WHO monographs on selected medicinal plants - travolekar.ru

<strong>WHO</strong> <strong>monographs</strong> on selected medicinal plants
the placebo was highly significant (–18.0 mm; 95% CI –27.2 to –8.8 mm;
p = 0.0002, ANCOVA). The results in the rheumatoid arthritis trial
showed that the mean reduction of pain reported using the visual analogue
scale was –8 mm (15%) in the group treated with willow bark compared
with –2 mm (4%) in the placebo group. The difference was not
statistically significant (estimated difference –0.8 mm; 95% CI –20.9 to
19.3 mm; p = 0.93, ANCOVA) (29).
Pharmacokinetics
The pharmacokinetics of salicin and its major metabolites were determined
in humans after oral administration of an extract of the crude drug.
The extract, corresponding to 240.0 mg salicin (1360 mg, 838 μmol), was
administered to 10 healthy volunteers in two equal doses at times 0 h and
3 h. Over a period of 24 h, levels of salicylic acid and its metabolites in
urine and serum, i.e. gentisic acid and salicyluric acid, were determined
using reverse-phase high-performance liquid chromatography. Renal excretion
rate, elimination half-life and total bioavailability of salicylates
were calculated. The results showed that salicylic acid was the major metabolite
of salicin detected in the serum (86% of total salicylates), as well
as salicyluric acid (10%) and gentisic acid (4%). Peak serum levels were
reached within less than 2 h after oral administration. Renal elimination
occurred predominantly in the form of salicyluric acid. Peak serum levels
of salicylic acid were on average 1.2 mg/l, and the observed area under the
serum concentration–time curve of salicylic acid was equivalent to that
expected from an intake of 87.0 mg acetylsalicylic acid (30).
Adverse reactions
Allergic reactions such as pruritus, urticaria, asthma and gastrointestinal
symptoms may occur (16). One case of an allergic reaction in a 32-year-old
atopic patient who showed a severe anaphylactic reaction after the ingestion
of a pollen compound containing the crude drug has been reported (31).
One case of anaphylaxis resulting from the use of an extract of the crude
drug in a patient with a history of an aspirin allergy has been reported (32).
Contraindications
Cortex Salicis is contraindicated in cases of hypersensitivity or allergy to
the plant material or to salicylates (e.g. asthma, bronchial spasm, rhinitis
or urticaria).
It is also contraindicated during pregnancy and lactation, in patients
with salicylate intolerance and patients with impaired thrombocyte function
(7, 27), and in children under the age of 12 years (7).
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