About dopamine blockers & depletors
Dopamine blockers and depletors are medications that prevent the body from using or producing the neurotransmitter dopamine. These drugs may be used to treat a number of health problems, including some neurological conditions.
Dopamine is a neurotransmitter that helps regulate body movements and other motor and cognitive functions. In healthy bodies, neurons produce and release dopamine in the brain and other parts of the body. When the dopamine is released by one neuron, it is received by the receptors of the next neuron. This chain reaction eventually leads to the stimulation of nerves.
Adequate amounts of dopamine in the brain help promote smooth, coordinated movement. Over-production or increased activity of dopamine can result in movement disorders, such as the characteristic chorea of Huntington's disease and the tics of Tourette syndrome. Inadequate levels or decreased activity of dopamine triggers symptoms such as tremor, rigidity and bradykinesia (slowness of movement).
Dopamine blockers and depletors are used to treat conditions that arise from the over-production or increased activity of dopamine. Dopamine blockers work by binding to and blocking the action of dopamine receptors. This prevents the receptors from using the dopamine that is present in the brain or elsewhere in the body. Conversely, dopamine depletors work by preventing dopamine from being stored or released by neurons.
There are numerous types of dopamine blockers and depletors. Some of the most common include pimozide (Orap), haloperidol (Haldol) and olanzapine (Zyprexa). Tetrabenazine is also a common medication as it acts as both a dopamine blocker and depletor.
Other examples of dopamine blockers and depletors include:
- chlorpromazine hydrochloride (Thorazine)
- droperidol (Inapsine)
- fluphenazine hydrochloride (Prolixin)
- metoclopramide (Reglan)
- perphenazine (Trilafon)
- prochlorperazine (Compazine)
- thiethylperazine (Torecan)
- trimethobenzamide (Tigan)
- reserpine (Serpalan)
Dopamine blockers and depletors are available in different forms, such as pill or injection. Some long-acting injections may last for up to six weeks.
Dopamine blockers and depletors may be used to treat various disorders that arise from the over-production or increased activity of dopamine in the brain and elsewhere in the body. They are commonly used to treat movement disorders such as the characteristic chorea of Huntington's disease, the tics of Tourette syndrome or the repetitive, involuntary movements of tardive dyskinesia.
These medications may also be used to treat certain psychotic disorders that are related to dopamine production, such as schizophrenia, which is caused by an increase in dopamine activity. Additionally, dopamine blockers are effective at reducing nausea and vomiting in some people. They may be recommended for people who are undergoing chemotherapy or experiencing post-operative nausea. Dopamine blockers may also be used to treat autism, particularly in children.
Some non-neurological conditions, such as gastroesophageal reflux, may be treated with these drugs.
Conditions of concern
Patients are urged to tell their physician if they have been diagnosed with any medical condition. These include any allergies, especially if they have ever experienced an allergic reaction to previous use of dopamine blockers or depletors, or an allergic reaction to other substances such as foods, preservatives or dyes.
Other conditions of concern with regard to using dopamine blockers or depletors include:
- Alcohol abuse
- Heart or blood vessel disease
- High blood pressure
- Kidney or liver disease
- Lung disease
- Thyroid problems
People who have Parkinson’s disease or other form of parkinsonism should not take dopamine blockers or depletors. Parkinson’s disease is caused by low levels of dopamine in the brain and the use of dopamine blockers or depletors can significantly increase the severity of symptoms.
- Side effects
Potential side effects
Dopamine blockers and depletors can cause side effects similar to symptoms of Parkinson’s disease. These side effects include slowness of movement (bradykinesia) and mobility problems. Once people stop taking dopamine blockers and depletors, these side effects typically disappear. Long-term use of these medications may also cause tardive dyskinesia. However, dopamine depletors are less likely to cause tardive dyskinesia than dopamine blockers.
Additional side effects associated with dopamine blockers and depletors may include:
- Excitability, restlessness
- Muscle stiffness, muscle spasms
- Difficulty in speaking or swallowing
- Weakness in the arms and legs
- Dizziness, loss of balance
- Vision loss or blurred vision
- Photosensitivity (sensitivity to light), which may lead to sunburn or rash
- Less sweating, which may cause the body to overheat
- Dry mouth
- Nausea or vomiting
Drug or other interactions
Of particular concern to patients taking some dopamine blockers and depletors are the following:
- Seizure medications
- Levodopa (a dopamine precursor used to treat Parkinson’s disease)
- High-blood pressure medication
- Certain antidepressants (e.g., MAO inhibitors, tricyclic antidepressants)
- Certain antipsychotic medications
- Beta blockers
- Medications that depress the central nervous system and cause drowsiness such as alcohol and allergy medications
- How to use
Pregnancy use issues
Some dopamine blockers and depletors should not be taken by women who are pregnant or breastfeeding. Other types of these medications may be taken safely. Women are urged to consult with their physician about the potential risks and benefits of taking these medications during pregnancy or while nursing.
Child use issues
Some dopamine blockers and depletors may be safe for use by children, while the safety of others has not been established. For this reason, parents are urged to consult with a physician about the risks and benefits of allowing children to use these medications.
Elderly use issues
Dopamine blockers and depletors can safely be used by older patients. However, dosage levels may need to be adjusted, as elderly patients are often more susceptible to a medication’s side effects than are younger adults.
Symptoms of medication overdose
Patients or loved ones of patients exhibiting any of these symptoms should seek immediate medical attention:
- Breathing difficulties
- Irregular heartbeat
- High fever
- High or low blood pressure
- Extreme fatigue or weakness
Questions for your doctorPatients may wish to ask their doctor the following questions related to dopamine blockers and depletors:
- Why do you recommend I take a dopamine blocker or depletor?
- Are there alternative treatment methods that I should consider?
- What are the side effects of the drug you are recommending?
- Should I continue to take the medication if I notice side effects?
- Are there additional medications I could take that may counteract these side effects?
- Should I make certain lifestyle changes while taking dopamine blockers or depletors?
- Will these drugs interact with any medications I am currently taking?
- What should I do if I miss a dose of my medication?
- For how long will I have to take these drugs?
- What risks are involved with long-term use of these drugs?
- What should I do if my symptoms get worse?