Efficacy of oral administration of licorice as an adjunct therapy on improving the symptoms of patients with Parkinson's disease, A randomized double blinded clinical trial

ETHNOPHARMACOLOGICAL RELEVANCE

Licorice preparations are used as neuroprotective remedies in Persian ethnomedicine, in order to prevent from disabilities in neurodegenerative conditions like Parkinson's disease (PD).

AIM OF THE STUDY

This study was designed to determine the licorice (root of Glycyrrhiza glabra L.) effectiveness as an adjunct treatment in the PD management.

MATERIAL AND METHODS

In this double-blinded trial, 128 patients were assessed for eligibility criteria. Seventy-eight patients were ineligible and 11 of them refused from participating. Thirty-nine PD patients (YAHR staging ≤ 3) were divided into two groups by random. The patients received oral licorice or placebo syrups with a dose of 5 cc, twice a day for 6 months. High-performance liquid chromatography and spectrophotometric instruments determined licorice syrup constituents. The patients' situation for Unified Parkinson's rating scale (UPDRS) was assessed every 6 weeks for the duration of six months. In addition, patients' blood pressure, blood glucose, sodium and potassium levels, quality of life and dizziness were determined.

RESULTS

Six weeks after intervention, total UPDRS, daily activities and tremor were significantly improved with a considerable effect size. A significant better motor test and rigidity scores were observed 4 months after licorice intake (p > 0.05). No electrolyte abnormality, significant changes in blood pressure or blood glucose levels were observed during the study. Each 5cc of syrup contained 136 mg of licorice extract with 12.14 mg glycyrrhizic acid, and also 136 μg of polyphenols.

CONCLUSION

The licorice intake could improve the symptoms in PD patients without serious adverse events.

Effect of clorazepate in spasticity and rigidity: a quantitative study of reflexes and plasma concentrations

The effect on increased myotatic reflexes of desmethyldiazepam, formed from its precursor clorazepate, was assessed in a double-blind cross-over study of 27 days duration. Eight patients with spasticity or rigidity were given placebo or active substance; first in loading doses for 2 days, then 5 mg every 12 h for a total of 10 days. A wash-out period of 7 days was interposed between the 2 10-day periods. Desmethyldiazepam had a normalizing effect on the increased phasic ankle reflexes seen in spasticity, but not on the increased tonic reflex seen in rigidity. The mean concentration of desmethyldiazepam in the steady state was 1227 nmol/l (range 600-1990 nmol/l). The plasma concentration of desmethyldiazepam tended to correlate with the percent decrease in phasic reflex activity (P = 0.08, 2-tailed). A slight drowsiness in 2 patients was the only side-effect seen. In conclusion, desmethyldiazepam given as clorazepate seems to be a suitable medicament in the treatment of spasticity.