Intravenous (IV) glycyrrhizin — a triterpene saponin derived from the root of the licorice plant (Glycyrrhiza glabra) — has been used in clinical medicine for decades, most notably in Japan and parts of Asia. Known commercially as Stronger Neo-Minophagen C (SNMC), IV glycyrrhizin has accumulated a substantial body of evidence supporting its hepatoprotective, anti-inflammatory, antiviral, immunomodulatory, and even anticancer properties.
This Blog explores the science-backed benefits of IV glycyrrhizin, how it works, who may benefit, and what safety considerations clinicians and patients should know.
What Is IV Glycyrrhizin?
Glycyrrhizin is the principal bioactive compound in licorice root, a triterpene that is 30 to 50 times sweeter than sugar. While oral licorice has been used in traditional medicine for over 4,000 years, the intravenous formulation — Stronger Neo-Minophagen C (SNMC) — was developed in Japan and contains 2% glycyrrhizin, 0.1% cysteine, and 2% glycine. IV administration bypasses the gastrointestinal tract, delivering glycyrrhizin directly into the bloodstream for higher bioavailability and more predictable pharmacokinetics.
Top Benefits of IV Glycyrrhizin
1. Hepatoprotection and Liver Enzyme Reduction
The most well-established clinical benefit of IV glycyrrhizin is its ability to protect the liver and reduce elevated liver enzymes. In a phase 3 randomized, double-blind, placebo-controlled trial, patients with chronic hepatitis C who received IV glycyrrhizin (administered 3 or 5 times per week for 12 weeks) showed a significantly higher proportion achieving greater than 50% reduction in ALT levels compared to placebo. After 52 weeks, approximately 45–46% of treated patients demonstrated reduced necroinflammation on liver biopsy.
Glycyrrhizin preparations exert hepatoprotective activity through multiple mechanisms: anti-inflammatory, membrane-stabilizing, antioxidant, anti-apoptotic, immunomodulatory, and anti-fibrotic effects.
2. Prevention of Hepatocellular Carcinoma (HCC)
One of the most compelling long-term benefits of IV glycyrrhizin is its potential to reduce the risk of liver cancer. A landmark cohort study of 1,249 patients with chronic hepatitis C found that long-term IV glycyrrhizin therapy significantly decreased the hepatocarcinogenesis rate, with a hazard ratio of 0.49 (95% CI: 0.27–0.86). Cumulative HCC incidence at 15 years was 12% in the treated group versus 25% in controls.
Additionally, liver cirrhosis occurred less frequently in patients on long-term SNMC therapy (28% vs. 40% at 13 years).
3. Broad-Spectrum Antiviral Activity
Glycyrrhizin demonstrates antiviral activity against a wide range of viruses, including:
- Hepatitis A, B, and C viruses
- HIV type 1
- Herpes simplex virus
- Influenza A
- SARS-related coronaviruses (including SARS-CoV-2)
- Respiratory syncytial virus
- Varicella zoster virus
The antiviral mechanism involves inhibition of viral replication, direct viral inactivation, suppression of HMGB1/TLR4-mediated inflammation, and stimulation of endogenous interferon-alpha production.
4. Potent Anti-Inflammatory Effects
IV glycyrrhizin exerts powerful anti-inflammatory effects through multiple pathways:
- Inhibition of NF-κB and MAPK signaling cascades
- Suppression of pro-inflammatory cytokines (IL-1β, IL-6, TNF-α, IL-8, IL-17)
- Blockade of COX-2 and prostaglandin E2 synthesis
- Inhibition of HMGB1, a key signaling molecule in acute and chronic inflammation
- Attenuation of TLR3, TLR4, and TLR9 receptor-mediated inflammatory responses
These mechanisms make glycyrrhizin relevant not only for liver disease but also for systemic inflammatory conditions.
5. Immunomodulatory Properties
Glycyrrhizin functions as a bidirectional immune modulator — it suppresses harmful inflammatory cascades while selectively enhancing protective immune responses. Specifically, it:
- Promotes T-cell differentiation toward the Th1 subset via dendritic cell modulation
- Enhances natural killer (NK) cell activity
- Stimulates interferon (IFN) production
- Augments IL-2 production to support lymphocyte growth
- Modulates the Th17/Treg balance
6. Antioxidant Protection
Glycyrrhizin and its metabolite glycyrrhetinic acid function as potent antioxidants, protecting cells from oxidative stress. This is particularly relevant in liver disease, where oxidative damage drives fibrosis progression and carcinogenesis. Glycyrrhizin increases hepatic glutathione levels and protects hepatocytes from toxin-induced damage.
7. Survival Benefit in Hepatic Failure
In patients with hepatitis-related hepatic failure, SNMC therapy demonstrated a striking survival advantage: 72% of patients treated with SNMC for 12 weeks survived, compared to only 31% receiving standard supportive therapy.
How Does IV Glycyrrhizin Work? Mechanism of Action
Glycyrrhizin's therapeutic effects stem from its multi-target pharmacological profile:
- HMGB1 Inhibition: Glycyrrhizin directly binds to the Box B domain of HMGB1, interfering with its engagement with TLR4 and RAGE receptors, thereby blocking downstream NF-κB, MAPK, and NLRP3 inflammasome pathways.
- Membrane Interaction: Glycyrrhizin interacts with the lipid bilayer of cell membranes, attenuating receptor-mediated signaling and reducing cellular uptake of inflammatory stimuli.
- Cytochrome P450 Induction: Glycyrrhizin induces CYP enzyme content, enhancing phase I and II metabolism of xenobiotics, dietary toxins, and carcinogens.
- Autophagy Induction: In hepatocellular carcinoma cells, glycyrrhizin promotes autophagy through inhibition of the STAT3/Survivin pathway.
Who May Benefit from IV Glycyrrhizin?
Based on the available clinical evidence, IV glycyrrhizin may be considered for:
- Patients with chronic hepatitis C who are non-responders to interferon-based therapy
- Patients with chronic liver disease requiring hepatoprotective support
- Patients with drug-induced liver injury
- Patients with non-alcoholic fatty liver disease (NAFLD)
- Patients with autoimmune hepatitis
- Patients with alcoholic liver disease
It is important to note that for hepatitis C, the benefits of glycyrrhizin are now considered minor compared to modern direct-acting antiviral agents, though glycyrrhizin may still serve an adjunctive hepatoprotective role.
Safety Profile and Side Effects
IV glycyrrhizin is generally well tolerated, but the major dose-limiting toxicity is a mineralocorticoid (aldosterone-like) effect known as pseudoaldosteronism. This occurs because glycyrrhizin's metabolite, glycyrrhetinic acid, inhibits the enzyme 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2) in the kidney, leading to increased cortisol activity at the mineralocorticoid receptor.
Potential side effects include:
- Fluid retention and edema
- Hypertension (reported in approximately 5–9% of patients)
- Hypokalemia (reported in approximately 3.6% of patients)
- Suppression of plasma renin and aldosterone
- Rare: arrhythmia and thrombophlebitis (associated with daily IV administration)
Monitoring of blood pressure, serum potassium, and fluid status is recommended during therapy. Potassium supplementation may be necessary, particularly with long-term use.
Dosing and Administration
In clinical trials, IV glycyrrhizin has been administered at dosages of 40–240 mg per session, typically 3 to 5 times per week. The most commonly studied regimen in the phase 3 trial used IV glycyrrhizin 3 or 5 times per week for 12 to 52 weeks. Long-term therapy (years to over a decade) has been used in Japan for hepatocarcinogenesis prevention.
Frequently Asked Questions (FAQ)
What is IV glycyrrhizin used for?
IV glycyrrhizin is primarily used as a hepatoprotective agent for chronic liver diseases, including chronic hepatitis B and C, drug-induced liver injury, alcoholic liver disease, non-alcoholic fatty liver disease, and autoimmune hepatitis. It has also been studied for its antiviral, anti-inflammatory, and anticancer properties.
How does IV glycyrrhizin differ from oral licorice supplements?
IV glycyrrhizin delivers the active compound directly into the bloodstream, bypassing gastrointestinal metabolism and providing higher, more predictable bioavailability. Oral licorice contains many other compounds and has variable absorption, making IV administration the preferred route for therapeutic use.
Can IV glycyrrhizin cure hepatitis C?
No. While IV glycyrrhizin reduces liver inflammation and ALT levels, it does not eliminate the hepatitis C virus (HCV RNA levels remain unchanged). Modern direct-acting antiviral drugs are far more effective for curing hepatitis C. However, glycyrrhizin may serve as an adjunctive hepatoprotective therapy.
Does IV glycyrrhizin prevent liver cancer?
Long-term studies suggest that IV glycyrrhizin significantly reduces the rate of hepatocellular carcinoma development in patients with chronic hepatitis C, with one large cohort study showing a hazard ratio of 0.49 for hepatocarcinogenesis. This benefit is thought to result from suppression of hepatic necroinflammation rather than direct antiviral activity.
What are the side effects of IV glycyrrhizin?
The main side effects are related to pseudoaldosteronism: fluid retention, hypertension, and hypokalemia. These occur because glycyrrhizin inhibits the enzyme 11β-HSD2 in the kidney. Regular monitoring of blood pressure and serum potassium is recommended.
How often is IV glycyrrhizin administered?
Clinical trials have used schedules of 3 to 5 times per week. Long-term maintenance therapy in Japan has been administered for years to decades in patients with chronic liver disease.
Is IV glycyrrhizin FDA-approved?
IV glycyrrhizin (as SNMC) is approved and widely used in Japan for chronic liver disease. It is not FDA-approved in the United States but has been studied in international clinical trials.
Can IV glycyrrhizin be used alongside other treatments?
Yes. Studies have evaluated glycyrrhizin in combination with ursodeoxycholic acid (UDCA), showing that combined therapy produced greater reductions in AST and ALT than glycyrrhizin alone. It has also been studied as an adjunct to interferon therapy.
Is IV glycyrrhizin safe for long-term use?
Long-term use (over 10 years) has been documented in Japanese studies with an acceptable safety profile, provided that blood pressure and potassium levels are monitored regularly. Potassium supplementation may be required due to the long half-life of glycyrrhetinic acid.
Does IV glycyrrhizin have antiviral activity beyond hepatitis?
Yes. In vitro and preclinical studies have demonstrated antiviral activity against influenza A, HIV, herpes simplex virus, SARS-CoV-2, respiratory syncytial virus, varicella zoster, and other viruses. Clinical evidence for these indications remains limited compared to hepatitis.