Even if a drug has been prescribed for many years within the European Union, there is still a need for pharmacovigilance work to develop the knowledge base around the product. During the pre-marketing phase, the drug will have been subjected to clinical trails according to EU drug safety laws. An application will have been made for a Marketing Authorisation to allow the drug to be sold within the EU. This will have been carefully considered by regulators, and the drug will only have been placed on the market should that authorisation have been duly issued. Nonetheless, the possibility for unanticipated adverse reactions is still present, even with such apparently 'well established' drugs.
Pharmaceutical Drugs Could Contain Excipients Which Invoke A Reaction
When the patient receives a prescription or over the counter drug (for example, as a tablet or capsule), it often only contains the active chemical component (the drug) as a small component of the total volume. The remaining volume consists of excipients, substances which in theory do not produce any effects. They may be present to give the tablet, capsule or other preparation its distinctive form, colour, flavour and so on. They may be added as preservatives, as dilutants, and so on. They can vary between dose strengths and formulations of the very same drug.
Pharmaceutical companies may manufacture thousands of products for which the composition and quantity of excipients used varies from product to product. The company may change suppliers for those excipients, and/or vary formulations over time. It is possible for an adverse reaction to occur with excipients, for example, lactose intolerance, or allergies or the effects of sugar in diabetic patients, etc. In previous years, there have been instances where changes to the formulation of a particular well established product have resulted in increased amounts of the active drug being absorbed by the body.
Placebos And Associations With Suspected Adverse Reactions
In the past, there have been some adverse reactions reported within clinical trials where there was an association suspected with placebos. The (EU) Clinical Trial Directive 2001/20/EC, April 4, 2001 refers to placebos within its list of 'investigational medicinal products'. Accurate and timely reporting of adverse reactions suspected to be associated with the taking of a placebo applies to clinical trials which take place during the post-marketing phase. Typically such reactions occur due to an allergy to one or more of the excipients contained within the given placebo. The same can be said for those that occur with excipients in medicinal products which contain active ingredients which may also be the cause of allergic reactions.
Problems Can Arise Even With Generic Drugs When Manufactured By Differing Pharmaceutical Companies
An important point note about generic drugs is that they will have originally been marketed as a patented formula by one particular pharmaceutical company. After sufficient time has elapsed for the patent to expire, the drug can then by made by other companies as a generic, providing the correct clinical trials are conducted according to the relevant drug safety laws prior to (and after) release onto the market. Should an adverse reaction be suspected to be associated with taking a generic formula, it is the company who made the particular generic in question who must report it to the regulatory agencies, rather than the company who held the original patent. Since there can be problems associated with excipients, cases can arise where an association is suspected with the formulation of the generic, or other aspects of its manufacturing process.
New problems can arise with 'old products'
There are numerous examples of even very serious adverse effects which have taken many years to be identified. It could have been that the rarity of the occurrence of these adverse effects meant that suspicions were not initially raised in connection with taking the particular product. Examples here include the identification of heart valve disease associated with certain types of drugs prescribed to combat obesity, or heart rhythm disturbance associated with certain non-sedating antihistamines. There have also been other instances where it has taken many years for the development of the adverse reaction, such as the development of certain types of cancer.
For the above reasons pharmacovigilance is still crucial for pharmaceutical companies, professionals, patients and the public even when a drug has been prescribed in routine practice for many years within the EU and elsewhere. It is important to note however, that the information contained here still cannot be considered as an exhaustive list of all eventualities nor as any form of formal or informal professional advice.
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