carbidopa/levodopa

Action and Spectrum

Actions and Spectrum:

Actions: 

• Carbidopa is a peripheral decarboxylase inhibitor, which helps to prevent the breakdown of levodopa before it reaches the brain.
• Levodopa is a naturally occurring amino acid that is converted into dopamine in the brain, which helps to improve motor function and relieve the symptoms of Parkinson’s disease.

Spectrum: 

• Carbidopa/levodopa is effective in treating the symptoms of Parkinson’s disease, including tremors, stiffness, bradykinesia (slowness of movement), and postural instability (difficulty maintaining balance).
• It may also be effective in treating related symptoms such as depression, anxiety, and sleep disturbances.
• Carbidopa/levodopa is not a cure for Parkinson’s disease, but it can help to improve quality of life for people with the condition by reducing symptoms and improving mobility.

Drug Interaction

Adverse Reaction

Frequency Defined

>10% 

Duopa 

Nausea (30%) 

Incision site erythema (19%) 

Constipation (22%) 

Complication of device insertion (57%) 

Dyskinesia (14%) 

Post procedural discharge (11%) 

Depression (11%) 

1-10% 

Duopa 

Hypertension (8%) 

Oropharyngeal pain (8%) 

Upper respiratory tract infection (8%) 

Atelectasis (8%) 

Peripheral edema (8%) 

Anxiety (8%) 

Confusional state (8%) 

Dizziness (8%) 

Postoperative ileus (5%) 

Hiatal hernia (8%) 

Sleep disorder (5%) 

Excessive granulation tissue (5%) 

Pyrexia (5%) 

Rash (5%) 

White blood cells urine positive (5%) 

Bacteriuria (5%) 

Hallucination (5%) 

Diarrhea (5%) 

Psychotic disorder (5%) 

Black Box Warning

Black Box Warning

The black box warning for carbidopa/levodopa, a medication used to treat Parkinson’s disease, is related to the risk of developing impulse control disorders (ICDs) such as compulsive gambling, shopping, hypersexuality, and overeating.

Contraindication / Caution

Contraindication/Caution:

Carbidopa/levodopa is a medication used to treat Parkinson’s disease. The following are the contraindications and precautions of carbidopa/levodopa: 

• Allergic reaction: Patients who have a history of hypersensitivity or allergic reaction to carbidopa, levodopa, or any other component of the medication should not take carbidopa/levodopa.
• Narrow-angle glaucoma: Patients with narrow-angle glaucoma should not take carbidopa/levodopa as it may worsen the condition.
• Melanoma: Patients with a history of melanoma should be cautious when taking carbidopa/levodopa, as it has been associated with an increased risk of developing this type of skin cancer.
• Mental health conditions: Patients with a history of mental health conditions such as depression, anxiety, or psychotic disorders should be closely monitored when taking carbidopa/levodopa, as it may worsen these conditions.
• Low blood pressure: Carbidopa/levodopa can cause low blood pressure, especially in patients who are dehydrated or have other medical conditions that affect blood pressure.
• Drowsiness: Carbidopa/levodopa may cause drowsiness, and patients should not drive or operate heavy machinery until they know how the medication affects them.
• Pregnancy and breastfeeding: Carbidopa/levodopa has not been adequately studied in pregnancy and breastfeeding and is not recommended for use during these times.

Pregnancy / Lactation

Pregnancy warnings:    

Pregnancy category:  

The AU TGA classifies pregnancy category: B3 

The US FDA classifies pregnancy category: C 

Lactation: Excreted into human milk is known 

Pregnancy Categories:      

• Category A: Studies that were well-controlled and met expectations revealed no risk to the fetus in either the first or second trimester. 
• Category B: There were lack of studies on pregnant women and no evidence of risk to the foetus in animal experiments. 
• Category C: there was evidence of risk of adverse effects in animal reproduction studies, and no adequate evidence in human studies must take care of potential risks in pregnant women. 
• Category D: adequate data available with sufficient evidence of human fetal risk from various platforms, but despite the potential risk, and used only in emergency cases for potential benefits. 
• Category X: Drugs listed in this category outweigh the risks over benefits. Hence these categories of drugs need to be avoided by pregnant women. 
• Category N: There is no data available for the drug under this category. 

Pharmacology

Pharmacology:

Carbidopa/levodopa is a combination medication used to treat Parkinson’s disease. Carbidopa is a peripheral decarboxylase inhibitor that prevents the conversion of levodopa to dopamine outside of the central nervous system. This helps to increase the amount of levodopa that reaches the brain, where it is converted to dopamine and helps to improve symptoms of Parkinson’s disease.

Pharmacodynamics:

levodopa acts as a precursor to dopamine, the neurotransmitter that is deficient in Parkinson’s disease. Carbidopa helps to prevent the breakdown of levodopa in the periphery, allowing more of the medication to reach the brain.

Pharmacokinetics:

Absorption 

carbidopa/Levodopa is absorbed into the bloodstream quickly after oral administration. The rate of absorption is increased when taken with food. 

Distribution 

The drug is distributed throughout the body and can reach the brain, where it helps to increase the levels of dopamine and improve the symptoms of Parkinson’s disease. 

Metabolism 

carbidopa helps to prevent the breakdown of levodopa in the peripheral tissues and reduces the production of unwanted side effects. Levodopa is metabolized in the liver and converted into dopamine. 

Elimination and Excretion 

The metabolites of levodopa are excreted in the urine. The elimination half-life of carbidopa/levodopa is approximately 3 hours.

Adminstartion

Administration:

Orally administration

carbidopa/levodopa is a medication used to treat the symptoms of Parkinson’s disease. It is usually taken orally, in tablet or capsule form. The administration of carbidopa/levodopa involves the following steps: 

• Determining the dosage: The dosage of Carbidopa/Levodopa is usually determined by a healthcare provider and may vary depending on the severity of symptoms and the patient’s response to the medication.
• Taking the medication: The patient should take the medication as directed by their healthcare provider, usually with or without food. They should not crush or chew the tablets or capsules, as this may affect the effectiveness of the medication.

Monitoring symptoms: The patient should monitor their symptoms and report any changes to their healthcare provider. If the medication is not effective in reducing symptoms, the dosage may need to be adjusted. 

Patient Information Leaflet

Patient information leaflet

Generic Name: carbidopa/levodopa

Why do we use carbidopa/levodopa?

carbidopa/levodopa is used to treat the symptoms of Parkinson’s disease. Parkinson’s disease is a progressive disorder that affects movement, causing symptoms such as tremors, stiffness, and difficulty with coordination and balance