Efficacy and safety of liquorice extract in asthmatic patients

Abstract

Liquorice is one of the commonly used herbs in the field of medicine due to its pharmacological activities. Among these activities, the anti-inflammatory and antiallergic activities that support its use in asthma. This study included 80 asthmatic patients who were classified into two groups, group 1(Placebo group) maintained on inhaled corticosteroids (ICs in moderate to high doses) and long-acting beta agonist (LABA) and received starch capsule (500mg starch) twice daily as placebo and group 2 (active treatment group) maintained on ICs (in moderate to high doses) and LABA and received liquorice extract capsule (500mg equivalent to 100mg glycyrrhizin) taken twice daily. The efficacy of liquorice was measured by estimation of pulmonary function and blood eosinophils %. On the other hand, safety was assessed by blood pressure measurement and determination of serum potassium level. The results revealed that addition of liquorice capsules to ICs and LABA resulted in a non-significant improvement in blood eosinophils (P-value 0.754). However, it resulted in a highly significant improvement in Forced Vital Capacity (FVC) % and Forced Expiratory Volume1 (FEV1) % when compared to group 1 (P-value 0.031.and 0.040 respectively). Regarding liquorice safety, neither Blood pressure (systolic and Diastolic) (SBP and DBP), nor serum K level showed any significant change in patients received liquorice capsules. Conclusion: liquorice in the used dose significantly improved FVC% and FEV1% but did not affect blood eosinophils. There was no significant effect on blood pressure and serum K level, so, this dose is safe with no observed side effects.