patients reassured that they are receiving the same drug and dose, but to report any adverse effects.
You can find further information about nifedipine and its stock shortages at:
- Specialist Pharmacy Services: Adalat (nifedipine) products: discontinuations and shortages
- British National Formulary: Nifedipine
- NHS.uk: Nifedipine.
- Specialist Pharmacy Services (June 2019) Adalat (nifedipine) products: discontinuations and shortages.
- British National Formulary (2019) Nifedipine.
- NHS.uk: Nifedipine.
- Nice Clinical Knowledge Summaries (October 2016) Raynaud's phenomenon.