Background: Cinnamon is considered as a treatment for many ailments in native medicine. Evidence suggests that Cinnamomum zeylanicum (CZ) has anti-microbial, anti-parasitic, anti-oxidant, blood glucose lowering properties and beneficial cardiovascular effects. The present study aims to evaluate Pharmacodynamic properties and safety of CZ in healthy adults using a Phase I Clinical Trial.

Methods: This phase I clinical trial was conducted at the Department of Pharmacology, Faculty of Medicine, University of Colombo, Sri Lanka. Thirty healthy adults were recruited for the study, conducted for a period of 3 months, with the dose of CZ (water extract) increased at monthly intervals (85 mg, 250 mg and 500 mg). Data collection was carried out at baseline and during each monthly follow up visit. Anthropometric, clinical and biochemical assessments were done at baseline and during follow up. Adverse effects and drug compliance was also evaluated.

Results: Twenty eight subjects completed the three months follow up. Mean age was 38.8 ± 10.4 years and 50% were males. There were no significant changes in the anthropometric parameters during the three months follow up. Both systolic and diastolic blood pressure reduced significant during the 1st month and this reduction was sustained throughout follow up. Full blood count, renal function tests, liver function tests, fasting blood glucose, HDL-c, VLDL-d and triglycerides remained within the normal range without any significant alteration during the 3 months. A significant reduction in the TC (p < 0.05) and LDL-c (p < 0.001) was noted at the end of the 3 months follow up period. There were no serious adverse effects (including hypersensitivity) noted. In two participants dyspepsia necessitated the discontinuation of study participation. Drug compliance was between 85 and 95% during the study period.

Conclusions: This is the first phase I clinical trial in health adults evaluating efficacy and safety of CZ. Our results demonstrate no significant side effects and toxicity of CZ, including hepatotoxicity and anti-coagulation properties. CZ demonstrated beneficial anti-hyperlipidaemic and blood pressure lowering effects among healthy adults. Further studies with larger samples and longer durations may be able to elucidate other side effects and better describe the pharmacodynamic properties.

Trial registration: SLCTR/2013/001 (Sri Lanka Clinical Trials Registry: http://www.slctr.lk/trials/106 ) (Date of Registration: 01/01/2013).