Selected physical and chemical properties of commercial Hypericum perforatum extracts relevant for formulated product quality and performance.
OBJECTIVE
The complex composition-activity relationship of botanicals such as St John's Wort (SJW) presents a major challenge to product development, manufacture, and establishment of appropriate quality and performance standards for the formulated products. As part of a larger study aimed at addressing that challenge, the goals of the present study are to (1) determine and compare the phytochemical profiles of 3 commercial SJW extracts; (2) assess the possible impact of humidity, temperature, and light on their stability; and (3) evaluate several physical properties important to the development of solid dosage forms for these extracts.


METHODS
An adapted analytical method was developed and validated to determine phytochemical profiles and assess their stability. The extract physical properties measured were particle size (Malvern Mastersizer), flow (Carr's compressibility index; minimum orifice diameter), hygroscopicity (method of Callahan et al), and low-pressure compression physics (method of Heda et al).


RESULTS
The phytochemical properties differed greatly among the extracts and were extremely sensitive to changes in storage conditions, with marked instability under conditions of elevated humidity. All extracts exhibited moderate to free-flow properties and were very hygroscopic. Compression properties varied among the extracts and differed from a common use excipient, microcrystalline cellulose.


CONCLUSIONS
Three commercial sources of SJW extracts exhibited different physical and chemical properties. Standardization to 1 or 2 marker compounds does not ensure chemical equivalence nor necessarily equivalent pharmacological activity. Flow and compression properties appear suitable for automatic capsule-filling machines, but hygroscopicity and the moisture sensitivity of the phytochemical profile are concerns.
Kopleman
S H
SH
University of Maryland, Department of Pharmaceutical Sciences, 20 North Pine Street, Baltimore, MD 21201, USA.
NguyenPho
A
A
Zito
W S
WS
Muller
F X
FX
Augsburger
L L
LL
D002626:Chemistry, Pharmaceutical; D004353:Drug Evaluation, Preclinical / Q000379:methods; D004355:Drug Stability; D006813:Humidity; D020902:Hypericum / Q000737:chemistry* / Q000378:metabolism; D008027:Light; D010777:Photochemistry / Q000379:methods; D010936:Plant Extracts / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D010946:Plants, Medicinal / Q000737:chemistry / Q000378:metabolism; D011786:Quality Control; D021281:Quantitative Structure-Activity Relationship; D012997:Solvents / Q000737:chemistry / Q000378:metabolism; D013696:Temperature
D010936:Plant Extracts; D012997:Solvents