Prescribe certain medicines by brand to ensure supply of the same product. Examples are grouped by therapeutic area. The list of products is not exhaustive.

Using this list

Use this list in conjunction with these principles: Prescribing by generic or brand name in primary care

Allergy and immunology


Prescribe by brand name to ensure patients receive an auto-injector device they have been trained to use. If switching between brands, patients should receive full training in use of the new device.

Licensed doses differ between brands of adrenaline auto-injectors.

Adrenaline bioavailability may be influenced by factors including formulation and needle length.

Anaesthesia and pain

Opioid patches


Buprenorphine transdermal patches are available as 72-hourly, 96-hourly and 7-day formulations. Brand name prescribing is recommended to reduce the risk of confusion and error in dispensing and administration.


Fentanyl  transdermal patches are available as matrix and reservoir formulations. Reservoir patches must not be cut because damage to the rate-limiting membrane can lead to a rapid release of fentanyl resulting in overdose. If the prescriber intends the patch to be cut (NB: unlicensed and not recommended) then the prescription must specify a brand of matrix formulation patch.

Opioids MR

Morphine, oxycodone, tramadol

These medicines are available as 12-hourly and 24-hourly oral formulations. Brand-name prescribing is recommended to reduce the risk of confusion in dispensing and administration.



UK-licensed metolazone tablets (Xaqua) have up to two-fold difference in bioavailability compared to other (unlicensed, imported) metolazone preparations. Between 2012 and 2022, patients needing metolazone in the UK used unlicensed, imported tablets. Patients switching to the UK-licensed version may require dose adjustment depending on clinical effect; patients should be monitored for dehydration and electrolyte disturbance. For details see Metolazone preparation differences and safety considerations

Diltiazem MR

Different versions of diltiazem modified-release preparations containing more than 60mg may not have the same clinical effect.

Nifedipine MR

Different versions of nifedipine modified-release preparations may not have the same clinical effect.


Enoxaparin is a biologic medicine – biologic and biosimilar medicines should always be prescribed by brand name.



NICE guidance recommends insulins are prescribed by brand name.

It is important to ensure patients receive an administration device they have been trained to use.

Manufacturers advise any switch between brands or formulation of insulin should be done under strict supervision; a change in dose may be required.

Insulins are biologic medicines – biologic and biosimilar medicines should always be prescribed by brand name.



The BNF states there is no evidence that any one oral preparation of mesalazine is more effective than another; however, delivery characteristics of mesalazine preparations may vary.

If switching to a different brand of mesalazine, advise the patient to report any changes in symptoms.

For further information see Switching between mesalazine oral tablet preparations

Mental health


Lithium has a narrow therapeutic index and preparations vary widely in bioavailability. Changing the preparation requires the same precautions as initiation of treatment.

Methylphenidate MR

Methylphenidate modified-release (MR) preparations contain both immediate-release (IR) and MR methylphenidate. The proportion of IR and MR methylphenidate differs between brands; different preparations may not have the same clinical effect.


Antiseizure medications for seizure disorders

NICE epilepsy guidelines recommends consistent supply of the same preparation for patients with seizure disorders, unless the prescriber, in consultation with the patient and their family or carers, considers this not to be a concern.

MHRA guidance groups antiseizure medications into three categories of risk to help healthcare  professionals decide whether it is necessary to maintain continuity of a specific manufacturer’s product. These groups are:

Category 1

Specific measures are necessary to ensure consistent supply of a particular product (which could be either a branded product or specified manufacturer’s generic product) for medicines in this category.
Medicines: carbamazepine, phenobarbital, phenytoin, primidone

Category 2

By default, this category includes all antiseizure medications not listed in categories 1 or 3. The need for continued supply of a particular manufacturer’s product should be based on clinical judgement and  consultation with patient and/or carer. Consider clinical factors such as seizure frequency, treatment history and the potential implications for the individual of having a breakthrough seizure.
Medicines: clobazam, clonazepam, eslicarbazepine, lamotrigine, oxcarbazepine, perampanel, rufinamide, topiramate, valproate, zonisamide

Category 3:

Therapeutic equivalence between branded and generic products (and between generics) can be assumed for medicines in this category. They can be prescribed generically unless there are other specific reasons such as patient anxiety, confusion or risk of dosing errors.
Medicines: brivaracetam, ethosuxamide, gabapentin, lacosamide, levetiracetam, pregabalin, tiagabine, vigabatrin

Further information

Organ transplantation

Medicines to prevent transplant rejection are commissioned by NHS England and should routinely be prescribed by secondary care.


Patients should be stabilised on a particular brand of oral ciclosporin because switching between formulations without close monitoring may lead to clinically important changes in blood ciclosporin concentration.

Switching between a brand and generic formulation, or between generic formulations, should be initiated only by a transplant specialist. If switching is necessary, the patient should be monitored closely for changes in blood-ciclosporin concentration, serum creatinine, blood pressure, and transplant function.


Inadvertent switching between oral tacrolimus products has been associated with reports of toxicity and graft rejection. Oral tacrolimus products should be prescribed and dispensed by brand name only.

Switching between a brand and generic formulation, or between generic formulations, should be initiated only by a transplant specialist.



NICE CKS asthma guidelines advise generic prescribing of inhalers should be avoided as it can lead to people with asthma being given an unfamiliar device, affecting usage and adherence.

Corticosteroids: beclometasone, budesonide, fluticasone

Beclometasone dipropionate CFC-free pressurised metered-dose inhalers are not interchangeable; Qvar and Kelhale have extra-fine particules and are more potent than Clenil Modulite and Soprobec. MHRA advice to prescribe beclometasone inhalers by brand name was issued in 2008.


To ensure patients receive an inhaler they have been trained to use, tiotropium capsules and administration devices should be prescribed by brand name.

Update history

  1. Updated terminology of antiepileptics to antiseizure medications
  1. Link to SPS page on non-oral mesalazine preparations removed as page no longer exists
  1. Mycophenolate removed as brand-name prescribing is no longer considered necessary. Note added that medicines for transplant rejection should routinely be prescribed by secondary care.
  1. Direction to principles of generic/brand name prescribing moved to top of page. Metolazone: link to detailed information added. Enoxaparin added.
  1. Metolazone added following launch of UK-licensed tablets (Xaqua) that are not bioequivalent to currently used preparations
  1. Anti-epileptics consensus article attached
  1. Published

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