Effect of Carbidopa Dose on Levodopa Pharmacokinetics With and Without Catechol-O-Methyltransferase Inhibition in Healthy Subjects.

BACKGROUND AND OBJECTIVES: The treatment of Parkinson's disease (PD) is still symptomatic since disease-modifying treatments for PD are not available. Oral levodopa is the gold standard for the treatment of PD motor symptoms. However, incomplete and fluctuating plasma exposure of levodopa leads to suboptimal treatment of the symptoms. The main objective of this study was to investigate to what extent increased carbidopa doses (50 and 100 mg) increase the plasma levels of 100-mg immediate-release (IR) levodopa compared to a 25-mg carbidopa dose with and without co-administration of 200 mg entacapone. METHODS: A double-blind, placebo-controlled, randomized, crossover, phase I, pharmacokinetic study with 25 healthy volunteers was conducted. In addition, a semi-mechanistic pharmacokinetic model was built to theoretically evaluate the effect of inhibiting aromatic amino acid decarboxylase (AADC) and catechol-O-methyltransferase (COMT) mediated metabolism of levodopa on the exposure of levodopa. RESULTS: The effect of increased carbidopa doses 50 and 100 mg on the total exposure (AUC) of 100 mg IR levodopa was +29% and +36%, respectively, when entacapone was co-administered. Without entacapone, the corresponding increases were +13% and +17%. With entacapone co-administration, the increased carbidopa dose also clearly increased levodopa trough concentration. There was no significant effect on the peak concentrations of levodopa. CONCLUSIONS: Increasing carbidopa doses significantly increased the exposure and reduced the fluctuation of IR levodopa in plasma during simultaneous COMT inhibition with entacapone. Theoretical pharmacokinetic simulations suggested that the plasma profile of oral IR levodopa can be even further improved by optimizing AADC and COMT inhibition.

Increased dose of carbidopa with levodopa and entacapone improves "off" time in a randomized trial.

OBJECTIVE: To investigate whether increased fixed carbidopa doses of 65 or 105 mg (ODM-101/65 and ODM-101/105) in combination with 75, 100, 125, or 150 mg of levodopa and 200 mg of entacapone might improve "off" time in fluctuating Parkinson disease (PD) compared to the standard combination of 4:1 levodopa/carbidopa with the usual 200 mg of entacapone (LCE) during a 4-week treatment period. METHODS: This was a randomized, double-blind, double-dummy, active-controlled, crossover, multicenter, phase II, proof-of-concept study in patients with fluctuating PD. RESULTS: One hundred seventeen patients were randomized into the study (mean age 67.0 years; daily "off" time 5.3 hours; mean daily levodopa dose 610 mg). Carryover-adjusted mean changes from baseline "off" times were during ODM-101/65, -1.53 hours (p = 0.02 vs LCE), during ODM-101/105, -1.57 hours (p = 0.01 vs LCE), and during LCE -0.91 hours. Changes in daily "on" time without dyskinesia were 1.54 hours (p = 0.005 vs LCE), 1.38 hours (p = 0.0214 vs LCE), and 0.69 hours, respectively. Changes in "on" time with troublesome dyskinesia were <0.1 hours and not significantly different between treatments. In patients with high-activity COMT genotypes Val/Met or Val/Val, "off" time was reduced more with ODM-101/65 and ODM-101/105 than with LCE (p = 0.015 and p = 0.006). No difference between the treatments was seen in safety and tolerability. The most common treatment-related adverse effects were nausea, dizziness, drug-effect decrease, and dyskinesia, which were in most cases mild or moderate in severity. Treatment-related serious adverse events were diarrhea (ODM-101/105 and LCE), and myocardial ischemia and blood creatine kinase increase (LCE). CONCLUSION: Increasing the dose of carbidopa in combination with levodopa and entacapone should be considered in the treatment of fluctuating PD to improve daily "off" times. Genotyping patients with PD according to COMT activity may improve individual treatment strategies. CLINICALTRIALSGOV IDENTIFIER: NCT01766258. CLASSIFICATION OF EVIDENCE: This study provides Class II evidence that an increased dose of carbidopa improves motor fluctuations when administered with levodopa and entacapone.

Oral Levosimendan Increases Cerebral Blood Flow Velocities in Patients with a History of Stroke or Transient Ischemic Attack: A Pilot Safety Study.

BACKGROUND: Intravenous levosimendan is indicated for acute heart failure. The compound has shown promising beneficial effects in ischemic stroke models. OBJECTIVE: We evaluated the efficacy and safety of oral levosimendan in patients with a history of cerebral ischemia. METHODS: In a randomized, double-blind, placebo-controlled, parallel-group study, 16 patients with a history of ischemic stroke/transient ischemic attack received oral levosimendan in 5 escalating doses from 0.125 to 2.0 mg daily for 18-day intervals of each dose; 5 patients received placebo. Twenty-four-hour ambulatory ECG and cerebral blood flow velocities using transcranial Doppler ultrasound were recorded at baseline and at the end of each dosing period. Vasomotor reactivity was assessed via the breath holding index. In addition, plasma levels of N-terminal-pro-B-type natriuretic peptide (NT-pro-BNP) and the metabolites of levosimendan were determined. RESULTS: Levosimendan induced an increase in cerebral blood flow velocities and a decrease in NT-pro-BNP compared with placebo. There was no significant effect on breath holding index. Doses ≥0.5 mg increased heart rate by 5 to 9 beats/min. The dose level of 2.0 mg exceeded the preset safety margin of ventricular extrasystoles per hour (ie, upper 90% CI of the ratio of levosimendan to placebo above 2) with an estimate of 3.10 (90% CI, 0.95-10.07). CONCLUSIONS: Oral levosimendan increases cerebral blood flow velocities and diminishes NT-pro-BNP levels in patients with earlier ischemic cerebrovascular event. Daily doses up to 1.0 mg were well tolerated, whereas the 2.0 mg dose level induced an increase in ventricular extrasystoles. ClinicalTrials.gov identifier: NCT00698763.

Entacapone and prostate cancer risk in patients with Parkinson's disease.

BACKGROUND: The association between Parkinson's disease (PD) and prostate cancer, both common in elderly men, is disputable. In the STRIDE-PD study, prostate cancer developed in 9 patients (3.7%) receiving levodopa/carbidopa with entacapone, a catechol-O-methyltransferase inhibitor, versus 2 cases (0.9%) without entacapone. The current pharmacoepidemiological study aimed to determine whether entacapone increases prostate cancer incidence or mortality in PD patients and whether cumulative exposure affects these rates. METHODS: We performed a retrospective cohort study using population-wide health care registers with patient-level linkage. Prostate cancer incidence and mortality were modeled by Cox's proportional hazards models. RESULTS AND CONCLUSIONS: Use of entacapone with l-dopa/dopa decarboxylase inhibitor caused no increased risk of prostate cancer incidence (hazard ratio [HR]: 1.05; 95% confidence interval: 0.76-1.44) or mortality (0.93; 0.43-1.98). The HR for cumulative entacapone use of >360 days versus never-use was 0.82 (0.56-1.18) for prostate cancer incidence and 1.27 (0.60-2.72) for prostate cancer mortality.

The effect of different dosing regimens of levodopa/carbidopa/entacapone on plasma levodopa concentrations.

BACKGROUND: Repeated dosing of levodopa/carbidopa/entacapone (LCE) has shown a favourable pharmacokinetic (PK) profile compared with levodopa/carbidopa (LC), but increases maximum plasma levodopa concentrations (C(max)) during the day. High levodopa concentrations are associated with peak-dose dyskinesias. PURPOSE: To determine whether administering LCE 75/18.5/200 and 125/31.5/200 mg (LCE 75 and LCE 125) following a morning dose of LCE 100/25/200 and 150/37.5/200 mg (LCE 100 and LCE 150), respectively, would avoid the increase in levodopa C(max) values observed during multiple dosing of LCE 100 and LCE 150. METHODS: This was an open, randomized, three-period, crossover PK trial in healthy volunteers (n = 19). Subjects were randomized to Group 1 or 2. Group 1 received in random sequence: LCE 150 followed by LCE 125 three times daily (tid); LCE 150 four times daily (qid); LC 150 qid. Group 2 received in random sequence: LCE 100 followed by LCE 75 tid; LCE 100 qid; LC 100 qid. Levodopa C(max), minimum plasma concentration (C(min)), area under the curve (AUC(0-14)) and peak-trough fluctuation (PTF) were calculated up to 14 h after the first dose. RESULTS: Levodopa C(max) was not increased when the LCE dose was decreased by 25 mg after the morning dose. In comparison to LC, levodopa C(min) levels and AUC(0-14) values for LCE were significantly higher, while the levodopa PTF was significantly smaller. CONCLUSIONS: Reducing the dose of LCE by 25 mg following the first morning dose results in a more consistent levodopa C(max) profile, avoiding levodopa accumulation while maintaining significantly higher C(min) levels and AUC(0-14) values compared with LC.

Comparison of pharmacokinetic profile of levodopa throughout the day between levodopa/carbidopa/entacapone and levodopa/carbidopa when administered four or five times daily.

OBJECTIVES: To compare plasma levodopa concentrations after repeated doses of levodopa/carbidopa/entacapone (LCE) and levodopa/carbidopa (LC). METHODS: Open-label, randomized, two-period, active-controlled, cross-over study with four dosing regimens: groups I and II (healthy volunteers and Parkinson's disease patients) received levodopa 100 mg or 150 mg four times daily, respectively, and groups III and IV (healthy volunteers) received the same strengths of levodopa five times daily. Pharmacokinetic (PK) parameters determined for levodopa included Cmin, Cmax, Cmax - Cmin, AUC, t(1/2), and tmax. RESULTS: In healthy volunteers and PD patients, mean trough levels (Cmin), Cmax, and AUC of levodopa were, in general, significantly higher during LCE compared to LC administration. Compared to Cmin, Cmax, and AUC, differences between the treatments in variability of levodopa concentrations (Cmax - Cmin) were less consistent. CONCLUSIONS: The present results on the differences in levodopa PK between LCE and LC provide a basis to evaluate the relationship of levodopa PK and the induction of motor complications in an on-going study in early Parkinson's disease using similar dosing regimens.

Entacapone prolongs the reduction of PLM by levodopa/carbidopa in restless legs syndrome.

OBJECTIVES: Levodopa is effective in the treatment of restless legs syndrome (RLS). However, due to the short duration of action of conventional levodopa/decarboxylase inhibitor formulations, multiple dosing may be required in individual patients with persisting symptoms. We assessed whether a new levodopa formulation containing levodopa, carbidopa, and entacapone (LCE) improves levodopa action in RLS. METHODS: Twenty-eight RLS patients with periodic limb movement (PLM) received single doses of Stalevo 50 (LCE50; 50/12.5/200 mg), Stalevo 100 (LCE100; 100/25/200 mg), Stalevo 150 (LCE150; 150/37.5/200 mg), Sinemet 100 (LC100; 100/25 mg), or placebo in a randomized, double-blind, crossover study with polysomnography. Periodic limb movements per hour (PLM/h) during total sleep time and PLM during total time in bed were the primary and secondary variables, respectively. RESULTS: Mean PLM/h during total sleep time after Stalevo 50 (12.6/h, P < 0.05), LCE100, LCE150, and LC100 (6.4/h, 3.5/h and 9.5/h, respectively; P < 0.01) were significantly reduced compared with placebo (25.7/h). Improvement was also observed in PLM/h during total time in bed for all treatments (P < 0.01) and a significant dose response observed between LCE doses (P < 0.05). Compared with LC100, LCE100 and LCE150 reduced PLMs during the second half (P = 0.06 and P < 0.001, respectively) or during the last 3 early morning hours (hours 5-7 from the start of recording) of the night (P < 0.05 and P < 0.01, respectively). All formulations were well tolerated. CONCLUSIONS: Single doses of LCE tablets decreased PLMs in a dose-related manner in RLS patients. Prolonged effects of levodopa on PLMs suggest that, compared with standard levodopa, this new levodopa formulation provides longer symptom control throughout the night in patients with previously untreated RLS.