Prescribing opioids – by trade name or generic?
The registration and naming process for drugs
When new drugs come onto the market, they must be licensed by the Medicines and Healthcare Regulatory Authority (MHRA) and registered with a trade name. Details of most UK medicines and their registration is listed with their Summary of Product Characteristics on the Electronic Medicines Compendium. We are all familiar with many of these and sometimes use them as they can be shorter than the generic name.
Bringing a new drug to market incurs a huge investment so drug companies are awarded a patent on a new drug which means only they can sell it solely for up to 20 years. This enables them to recoup some of their money and fund work on new products. Once the patent expires, other manufacturers are free to make generic forms of a drug and this almost always results in price reduction. Obviously very successful drugs will be most attractive to manufacturers so there can be many versions of the same medicine available. This is certainly the case for most of the opioids we use. A quick browse of the BNF will show just how many products are available for oxycodone, for example.
The regulatory processes for generic drugs is as stringent as for new drugs so all generic versions must contain the same drug in the same dose and ostensibly be equivalent to the original. However, it may vary in its excipients – the added ingredients which make it into a dose form. In theory, all generics are the same as the original but we all know people who insist that only one brand works for them. Whilst this is unlikely from a pharmaceutical point of view, it’s not impossible and may be more than just auto-suggestion, as our unique genetics can affect how we metabolise chemicals.
When should medicines be prescribed by brand name?
Medicines can be prescribed using the brand/trade name or the generic name. If a trade name is specified, the pharmacist can only supply that one product but if the generic name is used, the prescription can be filled using the product on the shelf or the one most easily available. Prescribers are encouraged to use generic names as this offers most flexibility and can be economically beneficial to the NHS. But some medicines should always be prescribed by brand and once a patient is stabilised on a brand, they should remain on it. The categories include:
- Medicines where small differences in bioavailability between products can make a clinical difference to the efficacy of the medicine, especially if it has a narrow therapeutic window (e.g. lithium, anti-epilepsy medicines and anti-rejection drugs)
- Modified release preparations which differ in their drug release characteristics in a clinically significant way (e.g. MR diltiazem products)
- Products where a difference in formulation make products non-interchangeable (e.g. 4-day and 7-day buprenorphine patches, 12-hourly or 24-hourly MR morphine dose forms)
Advantages and disadvantages to prescribing opioids by brand name
Safety is our paramount concern for patients and ensuring they receive the right medication for them, and are instructed to take it correctly, is our responsibility. Writing prescriptions for opioids is governed by medicines law and certain details must be included before the prescription can be dispensed. However, there is no requirement to prescribe all opioids using brand names.
Immediate-release products also including liquids and injections are generally regarded as therapeutically interchangeable and it is simpler to prescribe them generically. Modified release products can be distinguished by the prescribing interval so morphine sulphate MR tablets 10mg BD indicates the prescriber’s intention clearly. Some prescribers prefer to use trade names and this is fine but if a specific product is not available on a pharmacy shelf or at the local wholesaler, there may be a delay in supply. With a generic prescription, the pharmacy has the option of ‘shopping around’ for an available product. Generic prescribing can also make administration, ordering and record-keeping simpler as controlled drugs registers on wards need not use a different page for separate brands, only for separate formulations.
Ideally, patients would get the same, familiar product each time it’s dispensed but our patients are often receiving prescriptions from more than one place and we have no control over the products they will receive. Even within an organisation, although there are hospital contracts and CCG agreements for specific brands, shortages and changes occur so substitutions are made so even if one hospice decides to stick with one product, patients will often have multiple versions of the same drug at home. We see this when people bring in their medication on admission and it is a concern when all the products have different names, appearances and packaging, as it feels all too possible for mistakes to be made and double doses to be taken.
There is no easy answer to this apart from careful review of medicines, asking patients to show you all their medicines when coming for appointments or when a home visit is made, and relying on support from all those healthcare professionals looking after the patient.