Diosmin

Overview

Diosmin is a flavone glycoside found primarily in the rinds of citrus fruits, particularly hesperidin-rich varieties. It is semi-synthetically produced from hesperidin through an oxidation process and has been used as a pharmaceutical agent in Europe since the 1960s, most commonly in micronized purified flavonoid fraction (MPFF) formulations combined with hesperidin. Diosmin is classified as a venoactive drug and is prescribed for the symptomatic treatment of chronic venous disease.

The pharmacological effects of diosmin center on its ability to improve venous tone, reduce capillary permeability, and exert anti-inflammatory activity. It enhances venous return by prolonging the vasoconstrictive effect of norepinephrine on the vein wall and inhibits the inflammatory cascade by reducing leukocyte adhesion and migration. These properties make it effective for managing symptoms of chronic venous insufficiency, including leg heaviness, pain, swelling, and restless legs, as well as acute hemorrhoidal episodes.

Clinical evidence supporting diosmin is robust, with multiple randomized controlled trials and meta-analyses demonstrating significant improvements in venous disease symptoms and accelerated healing of venous leg ulcers. The standard therapeutic dose is 900 to 1,000 mg daily in the micronized form, which offers superior bioavailability compared to non-micronized preparations. Diosmin is well tolerated, with gastrointestinal discomfort being the most commonly reported side effect.

Mechanism of Action

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Venotonic Mechanism — Norepinephrine Pathway\n\nDiosmin is a naturally occurring flavonoid glycoside (diosmetin-7-O-rutinoside) found in citrus peels. Its primary pharmacological action is as a venotonic agent that increases venous wall tone through inhibition of catechol-O-methyltransferase (COMT) and norepinephrine reuptake in venous smooth muscle. By prolonging norepinephrine availability at a1-adrenergic receptors in the venous wall, diosmin increases smooth muscle contraction and reduces venous distensibility and capacitance (PMID: 10721976).\n\n

Microvascular Protection & Lymphatic Drainage\n\nDiosmin reduces capillary hyperpermeability by inhibiting prostaglandin E2 and thromboxane A2 synthesis while increasing PGF2a production. It strengthens capillary resistance by stabilizing the collagen-integrin anchoring complex between endothelial cells and the basement membrane. Diosmin also enhances lymphatic contractility and pumping frequency, improving lymphatic drainage and reducing edema (PMID: 12453236).\n\n

Anti-Inflammatory Leukocyte Adhesion Inhibition\n\nDiosmin inhibits leukocyte-endothelial adhesion by downregulating expression of adhesion molecules including ICAM-1, VCAM-1, and selectins on endothelial surfaces. It suppresses neutrophil activation and free radical generation by inhibiting NADPH oxidase and reducing complement activation. This mechanism is particularly relevant in chronic venous insufficiency, where leukocyte trapping and activation in the venous microcirculation drives tissue damage (PMID: 12927940).\n\n

Rheological & Erythrocyte Effects\n\nMicronized diosmin (MPFF formulation, combined with hesperidin) improves red blood cell deformability and reduces blood viscosity, improving microcirculatory flow. It also inhibits platelet aggregation through suppression of phosphodiesterase activity and modulates the prostaglandin/thromboxane balance toward antithrombotic pathways."

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Research

Safety Profile

Common Side Effects

• Generally well-tolerated at standard doses (500–1000 mg/day) with a favorable safety profile
• Mild gastrointestinal symptoms including stomach pain, nausea, diarrhea, or abdominal cramps reported in a small percentage of users
• Headache and dizziness occur infrequently
• Mild skin rash or allergic dermatitis in sensitive individuals

Serious Adverse Effects

• Rare cases of severe allergic reactions including angioedema have been reported
• Isolated reports of muscle pain or general malaise, though causation has not been definitively established
• No significant organ toxicity has been observed in clinical studies lasting up to 12 months
• Very high doses may theoretically contribute to gastrointestinal bleeding risk when combined with other vasoactive agents

Contraindications

• Known hypersensitivity to diosmin, hesperidin, or other flavonoids warrants avoidance
• Pregnant women should avoid use in the first trimester; use in the second and third trimesters should occur only under medical supervision for conditions such as hemorrhoids or venous insufficiency
• Breastfeeding women should exercise caution due to limited safety data on excretion in breast milk
• Patients with active bleeding disorders should consult a physician before use

Drug Interactions

• May potentiate the effects of anticoagulant and antiplatelet medications (warfarin, heparin, clopidogrel, aspirin), increasing bleeding risk
• Known inhibitor of CYP1A2 and CYP3A4 enzymes, which may increase serum levels of drugs metabolized by these pathways, including certain statins, calcium channel blockers, and benzodiazepines
• May interact with metformin and other antidiabetic agents due to mild effects on glucose metabolism
• Potential interaction with iron supplements, as flavonoids can chelate iron and reduce its bioavailability
• May enhance the effects of venoactive drugs and compression therapy when used concomitantly

Population-Specific Considerations

• Widely prescribed in Europe (as Daflon) for chronic venous insufficiency and hemorrhoids with extensive clinical safety data
• Older adults with polypharmacy should have their medication list reviewed for potential cytochrome P450 interactions
• Patients scheduled for surgery should discontinue at least two weeks prior due to mild antiplatelet activity
• Renal and hepatic dosing adjustments are generally not required at standard doses

Pharmacokinetic Profile