HERBAL
MEDICINAL
PLANT
 |
COMFREY
Symphytum officinale L. (Boraginaceae)
+
BY
RETTODWIKART THENU
COMFREY
(kuhm’free)
Symphytum
officinale L. (Boraginaceae) +
SUMMARY AND PHARMACEUTICAL COMMENT
Comfrey is characterised
by its pyrrolizidine alkaloid constituents. The hepatotoxicity of these
compounds is well known, and cases of human poisoning involving comfrey have
been documented. Human hepatotoxicity with pyrrolizidine-containing plants is
well documented, particularly following the ingestion of Crotalaria, Heliotropium and Senecio species. Comfrey has traditionally been used topically for
treating wounds. Percutaneous absorption of pyrrolizidine alkaloids present in
comfrey is reported to be low, although application of comfrey preparations to
the broken skin should be avoided.
Licensed herbal products
intended for internal use are not permitted to contain comfrey. The inclusion
of comfrey in products intended for topical application is permitted, provided
the preparation is only applied to the unbroken skin and that its use is
restricted to ten days or less at any one time. As a result of a 1993 report by
the Committee on Toxicity of Chemicals in Food to the Food Advisory Committee
and the Ministry of Agriculture, Fisheries and Food (UK), the health food trade
voluntarily withdrew all products, such as tablets and capsules, and advice was
issued that the root and leaves should be labelled with warnings against
ingestion. It was considered that comfrey teas contained relatively low concentrations
of pyrrolizidine alkaloids and did not need any warning labels.
TRADE NAMES
Comfrey
(available from numerous manufacturers)
OTHER COMMON NAMES
Wallwortss Ear, Black
Root, Blackwort, Boneset,
Bruisewort,
Consound, Gum Plant, Healing Herb, Knitback,
Knitbone,
Salsify, Slippery Root, Wallwort, Consolida, Boneset
DESCRIPTION
MEDICINAL PARTS: The medicinal
parts are the fresh root and the leaves.
FLOWER AND FRUIT:
The
flowers are dull purple or violet. They are arranged in crowded, apical,
2-fayed hanging cymes. The calyx is fused and has 5 tips. The corolla is also
fused and is cylindrical-campanulate with a pentangular tube and 5- tipped
border. The tips are revolute and there are 5 awlshaped scales in the mouth of
the tube. The scales close together in a clavate form and have a glandular
tipped margin. There are 5 stamens and 1 style. The ovary is 4- valved. The
fruit consists of 4 smooth, glossy nutlets.
LEAVES, STEM AND
ROOT: The
plant grows from 30 to 120 cm in height. The root is fusiform, branched, black
on the outside and white on the inside. The stem is erect and stiffhaired. The
leaves are wrinkly and roughly pubescent; the lower ones and the basal ones are
ovate-lanceolate and pulled together in the petiole; the upper ones are
lanceolate and broad.
CHARACTERISTICS: The root is slimy
and horn-like when dried.
HABITAT: The plant is indigenous
to Europe and temperate Asia and is naturalized in the U.S.
PRODUCTION: Comfrey herb
consists of the fresh or dried above-ground parts of Symphytum officinale.
Comfrey leaf consists of the fresh or dried leaf of Symphytum officinale. Comfrey
root consists of the fresh or dried root section of Symphytum officinale.
SPECIES (FAMILY)
Symphytum
officinale L. (Boraginaceae)
SYNONYM(S)
Symphytum Radix
Related species include Prickly Comfrey (Symphytum asperum), Quaker
and Russian Comfrey (Symphytum uplandicum,
hybrid of S. officinale x S. asperum)
ORIGIN
Comfrey is a perennial found in
the United States, Australia, and parts of Asia. It is cultivated in Japan.
PHARMACOPODIAL AND OTHER MONOGRAPHS
BHC 1992(G6)
BHP 1996(G9)
Complete German Commission E(G3)
Martindale 35th edition(G85)
LEGAL CATEGORY (LICENSED PRODUCTS)
GSL (external use
only)(G37)
CONSTITUENTS
The
following is compiled from several sources, including General References G2 and
G6.
Alkaloids
Pyrrolizidine-type. 0.3%. Symphytine, symlandine, echimidine, intermidine,
lycopsamine, myoscorpine, acetyllycopsamine, acetylintermidine, lasiocarpine,
heliosupine, viridiflorine and echiumine.(1–5)
Carbohydrates
Gum (arabinose, glucuronic acid, mannose, rhamnose, xylose); mucilage (glucose,
fructose).
Tannins
Pyrocatechol-type. 2.4%.
Triterpenes
Sitosterol and stigmasterol (phytosterols), steroidal saponins and
isobauerenol.
Other Constituents Allantoin 0.75–2.55%,
caffeic acid, carotene 0.63%, chlorogenic acid, choline, lithospermic acid,
rosmarinic acid and silicic acid.
CHEMICAL COMPONENTS
COMPOUNDS
Allantoin
Mucilages (Fructans)
Triterpene
saponins: including
symphytoxide A
Tannins
Silicic acid: to some extent
water-soluble
Pyrrolizidine
alkaloids (0.03% in the leaves): including echinatine, lycopsamine, 7-acetyl
lycoposamine, echimidine, lasiocarpine, symphytine, intermedine, symveridine.
USES
USES
Comfrey is used topically to promote wound healing and
to decrease infl ammation caused by bruises and sprains. It has also been used
internally for many years as a treatment for colitis and peptic ulcer disease.
However, because hepatotoxicity may occur, internal use is no longer
recommended.
FOOD USE
Comfrey
is occasionally used as an ingredient of soups and salads. It is listed by the
Council of Europe as natural source of food flavouring (category N4). This category
indicates that although comfrey is permitted for use as a food flavouring,
insufficient data are available to assess toxicity.(G16)
HERBAL USE
Comfrey
is stated to possess vulnerary, cell-proliferant, astringent, antihaemorrhagic
and demulcent properties. It has been used for colitis, gastric and duodenal
ulcers, haematemesis, and has been applied topically for ulcers, wounds and
fractures.(G2, G6, G7, G8, G49, G64)
Figure 1. Comfrey (Symphytum officinale).
Figure 2. Comfrey – dried drug substance (leaf).
ACTIONS
In the past, comfrey was used internally to treat many conditions,
including gastrointestinal complaints. However, because its pyrrolizidine
alkaloids can cause hepatotoxicity, comfrey is now recommended for topical use
only. Comfrey should be applied once the wound has begun to heal; the allantoin
stimulates cell division and wound healing. Several studies have focused on the
toxic results of the internal use of comfrey (Couet et al, 1996; Mei et al,
2005). Studies have found comfrey to be carcinogenic. Plantain (Plantago
major) can be used in place of comfrey, both internally for its healing properties
and topically on open wounds.
PHARMACOLOGICAL ACTIONS
The
classical pharmacology of pyrrolizidine alkaloids is overshadowed by the
well-recognised toxicity of this class of compounds. Consequently, the majority
of data documented for comfrey involve toxicity. Many useful reviews have been
published on the toxicity of pyrrolizidine alkaloids in humans (see below).(5–11)
IN VITRO AND ANIMAL STUDIES
Wound-healing
and analgesic activities have been documented in rats administered comfrey
extract orally.(12) Percutaneous absorption of pyrrolizidine alkaloids obtained
from comfrey is reported to be low in rats, with minimal conversion of the
pyrrolizidine alkaloid N-oxides to the free pyrrolizidine alkaloids in the urine
(reduction of the N-oxides is required before they can be metabolised into the
reactive pyrrolic esters).(13, 14)
Rosmarinic
acid has been isolated from comfrey (S.
officinale) as the main constituent with in vitro anti-inflammatory activity.(15)
Biological activity was determined by inhibition of malonic dialdehyde formation
in human platelets. Minor components, chlorogenic and caffeic acids, were not
found to exhibit any significant activity. The pyrrolic esters have been reported
to possess mild antimuscarinic activity, which is more pronounced in the
non-hepatotoxic esters of saturated amino alcohols.(16) Conversely, the free
amino alcohols are reported to exert indirect cholinomimetic action involving
the release of acetylcholine from postganglionic sites in the guinea-pig
ileum.(16)
Comfrey
has been reported to stimulate the activity of the hepatic drug-metabolising
enzyme aminopyrine N demethylase in rats.(17)
A
comfrey extract has been reported to enhance uterine tone in vitro.(18) The
action of comfrey was reported to be weaker than that exhibited by German
chamomile, calendula and plantain, but stronger than that shown by shepherd's
purse, St. John's wort and uva-ursi.
CLINICAL STUDIES
There
is a lack of clinical research assessing the effects of comfrey and rigorous
randomised controlled clinical trials are required. The antimuscarinic
properties of certain pyrrolic esters have been utilised. Two non-hepatotoxic
pyrrolizidine alkaloids, sarracine and platyphylline, have been used for the
treatment of gastrointestinal hypermotility and peptic ulceration.(16)
The
anti-inflammatory effects of Comfrey were studied in musculoskeletal disorders.
Forty-one patients with musculoskeletal rheumatism were treated with either a
pyrrolizidine alkaloid-free ointment or placebo for 4 weeks. The patient illnesses
consisted of epicondylitis, tendovaginitis, and periarthritis.
Efficacy was
determined by evaluation of different pain parameters (tenderness on pressure,
pain at rest, pain on exercise). There was significant improvement with the ointment
compared to placebo at weeks 1, 2. and 4 in patients with epicondylitis. There
was improvement with M. tendovaginitis at week 1 and 2, but not at week
4 with the ointment compared to placebo. There was no improvement in the
peri-arthritis patients in either of the two treatment groups (Petersen, 1993).
ACTIVITIES
Alterative
(f; CRC); Analgesic (1; CAN); Antiaging (f; CRC); Antihemorrhagic (f; CAN);
Antiinflammatory (2; APA; KOM; PH2; WAM); Antileukocyte (1; PH2); Antimitotic (1;
PHR; PIP); Antimutagenic (1; PNC); Antipsoriatic (1; PNC); Antitumor (1; FAD); Astringent
(1; APA; FAD; FEL; PNC); Callus-Promoter (1; PHR); Carcinogenic (1; APA; CRC); Demulcent
(1; CAN; FEL; PH2; WAM); Emollient (1; CRC; WAM); Expectorant (f; CRC; MAD); Hemostat
(f; CRC); Hepatotoxic (1; APA); Hypotensive (1; PH2); Tonic (f; FAD); Uterotonic
(1; CAN); Vulnerary (1; APA; CAN; WAM).
INDICATIONS
Adenopathy
(f; CRC); Amenorrhea (f; CRC); Anemia (f; FEL); Angina (f; PHR); Arthrosis (1;
CRC; PNC; PH2); Asthma (f; CRC); Backache (f; CRC); Bleeding (1; APA; CAN; CRC;
MAD); Bronchosis (1; APA; CRC; FAD); Bruise (2; APA; FAD; KOM; PH2; SHT); Bug
Bite (1; APA); Cancer (1; CRC; FAD; FNF; PNC); Cancer, bone (f; CRC); Cancer, lung
(1; CRC; FNF); Candida (f; CRC); Catarrh (f; MAD); Chafing (1; APA);
Cholecystosis (f; CRC); Colitis (1; APA; CAN); Congestion (f; APA); Constipation
(f; DEM); Contusion (f; PIP); Cough (f; CRC; FAD); Debility (f; FEL); Decubitis
(1; APA; JAD); Dermatosis (1; APA; FAD); Diabetes (f; MAD); Diarrhea (f; FAD;
MAD; PH2); Duodenal Ulcer (2; CAN); Dysentery (f; CRC; DEM; FAD); Dysmenorrhea
(f; CRC; MAD); Dyspepsia (f; APA); Eczema (1; PNC); Enterosis (1; CRC; PHR;
PH2); Epicondylosis (1; PH2); Fracture (1; APA; CAN; WAM); Gallstone (f; CRC);
Gastrosis (1; CRC; PHR; PH2); Gastric Ulcer (f; CAN); Gingivosis (1; APA; PHR;
PH2); Gonorrhea (f; DEM; MAD); Gout (f; CRC); Heartburn (f; DEM); Hematemesis
(f; CAN; FAD); Hematochezia (f; CRC); Hemoptysis (f; MAD); Hemorrhoid (f; MAD);
Hepatosis (f; CRC); Hernia (f; CRC); High Blood Pressure (1; PH2); Hoarseness
(f; CRC); Hysteria (f; FAD); Indolent Ulcer (2; JAD); Inflammation (2; APA;
CAN; KOM; PH2; WAM); Itch (f; APA); Leukorrhea (f; CRC; MAD); Mastosis (1; FAD;
FEL); Metrorrhagia (f; FEL); Myosis (1; WAM); Nephrosis (f; CRC; MAD);
Ophthalmia (f; CRC); Osteosis (f; PH2); Pain (1; CAN); Pertussis (f; CRC); Pharyngosis
(1; PHR; PH2); Phthisis (f; MAD); Pleurosis (f; PHR; PH2); Psoriasis (1; APA;
PNC); Pulmonosis (f; CRC); Rash (1; APA); Respirosis (f; MAD); Rheumatism (1; CRC;
PH2; PNC); Scrofula (f; CRC; FEL); Sore Throat (f; CRC; PH2); Sprain (2; CRC;
KOM; PH2; SHT); Stomatosis (f; CRC); Strain (1; APA; SHT); Sunburn (f; APA);
Swelling (f; MAD); Tendovaginosis (1; PH2); Tonsilosis (f; CRC); Tuberculosis (f;
MAD); Tumor (1; FAD); Ulcer (f; CRC; MAD); Ulcus cruris (1; FNF; MAD);Vaginosis
(f; CRC; PH2); Varicosis (f; PED); VD (f; DEM); Wound (1; APA; CAN; MAD); Yeast
(f; CRC).
INDICATIONS AND USAGE
Approved by
Commission E:
• Blunt injuries
Externally, Comfrey is used for
bruises, sprains and promotion of bone healing.
UNPROVEN
USES:
The
root has been used externally as a mouthwash and gargle for gum disease,
pharyngitis, and strep throat. Internally, the root has been used for gastritis
and gastrointestinal ulcers. In Folk medicine, the root of the plant has been
used for rheumatism, pleuritis, and as an antidiarrheal agent.
PRODUCT AVAILABILITY
Capsules, extract, ointment,
tea
PLANT PARTS USED: Leaves, Roots Leaf, Rhizome
DOSAGES
DOSAGES
NOTE:
Because of the potential for hepatotoxicity, internal use of comfrey is no
longer recommended.
Wound Healing
·
Adult topical products: may be
applied to wounds as needed (5%-20% dried herb present in product); use no
longer than 6 weeks (Blumenthal, 1998)
·
Adult poultice of fresh green
leaves: may be applied prn to granulate wounds over broken bones
DOSAGES
Dosages
for oral (unless otherwise stated) administration (adults) for traditional uses
recommended in standard herbal reference texts are given below. Note: internal
use is no longer advised.
·
Dried Root/Rhizome 2–4 g as a decoction three
times daily.(G7)
·
Root, Liquid Extract 2–4mL (1 : 1 in 25% alcohol) three times daily.(G7)
·
Ointment Symphytum Root 10–15% root extractive in usual type ointment basis applied
topically three times daily.(G7)
·
Dried Leaf 2–8 g or by infusion three times
daily.(G7)
·
Leaf, Liquid Extract 2–8mL (1 : 1 in 25% alcohol) three times daily.(G7)
DOSAGES
·
Do not use (APA); do not use
root (JAD); 2–4 g root as tea 3 ×/day (CAN); 2 tsp (= ~7.4 g) root in hot tea (MAD);
·
2–4 ml liquid root extract
(PNC); 2–4 ml liquid extract (1:1 in 25% ethanol) 3 ×/day (CAN);
·
2–8 ml liquid leaf extract (1:1
in 25% alcohol) 3 ×/day (CAN); 2–8 g leaf in tea 3
×/day (CAN);
·
0.25–0.5 cup fresh leaf (PED);
6–12 g dry leaf (PED); 9 g dry leaf:45 ml alcohol/45 ml water (PED);
·
1–3 cups tea/day (5–10 g herb)
remembering PAs (PH2).
DOSAGES
Mode of Administration: The crushed
root, extracts, and pressed juice of the fresh plant are used as semi-solid preparations
and poultices for external use. The drug is a component of standardized
preparations of analgesics, antirheumatic agents, antiphlogistics,
antitussives, and expectorants.
How Supplied:
Cream—1.25 oz„ 2
oz.
Preparation: To make an infusion,
pour boiling water over 5 to 10 gm comminuted or powdered drug, steep 10 to 15 minutes,
then strain (1 teaspoonful = 4 gm drug). For external application, a decoction
of 1:10 is used, or the fresh roots are mashed.
Daily Dosage:
External Use
— The daily dosage should not exceed 1 meg of pyrrolizidine alkaloids for external
preparations calculated with 5 to 7% drug, maximum 1 ppm/gm for commercial pharmaceutical
preparations. The drug should be used for a maximum of 4 weeks.
Tea — When using the infusion, take 1 cup 2
to 3 times daily, but not for a long duration (SEE PRECAUTIONS).
PRECAUTIONS AND ADVERSE REACTIONS
Hepatotoxicity: Internal administration
of the drug, due to the presence of pyrrolizidine alkaloids, has resulted in hepatocyte
membrane injury with hemorrhagic necrosis and loss of microvilli (Yeong, 1993).
Hepatic veno-occlusive disease and severe portal hypertension has been
associated with Comfrey ingestion, and in one case report, death resulted by
liver failure (Ridker, 1989; Yeong, 1990).
Carcinogenic/Mutagenic Effects: Mutagenic
effects are associated with aqueous extracts of the alkaloid fractions (Furmanowa,
1983). Hepatocelluar adenomas have been reported in animal models receiving
diets containing Comfrey roots and leaves (Hirono, 1978). Comfrey also has chromosome-damaging
effects in human lymphocytes (Behninger, 1989).
Gastrointestinal/Kidney/Pancreas Effects: Comfrey, through
the pyrrolizidine alkaloids, has been shown to produce lesions in the
gastrointestinal tract, pancreas, and renal glomeruli in animal models
(Winship, 1991).
Respiratory Effects: Pulmonary
endothelial hyperplasia from the pyrrolizidine alkaloids has been seen in
animal models (Miskely, 1992).
Use in Pregnancy: The drug is
contraindicated during pregnancy.
Use in Nursing Mothers: Use of the drug
while nursing is contraindicated.
CONTRAINDICATIONS, INTERACTIONS, AND SIDE EFFECTS
CLASS 2A,
2B, 2C, 2D. Longterm use discouraged
(AHP). Commission E reports the herb, leaf, and root permitted for external use
only. Skin should be intact and pregnant users should first consult physician. External
dosage of pyrrolizidine alkaloids (PAs) maximum 100 g/day for a maximum 4–6 weeks/year
(AEH). Comfrey root may cause liver damage if taken internally (WAM). Contains PAs.
Internal use may cause severe hepatic damage. PAs are toxic to humans, with
liver damage with cirrhosis and ascites, or seneciosis, or veno-occlusive disease
(VOD) reported in almost all cases of severe or fatal intoxications, from
intakes of 0.5 mg/kg to 3.3 mg/kg (AEH1). Chronic comfrey use implicated in at
least one instance of hepatic VOD (PNC). Effective July 1996, the AHP Board of
Trustees recommends that all products with botanical ingredient(s) that contain
toxic PAs, including Borago officinalis, display the following cautionary statement on the
label, “For external use only. Do not apply to broken or abraded skin. Do not
use when nursing” (AHP). CAN cautions the PAs are genotoxic, carcinogenic, and
hepatotoxic. Because of the PAs, its use in pregnancy and lactation is to be avoided.
Animal studies document placental transfer and secretion into breast milk of
unsaturated PAs (CAN). May speed up metabolism of other drugs (stimulates
metabolism of aminopyrine-N-demethylase, a drug metabolizing enzyme) (CAN).
Internal use for more than 4–6 weeks is discouraged (SHT). Canadians do not
allow in food (Blackburn, 1993). “No human being or animal should eat, drink,
or take comfrey in any form” (Br. Med. J. 6163: 596;
1979). According to studies reported in the Lawrence Review of Natural Products, rats fed comfrey roots or leaves for 600 days
developed hepatocellular adenomas, with signs of liver toxicity developing
within 180 days. Urinary bladder tumors developed also, even in those on the
lowest levels of comfrey. The incidence of liver tumors was higher with dietary
roots than with dietary comfrey leaves. Alkaloids of Russian comfrey caused
chronic liver damage and pancreatic islet cell tumors after 2 years
administration in animal models (LRNP, October 1990).
CONTRA-INDICATIONS, WARNINGS
In view of the hepatotoxic properties documented for the pyrrolizidine
alkaloid constituents, comfrey should not be taken internally. The topical
application of comfrey-containing preparations to broken skin should be
avoided.
Drug Interactions None
documented. However, the potential for preparations of comfrey to interact with
other medicines administered concurrently, particularly those with similar or opposing
effects, should be considered.
Pregnancy and Lactation The safety of comfrey has not
been established. In view of the toxicity associated with the alkaloid constituents,
comfrey should not be taken during pregnancy or lactation.
CONTRAINDICATIONS
Class 2a/2b/2c herb; class 3 herb (leaf, root).
Until more research is available, comfrey should not be
used during pregnancy and breastfeeding. It should not be given to children.
Comfrey should not be used by persons who are hypersensitive to this herb. Comfrey
is for external use only, and should not be used for more than 6 weeks in 1
year. Internal use may cause fatal hepatotoxicity. Do not use this herb on broken
skin. Pyrrolizidine alkaloid content should not exceed 10 mcg.
SIDE EFFECTS/ADVERSE REACTIONS
GI: Nausea,
vomiting, anorexia, abdominal pain, hepatomegaly, hepatotoxicity, venoocculsive
disease, hepatic adenoma (all reactions from oral use)
GU: Bladder
tumors
INTEG: Hypersensitivity
reactions (oral and topical use)
INTERACTIONS
Herb
Eucalyptus: Eucalyptus
may increase the toxicity of comfrey; avoid concurrent use (theoretical)
(Jellin et al, 2008).
INTERACTIONS—CONT’D
Pyrrolizide
alkaloid (UPA)-containing herbs (agrimony, borage, coltsfoot, dusty
miller, gravel root, petasities, ragwort): Use of these herbs
with comfrey (internally) will lead to increased toxicity; do not use concurrently (Jellin et al, 2008).
Lab Test
ALT, AST, total
bilirubin: Comfrey may increase ALT, AST,
total bilirubin, and urine bilirubin.
EFFECTS
Anti-Inflammatory Effect—Comfrey
suppresses leukocyte infiltration during the inflammation process (Shipochliev,
1981).
Demultant Effect—The mucilages
act as demultants for a soothing and irritation reduction effect.
Hypotensive Effect—Symphytoxide A,
a triterpene saponin, exhibited hypotensive activity in anesthetized rats
(Ahmad, 1993).
Tissue/Nerve Stimulation—Allantoin, a
component in Comfrey, stimulates tissue repair and wound healing through cell proliferation
(Rieth, 1968). Allantoin has also had significant effect on cellular
multiplication in degenerating and regenerating peripheral nerves (Loots,
1979).
SIDE-EFFECTS, TOXICITY
Two reports of human hepatotoxicity associated with the ingestion
of comfrey have been documented.(19, 20) One case involved a 13-year-old boy who
had been given a comfrey root preparation in conjunction with acupuncture to
treat Crohn's disease. (19) The boy was diagnosed with veno-occlusive disease
of the liver and the authors concluded comfrey to be the only possible causal
factor of the liver disease. The second case involved a 49-year-old woman
diagnosed with veno-occlusive disease.(20) She had been taking various food
supplements including a herbal tea and comfrey-pepsin pills. Pyrrolizidine alkaloids
were identified in both the tea (stated to contain ginseng) and the
comfrey-pepsin pills. The authors estimated that over a period of six months the
woman had ingested 85 mg of pyrrolizidine alkaloids, equivalent to 15 mg/kg
body weight per day. This report highlighted the potential toxicity associated
with chronic ingestion of relatively small amounts of pyrrolizidine alkaloids.
The toxicity of pyrrolizidine alkaloids is well recognised. Pyrrolizidine
alkaloids with an unsaturated pyrrolizidine nucleus are metabolised in the
liver to toxic pyrrole metabolites.(8) Acute toxicity results in hepatic necrosis,
whereas chronic toxicity typically results in veno-occlusive disease
characterised by the presence of greatly enlarged liver cells.(8, 10)
Reports of human hepatotoxicity associated with pyrrolizidine alkaloid
ingestion have been documented.(5, 8–10, 21–30) Many of these reports have
resulted from crop (and subsequently flour and bread) contamination with
Crotalaria, Heliotropium and Senecio species and from the use of pyrrolizidine-containing
plants in medicinal 'bush' teas. In addition, pyrrolizidine alkaloid poisoning has
been associated with the use of herbal teas in Europe and the United
States.(20, 25–27) The diagnosis of veno-occlusive disease in a newborn infant
who subsequently died highlights the susceptibility of the fetus to
pyrrolizidine alkaloid toxicity.(30) In this case, the mother had consumed a
herbal tea as an expectorant during pregnancy. The tea, which was purchased
from a pharmacy in Switzerland, was analysed and found to contain pyrrolizidine
alkaloids. The mother did not exhibit any signs of hepatotoxicity. Interestingly,
liver function tests in 29 chronic comfrey users have been reported to show no
abnormalities.(31)
The hepatotoxicity of pyrrolizidine alkaloids is well documented
in animals.(5) In addition, carcinogenicity has been described in rats fed a
diet supplemented with comfrey.(32) The mutagenicity of comfrey has been
attributed to lasiocarpine,(23) which is known to be mutagenic and carcinogenic.
However, other workers have reported a lack of mutagenic activity for comfrey
following assessment using direct bacterial test systems (Ames), host mediated
assay (Legator), liver microsomal assay and the micronucleus technique.(33, 34)
CLIENT CONSIDERATIONS
ASSESS
·
If the client is taking comfrey
internally, which is no longer recommended, assess for hepatotoxicity: increased
hepatic function tests (AST, ALT, bilirubin), jaundice, clay-colored stools. If
these symptoms are present, use of the herb should be discontinued.
·
If the client is using comfrey
topically to promote wound healing, assess the wound for temperature, redness,
swelling, bleeding, and purulent drainage.
ADMINISTER
·
Instruct the client to store
comfrey products in a cool, dry place, away from heat and moisture.
·
Instruct the client not to use
comfrey for more than 6 weeks in 1 year.
TEACH CLIENT/FAMILY
§ Caution the client not to use comfrey in children or
those who are pregnant or breastfeeding until more research is available.
§ Because hepatotoxicity may occur, caution the client not
to take comfrey internally. In some countries internal use has been banned.
§ Advise the client not to use comfrey on broken skin.
Absorption of pyrrolizidine alkaloids may occur.
PREPARATIONS
PROPRIETARY
SINGLE-INGREDIENT PREPARATIONS
Austria: Traumaplant. Czech Republic: Traumaplant. Germany: Kytta-Plasma
f; Kytta-Salbe f; Traumaplant. Switzerland: Kytta Pommade. Venezuela:
Traumaplant.
PROPRIETARY
MULTI-INGREDIENT PREPARATIONS
Czech Republic: Dr Theiss Beinwell Salbe; Stomatosan. Germany:
Kytta-Balsam f; Rhus-Rheuma-Gel N. Israel: Comfrey Plus. Switzerland: Gel a la
consoude; Keppur; Keppur; Kytta Baume. USA: MSM with Glucosamine Creme.
EXTRACTS
Extracts antiinflammatory in vitro and
in vivo, perhaps due to rosmarinic acid (PNC). Allantoin a
well known dermatological agent (PNC). Aqueous extract stimulates release of
prostaglandin-like material from rat gastric mucosa (PNC). Two nonhepatotoxic
PAs, platyphylline and sarracine, have been used for GI hypermotility and
peptic ulceration. Yes, aqueous extracts increase survival time of mice with
spontaneous tumors, and decrease tumor growth, and have antimutagenic activity
(PNC). Is comfrey more likely to cause, cure, or prevent cancer? This is what
we really should be studying.Extracts antiinflammatory in vitro and
in vivo, perhaps due to rosmarinic acid (PNC). Allantoin a
well known dermatological agent (PNC). Aqueous extract stimulates release of
prostaglandin-like material from rat gastric mucosa (PNC). Two nonhepatotoxic
PAs, platyphylline and sarracine, have been used for GI hypermotility and
peptic ulceration. Yes, aqueous extracts increase survival time of mice with
spontaneous tumors, and decrease tumor growth, and have antimutagenic activity
(PNC). Is comfrey more likely to cause, cure, or prevent cancer? This is what
we really should be studying.Extracts antiinflammatory in vitro and
in vivo, perhaps due to rosmarinic acid (PNC). Allantoin a
well known dermatological agent (PNC). Aqueous extract stimulates release of
prostaglandin-like material from rat gastric mucosa (PNC). Two nonhepatotoxic
PAs, platyphylline and sarracine, have been used for GI hypermotility and
peptic ulceration. Yes, aqueous extracts increase survival time of mice with
spontaneous tumors, and decrease tumor growth, and have antimutagenic activity
(PNC). Is comfrey more likely to cause, cure, or prevent cancer? This is what
we really should be studying.
REFERENCE
Barnes, J., Anderson, L. A., and Phillipson, J. D. 2007. Herbal
Medicines Third Edition. Pharmaceutical Press. Auckland and
London.
Duke, J. A. with Mary Jo Bogenschutz-Godwin, Judi duCellier, Peggy-Ann K.
Duke. 2002. Handbook of Medicinal Herbs 2nd Ed. CRC Press
LLC. USA.
Gruenwald, J., Brendler,
T., Jaenicke, Ch. 2000. PDR for Herbal
Medicines. Medical Economics Company, Inc. at Montvale, NJ
07645-1742. USA
Linda S-Roth. 2010. Mosby’s Handbook Of Herbs & Natural
Supplements, Fourth Edition. Mosby Elsevier. USA
Figure
3. Primary Chemical Components and Possible Actions
(Linda, S-R. 2010)
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