By Paljit Mudhar, Industry Analyst, Pharmaceuticals and Biotechnology

Parkinson Disease’s (PD) is a slowly progressive disease generally associated with tremor or trembling of the arms and legs, stiffness and rigidity of the muscles and slowness of movement. The cause is still unknown, although medical experts know the problem is related to a chemical imbalance in the brain. Parkinson’s disease typically affects people over 40. A small proportion, around 5 percent develop Parkinson’s in their teens.

Frost & Sullivan estimates that the anti-Parkinsonsian drugs market was valued at $1.10 billion in 2005 and is expected to grow at a CAGR of 2.2 per cent from 2005 to 2012. By 2012 it is likely to reach a value of $1.28 billion. Levodopa is the gold standard therapy drug for Parkinson’s disease and is still considered the most efficacious. However, long term use can cause many side effects because levodopa can lose its beneficial effects over time. Levodopa/carbidopa therapy is usually highly effective for the first 2 to 5 years of treatment. Dopamine agonists are currently used as the first line of defense against Parkinson’s disease. If dopamine agonists are used in monotherapy at earlier stages of the disease, they become the first line of defence against Parkinson’s disease and reduce the requirement for high levels of levodopa early on. Dopamine agonists produce fewer long-term side effects such as 'on/off' fluctuations and dyskinesias.

Dopamine agonists work by directly stimulating the dopamine receptors to bypass the degenerating brain cells. These drugs include bromocriptine (Parlodel), lisuride, pergolide (Celance), cabergoline (Camases), ropinirole (Requip), talipexole (only available in Japan), pramipexole (Mirapexin) and apomorphine (Apo-go). The side effects of dopamine agonists are similar to levodopa although nausea and mental problems such as hallucinations usually occur more often.

Up until now, patients have mostly taken a dopamine agonist, an agent that acts directly on the dopamine receptors in the brain in tablet form, or through injections or through a pump. The main issue is that when the drug is taken orally the medication in the blood stream goes through a peak and trough cycle. Data has shown that by eliminating these peaks and troughs and supplying consistent drug levels, the brain may prevent or delay abnormal movements (dyskinesia) and decrease side effects.

Administration via a patch offers convenience of once a day dosing and ease of use. One of the largest problems based on current treatments is that Parkinson’s disease patients have to keep the right amount of medications in their systems throughout the day. Therefore the patch bypasses this issue and provides a major added value for the end user. It eliminates the peaks and troughs in drug levels associated with oral treatment that can lead to fluctuations in symptom control, by delivering a steady and continuous dose. Additionally, transdermal delivered medications bypasses the stomach and absorption is not dependent on stomach emptying times.

Neupro®, the first Parkinson’s patch available in the market by Schwarz Pharma highlights the advances in the delivery of treatments for Parkinson’s disease. In terms of rotigotine, the main features include a promising receptor profile, rapid metabolism and low potential of pharmacokinetic drug-drug interactions. The purpose of the skin application is to produce stable plasma concentrations. Neupro is a Parkinson’s disease treatment designed to be given to patients in the early stages of the disease as monotherapy, without the requirement of levodopa. Neupro’s active ingredient is rotigotine, a non-ergoline dopamine receptor-agonist which is formulated as a transdermal delivery system in the form of a patch, providing a new and innovative treatment option for early Parkinson’s disease.

So what are the benefits? Neupro, via the patch delivers a dose of rotigotine over 24 hours, so patients only having to change the patch once a day. For example, pills may need to be taken early in the morning and often several times a day. This disrupts the quality of life of an individual. The patch can be worn throughout the night. In addition, it can also help those patients that have problems swallowing pills and those with digestion problems that stop oral drugs being fully absorbed. Clinicians will also benefit from prescribing this new and simple way of delivering a dopamine agonist. Many consider the dopamine agonist patch as a useful addition to the range of Parkinson's drugs, giving clinicians and patients another treatment option to consider.

However, the main issue is that when dopamine agonists are used alone, they are less effective than levodopa at controlling symptoms and the dose often needs to be increased slowly over time. The actual purpose of delaying levodopa treatment is to delay the motor fluctuations that eventually occur with long-term levodopa therapy. Additionally, these new medications are more expensive, compared to existing dopamine agonist treatments. However, because of the increased focus on earlier treatment and managing levodopa complications, dopamine agonists will drive future growth.

What else does the future hold? Deep brain stimulation is being experimented with to treat Parkinson’s disease. In this treatment, electrodes are placed in the thalamus and a pacemaker is used to stimulate the area. Researchers have also shown that foetal tissue can survive being transplanted into adult brain cells that have died as a result of Parkinson's disease. So exciting developments exist in the longer term, however at the moment the dopamine agonist will still create the largest buzz in terms of developments within the Parkinson’s field.

This article originates from Frost and Sullivan

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