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GENTIAN

Botanical Name:	Gentiana lutea
*Family:*	Gentianaceae
*Plant Part Used:*	Root

PRESCRIBING INFORMATION

Actions	Bitter tonic, gastric stimulant, sialagogue, cholagogue
Potential Indications	Based on appropriate evaluation of the patient, practitioners should consider prescribing gentian in formulations in the context of: • Stimulating gastric secretion, bile release from the gallbladder, bile production by the liver (4) • Loss of appetite,^* dyspepsia,^* asthenia, coated tongue, postprandial bloating, in combination with rhubarb (3) • Stimulating gastric secretion, constipation, flatulence, abdominal fullness,^* itching of skin, in combination with rhubarb, cascara, and boldo (3) • Nausea, vomiting, heartburn, abdominal pain, constipation (4) • Stimulating pancreatic enzyme secretion (7)

Contraindications Gastric and duodenal ulcers,¹ hyperacidity,² gastric inflammation³ Warnings and Precautions None required. Interactions None known. Use in Pregnancy and Lactation No adverse effects expected. Side Effects

Very sensitive individuals may occasionally experience headaches.¹

Doses at the higher end of the recommended range in liquid form may cause nausea in some people.

Dosage Dose per day^** Dose per week^** 0.7-2.0 ml of 1:2 liquid extract 5-15 ml of 1:2 liquid extract

* Gentian has also been used in traditional herbal medicine. ESCOP recommends gentian for treating appetite loss and dyspepsia. The Commission E also recommends gentian for abdominal fullness and flatulence. (4,5)

** This dose range is extrapolated from the British Pharmaceutical Codex 1934, the British Pharmacopoeia 1932, and the author’s education and experience.

SUPPORTING INFORMATION

Traditional Prescribing	Traditional Western herbal medicine uses include: • Anorexia (loss of appetite), particularly after feverish conditions, to assist in assimilation of food ³ • Atonic dyspepsia, gastrointestinal atony; debility, gout, amenorrhea ^3,⁴ • Diarrhea, intestinal worms ³
Pharmacologic Research	• Isolated stomach cells exposed to different levels of an extract of gentian showed a concentration-dependent rise in gastric acid production.⁵ • In an experimental model, oral doses of gentian were shown to stimulate secretion of enzymes in the small intestine.⁶ • In another laboratory study, gentian extract increased gastric secretion in a dose-dependent fashion compared with controls. A dose of 0.5 ml/kg had no effect on gastric ulceration.⁷ • Gentian tincture given orally or directly into the stomach increased appetite in an experimental model of cachexia (weight loss in chronic diseases). A marked increase in gastric secretion and its acid and pepsin content was demonstrated only when gentian was given by mouth.⁸ • Gentian extract elevated bronchosecretion when compared with controls in a laboratory study.⁹
Clinical Studies	• In one uncontrolled study involving 18 volunteers using gentian tincture, gastric emptying was slightly increased in 16 of these cases. Gastric evacuation showed no significant change.¹⁰ • Nineteen patients with inflammatory conditions of the gastrointestinal tract associated with elevated IgA levels, and a healthy control group, were given 20 drops of a gentian tincture three times daily for 8 days. Secretory IgA levels were lowered in both groups; a correlation to clinical findings was reported, but statistical analysis was lacking.¹¹ • In healthy volunteers, gentian induced a significant increase in salivary secretion from 1 to 30 minutes after oral administration, similar to the active control (citric acid) and unlike placebo or placebo plus alcohol. From 30 until 120 minutes, the volume per minute of saliva decreased but still remained higher than baseline values. In a doubleblind study, an herbal preparation (containing gentian, rhubarb, cascara, and boldo) was significantly better than placebo for the following symptoms:asthenia, loss of appetite, coated tongue, postprandial bloating, difficult digestion, constipation, flatulence, abdominal fullness, and itching of skin. With regard to the other symptoms investigated, no significant difference was observed. The test preparation was more efficacious than the two pairs of its components (cascara and boldo; gentian and rhubarb).¹² The following herb equivalents were probably administered for the paired preparations:cascara (200 mg/day) and boldo (100 mg/day);gentian (40 mg/day) and rhubarb (200 mg/day). • One oral dose of an alcoholic extract of gentian (containing 0.2 g root) given to volunteers 5 minutes before a meal stimulated gastric secretion, release of bile from the gallbladder and bile production by the liver.¹³ • In a multicenter, uncontrolled study, 205 patients were prescribed on average five gentian capsules per day (equivalent to 600 mg of root). Rapid relief of symptoms such as constipation, flatulence, appetite loss, vomiting, heartburn, abdominal pain, and nausea was achieved.¹⁴ • In Germany, the Commission E supports using gentian to treat digestive disorders, such as loss of appetite, fullness, and flatulence.¹ • ESCOP recommends gentian for treating appetite loss, particularly after illness, and dyspepsia.²

REFERENCES

1 Blumenthal M, et al, editors. The complete German Commission E monographs: therapeutic guide to herbal medicines. Austin: American Botanical Council, 1998.

2 Scientific Committee of the European Scientific Cooperative on Phytotherapy [ESCOP]. ESCOP monographs: Gentianae radix. Argyle House, Gandy Street, Exeter, Devon, EX4 3LS, United Kingdom: European Scientific Cooperative on Phytotherapy, ESCOP Secretariat, July 1997.

3 Felter HW, Lloyd JU. King’s American dispensatory, ed 18. Portland: Eclectic Medical Publications, 1905. rev 3, reprinted 1983

4 British Herbal Medicine Association’s Scientific Committee. British herbal pharmacopoeia. Bournemouth: BHMA, 1983.

5 Gebhardt R. Pharm Pharmacol Lett. 1997;7(2-3):106-108.

6 Kazakov BN. Cited in Scientific Committee of ESCOP: ESCOP monographs: Gentianae radix. Argyle House, Gandy Street, Exeter, Devon, EX4 3LS, United Kingdom: European Scientific Cooperative on Phytotherapy, ESCOP Secretariat, July 1997.

7 Leslie GB. Medita. 1978;8:31-47.

8 Moorhead LD. J Pharmacol Exp Ther. 1915;7:577-589.

9 Chibanguza G, Marz R, Sterner W. Arzneim Forsch. 1984;34(1):32-36.

10 Goetzl FR. Drug Stand. 1956;24:111.

11 Zimmerman W, Gaisbauer G, Gaisbauer M. Z Phytother. 1986;7:59-64.

12 Borgia M, et al. Curr Ther Res. 1981;29(3):525-536.

13 Glatzel H, Hackenberg K. Planta Med. 1967;15(3):223-232.

14 Wegener T. Z Phytother. 1998;19:163-164.

GINGER

Botanical Name:	Zingiber officinale
*Family:*	Zingiberaceae
*Plant Part Used:*	Rhizome

PRESCRIBING INFORMATION

Actions	Carminative, antiemetic, peripheral circulatory stimulant, spasmolytic, antiinflammatory, antiplatelet, diaphoretic, digestive stimulant, pungent
Potential Indications	Based on appropriate evaluation of the patient, practitioners should consider prescribing ginger in formulations in the context of: • Prophylaxis and treatment of nausea and vomiting from motion sickness (2,4) • Prophylaxis and treatment of postoperative nausea (2,4) • Morning sickness (2) • Drug-induced nausea (2) • Osteoarthritis (2) • Dyspepsia (4) • Digestive problems, nausea, vomiting, colic, flatulent dyspepsia, cramping (5) • Fever, the common cold (especially the fresh rhizome), conditions requiring expectoration (5) • Dysmenorrhea (5)

Contraindications According to the Commission E, using ginger is contraindicated in patients with gallstones, except under close supervision. In TCM, dried ginger is used cautiously during pregnancy. A daily dose of 2 g of dried ginger should not be exceeded in pregnancy. Warnings and Precautions The user should proceed with caution in cases of peptic ulceration, gastroesophageal reflux, or other gastric diseases. Interactions Ginger may increase the absorption of pharmaceutical drugs. Although no problems have been reported in humans, ginger may increase the chance of bleeding. Daily doses of (dried) ginger in excess of 4 g should be prescribed with caution in patients who are already taking blood-thinning drugs such as warfarin or aspirin or who have increased risk of hemorrhage. Use in Pregnancy and Lactation No adverse effects are expected within the recommended dose (0.7 to 2.0 ml of 1:2 liquid extract). A daily dose of 2 g of dried ginger should not be exceeded in pregnancy. Ginger has been successfully used in clinical trials to treat pregnant women with nausea. Side Effects At doses approaching or greater than the maximum recommended dose, a blood-thinning effect and an increase in gastric secretory activity leading to heartburn is possible. Topical application of ginger may cause contact dermatitis in sensitive patients. Occupational allergic contact dermatitis from spices, including ginger, has been reported. Dosage Dose per day^* Dose per week^* 0.7-2.0 ml of 1:2 liquid extract 5-15 ml of 1:2 liquid extract

* This dose range is extrapolated from the British Pharmaceutical Codex 1934, the British Herbal Pharmacopoeia 1983, the British Pharmacopoeia 1975, and the author’s education and experience.

SUPPORTING INFORMATION

Traditional Prescribing

Traditional Western herbal medicine uses include:

• Nausea, anorexia, colic, flatulent dyspepsia ^1,²

• Amenorrhea,³ dysmenorrhea;² to improve circulation²

Uses and properties from TCM include:

• For dried ginger:epigastric pain with cold feeling, vomiting and diarrhea with cold extremities, and faint pulse; dyspnea and cough with copious frothy expectoration ⁴

• For fresh ginger:the common cold, vomiting caused by cold in the stomach, cough with thin white sputum ⁴

Pharmacologic Research

Major constituents of ginger rhizome include an essential oil (1% to 3%, containing zingiberene and sesquiphellandrene) and pungent (hot) principles (1.0% to 2.5%, including gingerols and shogaols).

• Several studies have examined the antiemetic and antinausea effects of ginger. The mechanism of action responsible for the antiemetic effect is still controversial, however, possibilities include a central effect via gastrointestinal serotonin antagonism, central and peripheral anticholinergic and antihistaminic effects, and a dampening of induced vestibular impulses to the autonomic centers of the central nervous system.

• Oral administration of spraydried ginger extract significantly prevented ethanol-induced gastric mucosal damage. Ginger and 6-gingerol inhibited experimental gastric ulcers in vivo after oral administration.

• Ginger and its pungent components exert an antiinflammatory effect by inhibiting both the cyclooxygenase and lipoxygenase enzymes belonging to the prostaglandin and leukotriene biosynthetic pathways, respectively. Oral intake of ginger extract inhibited carrageenan-induced paw swelling and was as active as aspirin in this model (although it was devoid of analgesic activity). Essential oil of ginger inhibited chronic adjuvant arthritis when given orally.

• Fever reduction in an experimental model after oral doses of ginger extract was comparable to aspirin.

• Several studies have demonstrated that ginger inhibits platelet aggregation in vitro. The inhibition of thromboxane formation appears to be the main cause of this antiplatelet action of ginger.

• Oral doses of ginger and its constituents have been shown to: increase saliva production, gastric secretions, and activity and intestinal transit; decrease pepsin activity; inhibit gastric contraction and serotonin-induced diarrhea; and reverse the cisplatin-induced delay in gastric emptying.

• Ginger and its components were thermogenic in perfused isolated tissues and significantly inhibited serotonin-induced hypothermia.

• Pungent principles of ginger had antihepatotoxic effects in vitro, inhibited histamine release from mast cells in vitro, and exhibited antiallergic activity in vivo. Ginger, ginger extract, and its pungent principles have demonstrated antioxidant activity in vitro.

• Ginger and its constituents have demonstrated antifungal activity, mild growth inhibition of gram-positive and gram-negative bacteria, antirhinoviral activity, and direct antiparasitic activity, all in vitro.

• Ginger as a thromboxane synthetase inhibitor and prostacyclin agonist was postulated to have therapeutic potential in alcohol withdrawal and the complications of liver damage, recovery from serious burns, peptic ulceration, Kawasaki disease, preventing aging penile vascular changes and impotence, as an antidepressant, and as an analgesic in dysmenorrhea.

Clinical Studies

• A systematic review of randomized controlled trials has evaluated the efficacy of ginger for nausea and vomiting. Six trials conducted before the year 2000 were evaluated. The pooled absolute risk reduction for the incidence of postoperative nausea calculated from three trials indicated a nonsignificant difference between the ginger and placebo groups. The dose was 1 g powdered ginger given preoperatively. Two of these trials suggested that ginger was superior to placebo and equally efficacious as metoclopramide. Three studies (investigating seasickness, morning sickness, and chemotherapy-induced nausea) collectively favored ginger over placebo.⁵ The Cochrane Review of treatments for vomiting of pregnancy suggests ginger may be of benefit (based on two clinical trials) but that the evidence was weak to date (year 2000).⁶

• Many clinical studies have been published documenting the antinausea and antiemetic properties of ginger. However, several clinical studies have also been conducted that produced negative findings. The following summary indicates the trial design, effect on nausea and vomiting (positive-negative), and condition investigated in these trials (see Mills and Bone: Principles and Practice of Phytotherapy). Some of these trials were assessed in the previously listed reviews. Overall, the weight of evidence suggests that ginger may be beneficial for treating nausea and vomiting.

• A positive effect was observed for ginger (0.25 to 1.5 g/day) in: two randomized, double-blind, placebo-controlled trials and one randomized, controlled trial ⁷ investigating seasickness; two randomized, double-blind, controlled trials investigating postoperative nausea; one randomized, double-blind, placebo-controlled, crossover trial in vomiting of pregnancy; one double-blind, controlled trial in hyperketonaemia patients; and one uncontrolled trial of psoralen-induced nausea.

• A negative effect was observed for ginger (0.5 to 1.0 g) in:two controlled trials and one double-blind, controlled trial investigating motion sickness; and one randomized, double-blind, placebo-controlled trial investigating postoperative nausea. A possible criticism of these motion sickness trials is that they were conducted in a laboratory setting that used rotating chairs and other machinery (although other such trials on ginger have been positive).

• A number of trials involving ginger for treating nausea and motion sickness have been conducted since the previously listed reviews.

• A randomized, double-blind, placebo-controlled trial found that treatment with ginger (0.25 g four times/day) provided relief from pregnancy-induced nausea in 76% of women treated. In the placebo group, 46% reported relief. The reduction in nausea was maintained for the 4 days of the trial, and relief often started within 30 minutes of taking the ginger capsule.⁸

• A study involving a small number of healthy volunteers confirmed the efficacy of ginger (1 g) in relieving symptoms of experimentally induced motion sickness. Volunteers who took ginger experienced a greater delay in developing nausea than did the placebo group.⁹

• Symptoms of motion sickness were alleviated in a group of children (4 to 8 years of age) administered ginger before the start of a journey. In the children who were prescribed dimenhydrinate, symptoms were only improved. The ginger group experienced a reduction in symptoms within 30 minutes; for those taking dimenhydrinate the reduction occurred within 60 minutes. Test substances were administered 30 minutes before the start of the journey and every 4 hours thereafter as necessary:ginger powder 250 to 500 mg, dimenhydrinate 12.5 to 25.0 mg. The study was of randomized, double-blind design.¹⁰

• Seventy five percent of arthritis patients (rheumatoid and osteoarthritis) experienced relief in pain and swelling, and all of the patients with muscular discomfort experienced relief of pain, in an uncontrolled clinical study using dried ginger.

• Ginger extract was compared with ibuprofen and placebo in patients with osteoarthritis of the hip or knee in a double-blind, crossover trial. The effect of ginger was mild compared with placebo and was observed only in the first treatment period before crossover.¹¹

• A combination of ginger and Alpinia galanga was tested against placebo in 261 patients with osteoarthritis of the knee. Although significant effects were observed from the herbal treatment, such as reduction in knee pain on standing, the overall benefit was mild. Mild gastrointestinal adverse events occurred more often in the ginger group compared with the placebo group.¹²

• Oral ingestion of ginger improved gastroduodenal motility, both in the fasting state and after a standard test meal, in healthy volunteers who participated in a randomized, placebo-controlled, double-blind, crossover trial.¹³

• Powdered ginger (4 g/day) given to patients with coronary artery disease (CAD) did not affect platelet aggregation, fibrinolytic activity, and fibrinogen levels tested at 1 ¹/₂ and 3 months. No information was provided for controls. However, a single dose of ginger (10 g) produced a significant reduction in platelet aggregation after 4 hours in patients with CAD in a placebo-controlled trial.

• Adding ginger (5 g) to a fatty meal prevented the decrease in fibrinolytic activity caused by the fat intake in a randomized, placebo-controlled, crossover trial involving healthy volunteers. Placebo did not produce this preventative effect.¹⁴

• Treatment with ginger (approximately 2 g) plus soda water dropped the platelet count from 1.8 million to 240,000 in 1 day in a case study of thrombocytosis resulting from a myeloproliferative disorder in a 78-year-old man. The platelet count rose to over 1.5 million when ginger treatment was subsequently withdrawn. In a controlled trial, dried ginger (5 g/day) significantly inhibited platelet aggregation induced by dietary butter supplementation (100 g/day) in healthy males.

• In Germany, the Commission E supports using ginger to treat dyspepsia and prevent motion sickness.¹⁵

• ESCOP recommends ginger for the prophylaxis of the nausea and vomiting of motion sickness and as a postoperative antiemetic for minor day-case surgical procedures.¹⁶

• Ginger has been reinstated to the USP and is official in the USP24-NF19.

REFERENCES

Except when specifically referenced, the following book was referred to in the compilation of the pharmacologic and clinical informationMills S, Bone K. Principles and Practice of Phytotherapy: Modern Herbal Medicine. Edinburgh: Churchill Livingstone, 2000.

1 British Herbal Medicine Association’s Scientific Committee. British herbal pharmacopoeia. Bournemouth: BHMA, 1983.

2 Felter HW. The eclectic materia medica, pharmacology and therapeutics. Portland: Eclectic Medical Publications, 1922. reprinted 1983

3 Grieve M. A modern herbal. New York: Dover Publications, 1971.

4 Pharmacopoeia Commission of the People’s Republic of China. Pharmacopoeia of the People’s Republic of China, English ed. Beijing: Chemical Industry Press, 1997.

5 Ernst E, Pittler MH. Br J Anaesth. 2000;84(3):367-371.

6 Jewell D, Young G. Cochrane Database Syst Rev. (2):2000. CD000145

7 Ribenfeld D, Borzone L. Healthnotes Rev Complement Integr Med. 1999;6(2):98.

8 Eden J: Medical Observer July 21, 2000.

9 Lien HC, Sun WM: Digestive Disease Week 2000, San Diego, May 20-24, 2000.

10 Careddu P. HealthNotes Rev. 1999;6:102-107.

11 Bliddal H, et al. Osteoarthritis Cartilage. 2000;8(1):9-12.

12 Altman RD, Marcussen KC. Arthritis Rheum. 2001;44(11):2531-2538.

13 Micklefield GH, et al. Int J Clin Pharmacol Ther. 1999;37(7):341-346.

14 Verma SK, Bordia A. Indian J Med Sci. 2001;55(2):83-86.

15 Blumenthal M, et al, editors. The complete German Commission E monographs: therapeutic guide to herbal medicines. Austin: American Botanical Council, 1998.

16 Scientific Committee of the European Scientific Cooperative on Phytotherapy [ESCOP]. ESCOP monographs: Zingiberis rhizoma. Argyle House, Gandy Street, Exeter, Devon, EX4 3LS, United Kingdom: European Scientific Cooperative on Phytotherapy, ESCOP Secretariat, March 1996.

GINKGO

Botanical Name:	Ginkgo biloba
*Family:*	Ginkgoaceae
*Plant Part Used:*	Leaf

PRESCRIBING INFORMATION

Actions	Antioxidant, antiplatelet activating factor (anti-PAF) activity, tissue perfusion enhancing, circulatory stimulant, cognition enhancing, neuroprotective
Potential Indications	Based on appropriate evaluation of the patient, practitioners should consider prescribing Ginkgo in formulations in the context of: • Cerebral insufficiency (restricted cerebral blood flow) and its related symptoms, such as memory and cognitive impairment, dizziness, tinnitus, acute cochlear deafness, headaches, anxiety and depression, and fatigue (1,4) • Early stages of primary degenerative dementia (Alzheimer’s-type) (1,4) • Multiinfarct (vascular) dementia (2,4) • Stroke of recent onset (2) • A tonic for older adults (2) • Vertigo or dizziness of vascular origin (2) • Tinnitus of vascular and involutional origin (4) • Peripheral arterial occlusive disease (Fontaine stage II [intermittent claudication] or stage III) (1,4) • Idiopathic sudden hearing loss (2) • Disorders resulting from reduced retinal blood flow, senile macular degeneration (3) • Enhancing cognitive function, including working and long-term memory, abstract reasoning, and processing speed in healthy individuals and particularly in older adults (2) • Improving attention in healthy young individuals (3) • Improving memory and cognitive performance in healthy individuals (2) • The effects of high altitude or hypoxia (2) • Antioxidant activity (3) • Congestive dysmenorrhea (3) • Anti-PAF activity (4a) • Asthma (4)

Contraindications None known. Warnings and Precautions Ginkgo should be used with caution in patients on anticoagulant or antiplatelet medication. Interactions Based on some case reports of possible interaction, caution should be exercised when prescribing Ginkgo with warfarin and aspirin. Use in Pregnancy and Lactation No adverse effects expected. Side Effects

Analyses of clinical trials have shown that Ginkgo has a remarkably low incidence of side effects. Isolated episodes of spontaneous bleeding attributed to intake of Ginkgo have been reported. However, a clinical trial (see later discussion) found that treatment with Ginkgo limited oxidative stress in cardiovascular surgery because of a membrane-protective effect. Recovery of Ginkgo-treated patients was slightly improved compared with untreated patients.

A case of Stevens-Johnson syndrome that appeared to be associated with use of tablets containing standardized Ginkgo extract, choline, and B vitamins was reported. The authors advised that the reaction was unlikely to have been caused by the choline or B vitamins.¹ (Stevens-Johnson syndrome is an acute inflammatory skin disease that affects the skin and mucous membranes of the face and mouth.)

Dosage Dose per day^* Dose per week^* 3-4 ml of the standardized (2:1) liquid extract 21-28 ml of the standardized (2:1) liquid extract Extracts providing standardized levels of ginkgo flavone glycosides are recommended. Ideally, aqueous ethanol extracts should contain 9.6 mg/ml of ginkgo flavone glycosides. No restriction was found on the long-term use of Ginkgo. However, Ginkgo should be recommended for at least 6 weeks before any assessment of clinical benefit is made.

* This dose range is based on those used in clinical trials.

SUPPORTING INFORMATION

Traditional Prescribing

No information has been found for the traditional use of Ginkgo leaf. Ginkgo nuts were used in TCM.

Pharmacologic Research

Pharmacologic and clinical studies usually tested a special concentrated standardized extract of Ginkgo leaves, which is chemically complex, containing at least 26 identified components. The 50:1 concentrated extract is standardized to contain 22.5% to 25.0% flavonoid glycosides (ginkgo flavone glycosides) and 6% to 8% terpenoids (ginkgolides and bilobalide).

• The ginkgolides are potent and specific PAF antagonists; the effects are long-lived and are rapidly established after oral doses.

• Many experimental models have demonstrated the preventative and protective effects of standardized Ginkgo extract (high doses) and ginkgolides against hypoxia- or ischemia-induced damage of cerebral and cardiovascular tissues, both in vitro and in vivo after oral administration.

• Standardized Ginkgo extracts have demonstrated potent antioxidant activity in many in vitro models.

• Prior oral dosing with standardized Ginkgo extract enhanced the performance of a tested task, indicating improved retrieval of the learned response, in a well-controlled animal study. Oral administration of standardized Ginkgo extract to young and old rats facilitated behavioral adaptation despite adverse environmental influences.

• Oral administration of standardized Ginkgo extract in conjunction with a high-fat diet reduced disturbances of lipid metabolism and the severity of plaque formation in an experimental model when compared with placebo and rutin. Ginkgo also affected metabolic processes in the liver and may modify lipid deposition in major arteries.

• Chronic administration of standardized Ginkgo extract inhibited stress-induced corticosterone hyposecretion through a reduction in the number of adrenal peripheral benzodiazepine receptors. Ginkgo extract and ginkgolide B were also found to act at the hypothalamic level and were able to reduce corticotropin-releasing hormone expression and secretion.

• Intragastric administration of a combined preparation of standardized extracts of Ginkgo and ginger demonstrated anxiolytic effects comparable to diazepam injection in vivo.

• Ginkgo extract fractions relaxed penile corpus cavernosal tissues in vitro, an effect that may help maintain erection.

• Topical application of standardized Ginkgo extract had antiinflammatory activity comparable to indomethacin in the croton oil test and promoted hair regrowth in shaved mice.

Clinical Studies

The following clinical trials were conducted using a standardized Ginkgo extract (50:1), with the majority of trials employing a daily dose range of 120 to 160 mg, which equates to 6 to 8 g of original dried herb (or 3 to 4 ml of a 2:1 standardized liquid extract).

• A critical review of 40 clinical trials conducted from 1975 to 1991 on the clinical use of standardized Ginkgo extracts in patients with cerebral insufficiency and related conditions (primary degenerative dementia; dizziness associated with labyrinth, vestibular disorders, or both; acute cochlear deafness; senile cognitive decline; and tinnitus) found that all except one of the 40 trials showed positive results, with significant results in 26. The inconclusive result was obtained for a trial on senile dementia of vascular origin. In most of the trials, the daily dose was 120 to 160 mg of standardized extract, given for at least 4 to 6 weeks. Meta-analysis of 11 randomized, double-blind, placebo-controlled trials confirmed the global effectiveness of Ginkgo in five studies and concluded that standardized Ginkgo extract provides a better therapeutic effect compared with placebo in treating cerebral insufficiency. In most cases, 150 mg/day was administered for 12 weeks. A more recent review confirmed these results and noted that no significant differences in the frequency or types of side effects were observed between Ginkgo and placebo groups.²

• Improvements in cerebral blood flow, motor recovery, intellectual performance, memory, mood, and behavior were observed in recent stroke victims after treatment with standardized Ginkgo extract in uncontrolled and in randomized, double-blind, placebo-controlled, and comparative trials. Although the general dosage used was 120 mg/day of standardized extract for 1 to 2 months, in one of these trials, some patients received up to 360 mg/day.

• A meta-analysis of four randomized, double-blind, placebo-controlled trials found a small but significant effect after 3 to 6 months treatment with 120 to 240 mg/day of standardized Ginkgo extract on objective measures of cognitive function in patients with Alzheimer’s disease. A subsequent randomized, double-blind, placebo-controlled, multicenter trial in patients with mild to severe Alzheimer’s disease or multiinfarct dementia found that, compared with baseline values, treatment with standardized Ginkgo extract (120 mg/day for 26 weeks) slightly improved daily living and social behavior and cognitive assessment. The placebo group showed a statistically significant worsening in all domains of assessment. Regarding safety, no differences between Ginkgo and placebo were observed.³ Two randomized, double-blind trials (included in the previously mentioned meta-analysis) demonstrated that standardized Ginkgo extract improved the cognitive performance and social function of patients with mild to severe Alzheimer’s disease or multiinfarct dementia compared with placebo. No significant difference compared with placebo was observed in the number of patients reporting adverse events or in the incidence and severity of these events. The dosage administered in these trials was 240 mg/day for 24 weeks and 120 mg/day for 52 weeks. A recent meta-analysis found no major differences between standardized Ginkgo extract and four cholinesterase inhibitors (tacrine, donepezil, rivastigmine, and metrifonate) for delaying symptom progression in Alzheimer’s disease or response rate compared with placebo. The authors suggested that all treatments compared were equally efficacious in treating mild to moderate Alzheimer dementia.⁴

• In contrast, results from a randomized, double-blind, placebo-controlled, parallel-group, multicenter trial published in 2000 suggest that Ginkgo is not efficacious as is a treatment for older people with age-associated memory impairment or mild to moderate Alzheimer’s or vascular dementia. Patients were randomized to receive placebo or standardized Ginkgo extract in one of two doses: 160 mg/day or 240 mg/day for 12 or 24 weeks.⁵ However, given the mixed nature of the participants in this trial, its significance can be questioned.

• Supplementation with standardized Ginkgo extract (120 mg/day for 4 months) improved mood, sleep, and coping ability for daily activities in a randomized, placebo-controlled study involving 5028 free-living elderly volunteers.⁶

• In a randomized, double-blind, placebo-controlled study involving healthy adults, standardized Ginkgo extract (100 mg/day for 30 days) produced a significant improvement in a wide range of cognitive abilities, including long-term memory and abstract reasoning, using the multidimensional aptitude battery. Standardized Ginkgo extract (180 mg/day for 6 weeks) significantly increased cognitive processing speed and subjective ratings of memory improvement, compared with placebo, in cognitively intact older adults (55 to 86 years of age) in a randomized, double-blind, placebo-controlled, parallel-group study.⁷ The effects of acute doses of standardized Ginkgo extract on memory and psychomotor performance in asymptomatic volunteers aged 30 to 59 years was tested in a randomized, double-blind, placebo-controlled, five-way crossover design. The results confirm that the effects of Ginkgo on cognition are more pronounced for memory, particularly working memory. The most efficacious dose was a single dose of 120 mg and the cognitive enhancing effects were more likely to be apparent in individuals aged 50 to 59 years.⁸ In a double-blind, controlled, crossover trial, acute administration of standardized Ginkgo extract (240 mg and 360 mg) to healthy young volunteers produced a sustained improvement in attention compared with placebo.^9,¹⁰ A randomized, double-blind, placebo-controlled trial demonstrated significant improvement in speed of information processing, working memory, and executive processing for healthy volunteers treated with standardized Ginkgo extract.¹¹ A combination containing standardized extracts of Ginkgo (120 mg/day) and Korean ginseng (200 mg/day standardized to 4% ginsenosides) demonstrated improvement in the working and long-term memories of healthy middle-aged volunteers after 14 weeks in a multicenter, double-blind, placebo-controlled trial.¹²

• In a meta-analysis that included five placebo-controlled trials, standardized Ginkgo extract (120 to 160 mg/day for 4 to 6 weeks) was found to have a highly significant therapeutic effect over placebo in peripheral arterial occlusive disease (Fontaine stage II or III). A review of randomized, double-blind, placebo-controlled trials of either standardized Ginkgo extract (120 to 160 mg/day) or the drug pentoxifylline in treating intermittent claudication found that the trials had similar clinical outcomes and were of the same methodological quality. Eight randomized, double-blind, placebo-controlled trials were included in a recent meta-analysis, concluding that standardized Ginkgo extract was superior to placebo in the symptomatic treatment of patients with intermittent claudication. The daily dose in these trials ranged from 120 mg to 160 mg for a period of 24 weeks in six of the trials and for a shorter duration in the other trials.¹³

• A review of randomized controlled trials found inconsistent results for Ginkgo in treating patients with tinnitus without accompanying symptoms of cerebral insufficiency.¹⁴ A large, double-blind, placebo-controlled trial published in early 2001 found that standardized Ginkgo extract (150 mg/day) was no more beneficial than was placebo in treating tinnitus. The treatment did not significantly affect other symptoms of cerebral insufficiency. Given the positive results of previous trials, the authors suggested that Ginkgo appears ineffective in treating tinnitus alone, but it may be effective in treating tinnitus in patients who also have other symptoms of cerebral insufficiency.¹⁵

• A randomized trial comparing standardized Ginkgo extract (160 mg/day) and betahistine (a vasodilator, 32 mg/day) demonstrated the efficacy of both treatments on subjective and objective measurements of equilibrium in patients complaining of vertigo, dizziness, or both caused by vascular vestibular disorders. The results indicated that the sites of action of Ginkgo and betahistine for compensation of equilibrium are different and that Ginkgo improved oculomotor and visuovestibular function to a greater extent.¹⁶

• A significant borderline benefit for Ginkgo over naftidrofuryl (a vasodilator) in idiopathic sudden hearing loss (existing no longer than 10 days) was shown after 3 weeks’ treatment in a randomized, comparative study. Ginkgo treatment was preferred because of the lack of side effects. Both treatment groups also received infusion therapy.

• A randomized, double-blind, placebo-controlled trial found standardized Ginkgo treatment (containing 48 mg/day flavone glycosides for 10 weeks) was unable to prevent the development of the symptoms of winter depression (the most prevalent type of seasonal affective disorder).¹⁷ Standardized Ginkgo extract (240 mg/day) improved sleep in patients with major depression. In this open, pilot trial, patients taking the antidepressant trimipramine plus Ginkgo were compared with those taking the drug alone.¹⁸

• In a multicenter, double-blind, placebo-controlled study, Ginkgo significantly improved breast tenderness and markedly improved edema, anxiety, depression, and headaches in 165 women with congestive symptoms of PMS. Standardized Ginkgo extract was administered at 160 mg/day from day 16 to day 5 of the next menstrual cycle.

• In patients with blockage of veins in the retina, standardized Ginkgo extract improved blood vessels, visual acuity, field of vision, near and far vision, and color recognition in a randomized, double-blind, placebo-controlled trial. Marked improvements in vision in 86% of patients with poor blood supply to the retina (or the areas of the brain that interpret the signals from the eyes) were observed in an uncontrolled trial. The dosage of standardized extract was 120 mg/day for 3 months. A small, double-blind, placebo-controlled trial found standardized Ginkgo treatment (160 mg/day for 6 months) improved visual acuity (compared with placebo) in patients with senile macular degeneration. A recent placebo-controlled study found acute administration of Ginkgo significantly increased end-diastolic velocity in the ophthalmic artery in healthy volunteers, indicating possible benefit for optic neuropathy linked to glaucoma and other ischemic ocular diseases. The dosage of standardized Ginkgo extract was 120 mg/day for 2 days.¹⁹

• In a randomized, placebo-controlled trial, administering standardized Ginkgo extract (160 mg/day) for the duration of an expedition significantly prevented acute mountain sickness at moderate altitude (5400 meters, or over 17,700 feet) and decreased vasomotor disorders of the extremities.

• Ingestion of standardized Ginkgo extract (120 mg/day for 3 months) by healthy volunteers resulted in the inhibition of collagen-induced platelet aggregation and reduced urinary excretion of 11-dehydrothromboxane B₂ (a metabolite of thromboxane A₂).²⁰

• A high dose of ginkgolide mixture (120 mg) inhibited PAF activity in healthy human volunteers in a small, double-blind, placebo-controlled study. The mixture contained 40% ginkgolide A, 40% ginkgolide B, and 20% ginkgolide C.

• Ginkgo limited free radical–induced oxidative stress generated throughout surgery in patients undergoing aortic valve replacement in a double-blind, placebo-controlled study. The dosage prescribed was 320 mg/day of standardized extract for 5 days before surgery.

• In small, uncontrolled trials standardized Ginkgo extract has:

• Significantly reduced fibrinogen levels and blood viscosity in out-patients with a long history of elevated levels (240 mg/day for 12 weeks)

• Increased hypoxia tolerance in healthy volunteers (200 mg/day for 1 week)