Parkinson’s disease patients, like any other patient, may take an overdose of their prescribed medicines either accidentally or intentionally. A drug dose that is high enough to cause harmful effects on the body is considered as an overdose.
Taking more than his prescribed dose of any medicine can affect each individual differently and the effect will also depend upon the type of medicine ingested as well as the quantity. Varying effects may be seen when the medicine is combined with other drugs, alcohol, or if it is taken along with food or on an empty stomach.
Causes of Drug Overdose in Parkinson’s Disease
- A Parkinson’s disease patient may be old and forgetful. A multiple drug regime may cause further confusion. Chances of repeating a dose is possible in such patients.
- Elderly patients may take the wrong medicine or incorrect and excessive dose without being aware of it.
- A patient may take double the dose to make up for a missed dose.
- Parkinson’s disease patients often suffer from depression. A large dose of medicine may be taken in an attempt to commit suicide.
Symptoms of Parkinson’s Medicine Overdose
The symptoms of overdose of any drug could be an aggravation of its normal action. The severity of symptoms is largely dependent on the amount of drug taken.
- Levodopa or a combination of levodopa/carbidopa is the most common drug prescribed to treat symptoms of Parkinson’s disease. An overdose of this drug can cause nausea, vomiting, increased heart rate, palpitations and irregular heart beats (arrhythmias). Confusion and agitation may also occur.
- Overdose with a dopamine agonist such as ropinirole may cause symptoms such as nausea, vomiting, sweating, dizziness, fainting, muscle spasms, chest pain, confusion and hallucinations. Symptoms of overdose with pramipexole, another dopamine agonist, are not known but may include any of the above.
- MAO-B inhibitors such as selegiline overdose may induce hypotension (low blood pressure) and agitation, although definite effects of overdose have not been seen with selegiline. Headache, drowsiness, dizziness, chest pain, respiratory depression and convulsions are other possible symptoms.
- Overdose with COMT inhibitors such as entacapone or tolcapone have not been reported but a large enough dosage could cause abdominal pain, diarrhea, nausea, vomiting, dizziness, respiratory depression and convulsions.
- Amantadine can result in an overdose even in fairly small amounts. It can cause hypertension (high blood pressure), arrhythmias, respiratory distress, kidney problems, insomnia, agitation, confusion, disorientation, delirium, convulsions, coma or even death.
Treatment of Parkinson’s Disease Drug Overdose
Immediate medical care is very important for successful treatment of any drug overdose.
The treatment will depend upon the medicine taken (refer to Drug Therapy in Parkinson’s Disease), amount ingested, time elapsed since then, and also to a certain extent upon the age of the patient. Some of the measures may include :
- General supportive care.
- Intravenous fluids.
- Gastric lavage or pumping of the stomach.
- Inducing vomiting.
- Activated charcoal.
- ECG to monitor the heart, especially for arrhythmias.
- Specific antidotes, if available.
- Treatment of complications.
The possibility of multiple drug involvement should be kept in mind, especially if overdosing is suspected to be intentional. Refer to the article on Other Drug Interactions with Parkinson’s Disease Medicines.
Further management will be guided by the reason for overdose – accidental or intentional.