• Clinical data 90%
  • Efficacy 80%
  • Security 70%
  • Toxicity 30%

Mentha x piperita
Overground parts of Mentha x piperita

Synonyms

Mentha piperita (L.) Huds., M. piperita Stokes, M. balsamea Willd.

General appearance

A colourless, pale yellow or pale greenish-yellow liquid.

Major chemical constituents 

The major constituents are menthol (30–55%) and menthone (14–32%). Menthol occurs mostly in the free alcohol form, with small quantities as the acetate (3–5%) and valerate esters. Other monoterpenes present include isomenthone (210%), 1,8-cineole (6–14%), a-pinene (1.0–1.5%), b-pinene (1–2%), limonene (1–5%), neomenthol (2.5–3.5%) and menthofuran (1–9%).

Medicinal uses of Mentha piperita

Uses supported by clinical data
Internally for symptomatic treatment of irritable bowel syndrome, and digestive disorders such as flatulence and gastritis (21–23). Externally for treatment of myalgia and headache.
Uses described in pharmacopoeias and in traditional systems of medicine
Internally and externally for the symptomatic treatment of catarrh and coughs.
Uses described in folk medicine, not supported by experimental or clinical data
Treatment of dysentery, diabetes, dysmenorrhoea, fevers, jaundice and urinary infections.

Pharmacology

Experimental pharmacology

Antimicrobial activity

Aetheroleum Mentha Piperita inhibited the growth in vitro of Staphylococcus aureus, Pseudomonas aeruginosa, Bacillus subtilis, Enterococcus faecalis and Escherichia coli, but did not affect the growth of Bacillus cereus, Penicillium cyclopium or Aspergillus aegyptiacus. The essential oil inhibited the growth in vitro of Trichophyton equinum and T. rubrum (at a concentration of 0.4mg/ml), Aspergillus flavus, A. fumigatus and A. niger.

Antispasmodic activity

The essential oil had smooth muscle relaxant activity in guinea-pig ileum (ED5026.0 mg/l) and trachea (ED50 87.0 mg/l) in vitro, and inhibited electrically induced contractions of guinea-pig ileum (IC50 0.176 mg/ml) in vitro. The essential oil decreased both the number and amplitude of spontaneous contractions, and inhibited spasms induced by barium chloride, pilocarpine and physostigmine in isolated segments of rabbit and cat ileum (inhibitory concentrations 0.05mg/ml). The essential oil (0.5mmol/l) inhibited smooth muscle contractions of guinea-pig ileum in vitro induced by barium chloride, carbachol, histamine and potassium chloride. Both the essential oil and menthol act as calcium antagonists, since they inhibited the influx of calciumions through smooth muscle of guinea-pig ileum and taenia coli isolated from humans. The essential oil and menthol inhibited smooth muscle contractions of guinea-pig ileum induced by potassium chloride (IC50 28.1 and 21mg/ml, respectively) and induced electrically (11.5 and 7.7mg/ml, respectively). Both also inhibited 45Ca2+ uptake induced by potassium ion-dependent depolarization in brain synaptosomes and retinal neurons, and inhibited specific binding of [3H]nitrendipine to ileal smooth muscle, synaptosomes and retinal neurons. The essential oil relaxed carbachol-contracted guinea-pig taenia coli (IC50 22.1mg/ml), and inhibited spontaneous contractions in isolated guinea-pig colon (IC50 25.9mg/ml) and rabbit jejunum (IC50 15.2mg/ml). The essential oil also attenuated contractile responses in guinea-pig taenia coli induced by acetylcholine, histamine, serotonin (5-hydroxytryptamine) and substance P. Contraction of Oddi’s sphincter induced by morphine was reversed after intravenous administration of the essential oil to guinea-pigs (1.0 mg/kg body weight). However, intravenous injection of the essential oil to guinea-pigs (25mg/kg body weight) was found to increase spasms of the sphincter. Intragastric administration of the essential oil exhibited cholagogic activity in rats. This activity was attributed to (-)-menthol, a major constituent of the essential oil.

Antifoaming activity

The essential oil (0.1%) had antifoaming and carminative activity in vitro; however, the antifoaming effect was less than that observed with a combination of dimethicone and silica.

Toxicology

Intragastric administration of the essential oil (100mg/kg body weight) to rats daily for 28 days induced histopathological changes (scattered cyst-like spaces) in the white matter of the cerebellum. No behavioural or clinical symptoms due to the encephalopathy were observed.

Clinical pharmacology

Antispasmodic activity

Irritable bowel syndrome

Aetheroleum Menthae Piperitae is a carminative with antispasmodic activity that reduces intracolonic pressure. In an open study of 20 patients, an aqueous suspension of peppermint oil (British Pharmacopoeia Standard) injected al ng the biopsy channel of a colonoscope relieved colonic spasms within 30 seconds, allowing easier passage of the instrument or facilitating polypectomy. The essential oil relaxed the oesophageal sphincter when administered orally (15 drops [about 0.88 ml] oil in 30 ml water), decreasing the pressure differential between the stomach and oesophagus, and allowing reflux to occur. In a double-blind, placebo-controlled, crossover clinical trial, 18 patients with symptoms of irritable bowel syndrome were treated daily with three entericcoated gelatin capsules, each containing either 0.2 ml essential oil or a placebo for 3 weeks. Patients reported feeling significantly better while taking capsules containing the essential oil than when taking those containing placebo (P <0.01) and considered the essential oil significantly better than the placebo in relieving abdominal symptoms (P < 0.005). These results were confirmed in a later study. A matched-pair, placebo-controlled trial assessed the efficacy of the essential oil in the treatment of 40 patients with symptoms of irritable bowel syndrome. After 14 days of treatment with 1–2 enteric-coated gelatin capsules containing either 0.2 ml essential oil or a placebo three times daily, patients treated with the essential oil showed an increase in intestinal transit time, and subjective improvement in the feeling of fullness, bloating, bowel noises and abdominal pain, as compared with patients who received the placebo. Administration of the essential oil to patients undergoing barium enemas relieved the associated colonic spasms. However, two earlier trials failed to confirm the antispasmodic and analgesic activity of the essential oil in the associated colonic spasms. However, two earlier trials failed to confirm the antispasmodic and analgesic activity of the essential oil in the treatment of irritable bowel syndrome. A double-blind, placebocontrolled trial assessed the effects of peppermint oil in 34 patients with symptoms of irritable bowel syndrome. After 4 weeks of treatment with two capsules containing either 0.2 ml essential oil or a placebo three times daily, patients treated with the essential oil showed no significant difference in their overall symptoms, as compared with those who received the placebo treatment.
A prospective, randomized double-blind, placebo-controlled trial assessed the efficacy and safety of enteric-coated capsules containing 0.2ml essential oil (one capsule 3–4 times daily for 1 month) for the symptomatic treatment of 110 patients with irritable bowel syndrome. After treatment, 79% of patients in the treatment group and 43% of those in the placebo group experienced alleviation of severe abdominal pain; 83% of the treated group and 32% of the placebo group had reduced abdominal distention and a reduced stool frequency; 73% of the treated group and 31% of the placebo group had fewer bowel noises; and 79% of the treated group and 22% of the placebo group had less flatulence.
A review of five randomized, double-blind, placebo-controlled clinical trials assessed the efficacy of the essential oil in the symptomatic treatment of irritable bowel syndrome. By measuring the improvement of symptoms, the meta-analysis showed that two of the trials  did not show a significant difference between the essential oil and the placebo. However, three of the trials demonstrated significant improvements in symptoms after treatment with the essential oil. Although there were methodological flaws in most of the trials analysed, the analysis suggested that there was a significant positive effect of the essential oil (P < 0.001) on the symptomatic treatment of irritable bowel syndrome, as compared with the placebo.

Dyspepsia

A double-blind, placebo-controlled multicentre study involving 45 patients with non-ulcer dyspepsia assessed the change in pain intensity and Clinical Global Impression Scale after treatment with an enteric-coated capsule containing a combination of the essential oil (90 mg) and caraway oil (50 mg). After 4 weeks of treatment with the essential oil/caraway oil capsules (one capsule three times daily), 63% of patients were free of pain; 89.5% had less pain; and 94.5% showed improvements in the Clinical Global Impression Scale. In another study, oral administration of the essential oil (0.2 ml) delayed the gastric emptying time in healthy volunteers and in patients with dyspepsia.

Analgesic activity

A randomized, double-blind, placebo-controlled, crossover study assessed the efficacy of a combination product of the essential oil (peppermint oil) and Aetheroleum Eucalypti (eucalyptus oil) for headache relief in 32 patients. Five different preparations were used (all in 90% ethanol, to a final weight of 100g): 10 g peppermint oil and 5 g eucalyptus oil; 10 g peppermint oil and traces of eucalyptus oil; traces of peppermint oil and 5 g eucalyptus oil; and traces of both peppermint oil and eucalyptus oil; or a placebo. The test preparations or placebo were applied topically to large areas of the forehead and temples, and the effects on neurophysiological, psychological and experimental algesimetric parameters were measured. The preparations improved cognitive performance, and induced muscle relaxation and mental relaxation, but had no effect on sensitivity to head ache. A randomized, double-blind, placebo-controlled study assessed the efficacy of the essential oil in the treatment of 41 patients suffering from chronic tension headache. At each headache episode, patients were treated orally with two capsules of either paracetamol (1 g) or placebo, or exter-nal application of 10% essential oil in ethanol, or a placebo solution. Compared with the placebo solution, the 10% essential oil preparation produced a significant (P < 0.05) reduction in headache intensity within 15 minutes. Paracetamol was also more effective than the oral placebo but did not differ significantly from topical treatment with the essential oil.

Contraindications

Preparations of Aetheroleum Menthae Piperitae should not be used internally by patients with inflammation of the gastrointestinal tract or gall bladder, or with impaired liver function. Hypersensitivity to the essential oil has been reported.

Warnings

Aetheroleum Menthae Piperitae preparations should not be applied to the face, especially the nose, of infants or young children. Keep out of reach of children.

News and Journals

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