Does levodopa/carbidopa, a common Parkinson's Disease drug, affect stomach emptying, blood pressure and heart rate?
Acute effects of dopaminergic therapy with levodopa/carbidopa on the gastric emptying, blood pressure and superior mesenteric artery blood flow responses to oral glucose in patients with mild to moderate Parkinson’s disease.
Professor Karen Jones, The University of Adelaide
20 participants
Sep 20, 2018
Interventional
Conditions
Summary
In this study, we are interested in looking at the acute effects of the anti-Parkinson drug, levodopa/carbidopa (Sinemet®) on the rate of stomach emptying, blood pressure and abdominal blood flow after a sugary drink, and the relationship between the rate of stomach emptying and the rise in levodopa levels. The primary hypotheses underlying the study are that (i) a therapeutic dose of levodopa (200mg) / carbidopa (50mg) will slow gastric emptying in patients with mild to moderate Parkinson’s disease and (ii) this slowing of gastric emptying will be associated with an attenuation in the fall in blood pressure, and the rise in superior mesenteric artery (SMA) blood flow, after oral glucose.
Eligibility
Inclusion Criteria3
- Patients currently taking short-acting levodopa/carbidopa
- Body Mass Index (BMI) 19 - 30 kg/m²
- A diagnosis of idiopathic PD according to the UK brain bank criteria of mild to moderate PD (Hoehn and Yahr Staging <2.5)
Exclusion Criteria18
- History of diabetes mellitus (or fasting plasma glucose >7.0 mmol/L or HbA1C > or =6.5%), severe respiratory, cardiovascular, haematologic, hepatic and/or renal disease (creatinine clearance <50 mL/min), chronic alcohol abuse or epilepsy or if iron stores, or liver function tests are two times greater than the upper limit of the following normal ranges:
- Alanine aminotransferase (ALT) < 55 U/L
- Alkaline phosphatase (ALP) 30 - 110 U/L
- Aspartate transaminase (AST) < 45 U/L
- Total bilirubin 2 - 24 µmol/L
- Haemoglobin 115 – 165 g/L (Females)
- – 180 g/L (Males)
- Ferritin 15 – 200 µg/L (Females)
- – 300 µg/L (Males)
- Medication that influence BP or GI function
- Patients taking long-acting levodopa preparations
- History of GI disease (unrelated to PD), including known gastroparesis, significant upper GI symptoms and gastric surgery
- Smoking >10 cigarettes/day
- Alcohol consumption > 20 g/day
- Blood donation in the previous 12 weeks
- Pregnancy or breastfeeding
- Inability to withdraw from the morning dose of anti-Parkinsonian medication to allow a washout.
- Contraindications to levodopa/carbidopa, including current treatment with MAO inhibitor, known hypersensitivity, narrow-angle glaucoma, melanoma and suspicious undiagnosed skin lesions.
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Interventions
Patients will attend on two separate occasions (after fasting from solids for 14 h and liquids for 12 h) at least five days apart. At t= -60 minutes, the patient will then be given either (1) an oral dose of levodopa (200mg)/carbidopa (50mg) (tablet) or (2) matching placebo. At t = -3 min, the patient will consume a drink comprising 75 g glucose labelled with 20 MBq 99mTc-calcium phytate, made up to 300ml water. The end of drink consumption will be recorded as t = 0 min Patients will then undergo concurrent measurements of gastrointestinal (GI) symptoms (questionnaire), gastric emptying (scintigraphy) , blood pressure, heart rate (Dinamap) and superior mesenteric artery blood flow (Doppler ultrasound), blood glucose , serum insulin , and plasma levodopa (L-DOPA) concentrations for a period of 3 hours i.e. t= 0-180 min, following the drink.
Locations(1)
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ACTRN12624001010583