Tagged: receptors

The Acorda’s Tozadenant Phase III clinical trials

The biotech company Acorda Therapeutics Inc. yesterday announced that it was halting new recruitment for the phase III program of its drug Tozadenant (an oral adenosine A2a receptor antagonist).

In addition, participants currently enrolled in the trial will now have their blood monitoring conducted on a weekly basis. 

The initial report looks really bad (tragically five people have died), but does this tragic news mean that the drug should be disregarded?

In todays post, we will look at what adenosine A2a receptor antagonists are, how they may help with Parkinson’s, and discuss what has happened with this particular trial.


Dr Ron Cohen, CEO of Acorda. Source: EndpointNews

Founded in 1995, Acorda Therapeutics Ltd is a biotechnology company that is focused on developing therapies that restore function and improve the lives of people with neurological disorders, particularly Parkinson’s disease.

Earlier this year, they had positive results in their phase III clinical trial of Inbrija (formerly known as CVT-301 – Click here to read a previous post about this). They have subsequently filed a New Drug Application with the US Food and Drug Administration (FDA) to make this inhalable form of L-dopa available in the clinic, but the application has been delayed due to manufacturing concerns from the FDA (Click here to read more about this). These issues should be solvable – the company and the FDA are working together on these matters – and the product will hopefully be available in the new year.

So what was the news yesterday?

Acorda Therapeutics has another experimental product going through the clinical trial process for Parkinson’s disease.

It’s called Tozadenant.

Source: Focusbio

Tozadenant is an oral adenosine A2a receptor antagonist (and yes, we’ll discuss what all that means in a moment).

Yesterday Acorda Therapeutics Inc announced that they have halted new recruitment for their phase III clinical program. In addition the company is increasing the frequency of blood cell count monitoring (from monthly to weekly) for participants already enrolled in the company’s Phase 3 program of Tozadenant for Parkinson’s disease.

The Company took this action due to reports of cases of agranulocytosis.

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Dear FDA, this is bigly wrong…and you know it!

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Dopamine agonist treatments are associated with approximately 90% of hyper-sexuality and compulsive gambling cases that occur in people with Parkinson’s disease.

This issue does not affect everyone being treated with this class of drugs, but it is a problem that keeps popping up, with extremely damaging consequences for the affected people who gamble away their life’s saving or ruin their marriages/family life. 

The U.S. Food and Drug Administration (FDA) is yet to issue proper warning for this well recognised side-effect of dopamine agonists, and yet last week they gave clearance for the clinical testing of a new implantable device that will offer continuous delivery of dopamine agonist medication.

In today’s post, we will discuss what dopamine agonists are, the research regarding the impulsive behaviour associated with them, and why the healthcare regulators should acknowledge that there is a problem.


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Dopamine. Source: Wikimedia

Before we start talking about dopamine agonists, let’s start at the very beginning:

What is dopamine?

By the time a person is sitting in front of a neurologist and being told that they ‘have Parkinson’s disease’, they will have lost half the dopamine producing cells in an area of the brain called the midbrain.

Dopamine is a chemical is the brain that plays a role in many basic functions of the brain, such as motor co-ordination, reward, and memory. It works as a signalling molecule (or a neurotransmitter) – a way for brain cells to communicate with each other. Dopamine is released from brain cells that produce this chemical (not all brain cells do this), and it binds to target cells, initiating biological processes within those cells.

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Dopamine being released by one cell and binding to receptors on another. Source: Truelibido

Dopamine binds to target cells via five different receptors – that is to say, dopamine is released from one cell and can bind to one of five different receptors on the target cell (depending on which receptor is present). The receptor is analogous to a lock and dopamine is the key. When dopamine binds to a particular receptor it will allow something to happen in that cell. And this is how information from a dopamine neuron is passed or transmitted on to another cell.

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Dopamine acts like a key. Source: JourneywithParkinsons

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