BTS 74,398

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Bts-74398

BTS 74,398, also known as Tolcapone, is a medication primarily used in the treatment of Parkinson's disease. It functions as a COMT inhibitor, which stands for Catechol-O-Methyltransferase inhibitor, a class of drugs that help in managing the symptoms of Parkinson's disease by prolonging the effect of levodopa. Levodopa is a precursor to dopamine, a neurotransmitter that is deficient in the brains of Parkinson's patients. By inhibiting the COMT enzyme, Tolcapone reduces the breakdown of levodopa in the periphery, which results in more levodopa entering the brain and thus, an increased availability of dopamine.

Mechanism of Action

Tolcapone works by inhibiting the enzyme Catechol-O-Methyltransferase (COMT), which is involved in the breakdown of dopamine in the brain. In Parkinson's disease, the dopaminergic neurons in the brain are progressively lost, leading to a deficiency of dopamine. Levodopa is a treatment that helps to replenish dopamine levels. However, a significant portion of administered levodopa is metabolized by COMT before it can reach the brain. By inhibiting this enzyme, Tolcapone allows a greater proportion of levodopa to cross the blood-brain barrier, thereby increasing the availability of dopamine in the brain and improving the symptoms of Parkinson's disease.

Clinical Use

Tolcapone is used in conjunction with levodopa and carbidopa (a peripheral decarboxylase inhibitor) in the treatment of Parkinson's disease, particularly in patients who experience fluctuations in their response to levodopa. It is most beneficial for patients who have "wearing-off" phenomena, where the effect of levodopa wears off before the next dose can be taken, or in those who have "on-off" symptoms, characterized by unpredictable changes from mobility to immobility.

Side Effects

While Tolcapone can be effective in managing symptoms of Parkinson's disease, it is associated with several potential side effects. The most serious concern is the risk of hepatotoxicity, which can lead to liver failure. Due to this risk, its use is often restricted to patients who have not responded adequately to other treatments, and it requires regular monitoring of liver function tests. Other common side effects include diarrhea, nausea, dizziness, and insomnia.

Regulatory Status

Due to concerns about liver toxicity, the use of Tolcapone has been subject to significant regulatory scrutiny. In some countries, its use is restricted, and it is available only under specific conditions that include regular monitoring of liver function.

Conclusion

Tolcapone represents an important option in the management of Parkinson's disease, particularly for patients with fluctuating responses to levodopa therapy. However, its use requires careful consideration of the risks, particularly regarding liver health, and it is typically reserved for patients who have not adequately responded to other therapies.