Five major advantages of transdermal patches above other systems
The overwhelming majority of all drugs is available as tablets or capsules and thus has to be taken orally. For patients who have difficulty swallowing, this method of treatment can be very unpleasant. Many patients also have problems with taking medication regularly – it is easy to forget to take a tablet and then therapy success can no longer be guaranteed. A patch can replace the need to take lots of tablets, with typical treatment intervals between 24 hours and seven days. By contrast, conventional delivery systems such as tablets or capsules only provide the drug required over a very limited period of time (from a few hours up to one day at a time). Patches, however, are able to release the drug as required overnight, so that the patient’s sleep is not interrupted.
All drugs that are administered orally and then go through the gastrointestinal tract first have to pass through the liver. Depending on the drug in question, a significant amount of the medication as taken is metabolised by the liver. The remaining amount of the drug is continually reduced as a result of the body’s metabolic processes. As a result, the amount of drug actually available to the body varies greatly from a very high amount straight after taking the medication to a very low amount at the end of the application interval. By contrast, a transdermal patch ensures a constant level of the drug in question, such as pain relief medication, for example. Equilibrium is established between the amount of the substance absorbed from the patch and the amount required by the body, i.e. the body simply absorbs what it needs. The concentration of the substance in the body is always in the ideal range for the drug in question.
Many drugs not only offer the desired effects but also have lots of undesirable side effects. Substances administered orally primarily result in gastrointestinal side effects, such as nausea. Not only does the patient suffer directly as a consequence – so does his or her willingness to start or continue therapy as medically prescribed. Transdermal absorption significantly reduces most of these side effects. In addition, many substances taken orally also suffer as a result of ‘food effect’. This means that their absorption by the body is greatly influenced by whether or not food is consumed at the same time. This can result in changes to the body’s pH level. As a result, patients have to take note of whether the medication should be taken before or after meals. Since transdermal patches enable the body to absorb the substance directly, this is no longer necessary. One of the most serious side effects related to medication is liver toxicity, which means that some drugs can damage the liver. The use of LTS-TTS patches may also result in a significant reduction in side effects associated with liver damage.
A basic requirement for the oral administration of drugs is the substance’s oral bioavailability. If a substance cannot enter the bloodstream via the gastrointestinal tract, or if only a limited amount of the substance reaches the bloodstream, it is not available to take effect in the body. As a result, pharmaceutical companies have gone to great lengths to improve the bioavailability of medications. In some cases, though, these efforts are not necessary. The drug Neupro® from UCB, for example, is the first drug in the world that is only available as a transdermal patch. The active substance in Neupro®, rotigotine, has shown exceptional efficacy in the treatment of Parkinson’s disease. Since rotigotine has practically no bioavailability when taken orally, it cannot be administered as tablets or capsules. Neupro® TTS patches developed and manufactured by LTS not only offer an elegant and practical solution to treatment, it also makes it possible to use rotigotine in the treatment of Parkinson’s disease for the very first time.
Both limited oral bioavailability and metabolism of the drug by the liver after oral administration leads to the patient having to take significantly more of the substance than is actually required for therapy. When using patches, however, only the amount required enters the body. This means that for hormone replacement therapy to treat symptoms of the menopause, around 2 mg estradiol must be taken per day when administered orally. However, when administered as a patch, only 0.025 to 0.05 mg is required per day – that’s just 0.4 to 0.8% of the oral dose.