Assessment of the short-term safety and tolerability of a quantified 80 % ethanol extract from the stem bark of Nauclea pobeguinii (PR 259 CT1) in healthy volunteers: a clinical phase I study.

The aim of this study was to evaluate the short-term safety and tolerability of an antimalarial herbal medicinal product (PR 259 CT1) consisting of a quantified 80 % ethanol extract from the stem bark of Nauclea pobeguinii when given orally to healthy adult male volunteers. The amount of the major alkaloid strictosamide in the extract was determined by a validated HPLC method and was shown to be 5.6 %. The herbal preparation was formulated in a gelatine capsule form containing 500 mg of PCR 259 CT1. A sample of 15 healthy male volunteers, selected using the Lot Quality Assurance of Sampling (LQAS) method, was eligible for inclusion after fulfillment of the inclusion criteria and clinical examination by a physician. The volunteers were treated in an outpatient clinic with a drug regimen of two 500 mg capsules three times daily (each eight hours) for seven days, during meals. Safety and tolerability were monitored clinically, haematologically, biochemically and by electrocardiographic (ECG) examination at days 0, 1, 3, 7 and 14. Adverse effects were recorded by self-reporting of the participants or by detection of abnormalities in clinical examinations by a physician. The oral administration of PR 259 CT1 at high doses of 2 × 500 mg/capsule/day for 7 days was found to induce no significant changes in the concentration levels of all investigated haematological, biochemical, electrocardiogram and vital sign parameters and physical characteristics after 14 days of treatment compared to those seen in the baseline data. The concentration levels of all evaluated parameters were within the normal limits as reported in the literature. All adverse events noted were mild and self-resolving including increase of appetite (33 %), headache (20 %) and nausea (20 %). Other minor side effects were insomnia, somnolence and asthenia (7 %). Thus, PR 259 CT1 presented a significant safety and tolerability in healthy volunteers to allow its further development by starting a phase II clinical trial.