Ribavirin powder, also known as ribavirin nucleoside, 1- β - D-ribofuranosyl-1H-1,2,4-triazole-3-carboxamide, is a drug ingredient with antiviral activity. It is a white or off white crystalline powder, odorless, with a melting point of 174-176 ℃ and a boiling point of 639.8 ℃. It is easily soluble in water and slightly soluble in organic solvents such as ethanol, chloroform, and ether. At the same time, it is a broad-spectrum antiviral drug that mainly inhibits the synthesis and transcription enzymes at the 5 'end of viral mRNAs, thereby suppressing the synthesis of DNA and RNA and achieving antiviral effects. It is widely used for the prevention and treatment of diseases caused by various viruses such as influenza virus, herpes virus, poxvirus, adenovirus, and rotavirus. In the field of veterinary medicine, ribavirin is also commonly used as an antiviral raw material for the prevention and treatment of animal diseases.
Additional information of chemical compound:
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Chemical Formula |
C8H12N4O5 |
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Exact Mass |
244.08 |
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Molecular Weight |
244.21 |
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m/z |
244.08 (100.0%), 245.08 (8.7%), 245.08 (1.1%), 246.09 (1.0%) |
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Elemental Analysis |
C, 39.35; H, 4.95; N, 22.94; O, 32.76 |
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Melting point |
174-176℃ |
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Boiling point |
387.12℃ (rough estimate) |
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Density |
1.4287 (rough estimate) |
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Storage conditions |
2-8℃ |
Molecular structure and composition
The chemical name of ribavirin powder is 1 - β - D - furanose - 1H - 1,2,4 - triazole - 3 - formamide. Its molecular structure consists of a furanose ring, a triazole ring, and a formamide group. This unique structure endows it with specific chemical and biological activities. The furanose ring endows it with a certain degree of hydrophilicity, enabling it to interact with water molecules in the body, which is beneficial for the dissolution of the drug and its transportation within the body; the triazole ring and the formamide group are the key structural parts that enable it to exert its antiviral effect, participating in the interaction with virus-related targets.
Physical properties
Appearance: It is usually a white or off-white crystalline powder. This pure appearance is an external manifestation of its high purity. In the production and quality control of drugs, the appearance is one of the important indicators for initially judging the quality of the drug.
Solubility: It has certain solubility in water, which enables it to be conveniently formulated into various aqueous preparations, such as injections and oral solutions. At the same time, it is also soluble in organic solvents like dimethylformamide, and these organic solvents can be used to dissolve ribavirin during drug research and analysis, for various chemical and physical property determinations as well as structural analysis.
Melting point: Ribavirin has a certain melting point range. The melting point is the temperature at which a substance changes from a solid state to a liquid state and is an important physical constant of the substance. By precisely determining its melting point, the purity of the drug can be preliminarily judged. The higher the purity, the narrower the melting point range and the closer it is to the theoretical value. In drug production, controlling the melting point within an appropriate range is an important step to ensure the stability of the drug quality.
Chemical stability
Stability to light and heat
Ribavirin is relatively sensitive to light and heat. Under light conditions, especially under ultraviolet radiation, the drug molecules may undergo photochemical reactions, causing changes in the molecular structure and the formation of some inactive or toxic degradation products. For example, the triazole ring or furan ribose ring may undergo ring-opening, oxidation and other reactions, thereby reducing the antiviral activity of the drug. High-temperature environments will also accelerate the decomposition reaction of the drug, affecting its stability and efficacy.
Therefore, during the storage and transportation of drugs, it is necessary to adopt conditions of avoiding light and low temperature, such as storing the drugs in brown bottles and placing them in a cool and dry place to extend the shelf life of the drugs.
Stability to acids and bases
In different acid-base environments, the stability of ribavirin varies. In acidic conditions, the drug may undergo hydrolysis reactions, resulting in the destruction of the molecular structure. For example, the amide group may undergo hydrolysis in an acidic environment, generating corresponding carboxylic acids and amine compounds, thereby losing antiviral activity.
In alkaline conditions, the drug may also undergo some chemical reactions, such as the ring-opening of the furan ribose ring. Therefore, in the preparation of formulations, appropriate pH conditions need to be selected to ensure the stability of the drug. The pH value of oral formulations usually needs to be controlled within a certain range to avoid excessive influence of the acid-base environment on the drug in the gastrointestinal tract.
Chemical reactivity
Functional group reactions
The functional groups in the ribavirin molecule have certain chemical reactivity. For example, the amide group can participate in some nucleophilic substitution reactions, acylation reactions, etc. In drug research, these functional group reactions can be utilized to modify ribavirin and synthesize a series of derivatives with different antiviral activity and pharmacokinetic properties to search for more effective and safer drugs.
Reactions with metal ions
Ribavirin can form complexes with some metal ions. This reaction may affect the solubility, stability and biological activity of the drug. For example, complexes formed with calcium, magnesium and other metal ions may reduce the absorption of the drug in the gastrointestinal tract, thereby affecting the efficacy of the drug. Therefore, in the preparation and clinical use of formulations, attention should be paid to the interaction between the drug and metal ions to avoid affecting the therapeutic effect of the drug due to complexation reactions.
Core Mechanism of Action
Ribavirin powder, also known as tribavirin powder, is a synthetic broad-spectrum nucleoside antiviral active pharmaceutical ingredient (API). It appears as a white or off-white crystalline powder, odorless with a slightly bitter taste. It exhibits good water solubility, slight solubility in ethanol, and stable physicochemical properties, making it a core antiviral raw material for human clinical and veterinary applications. Unlike single-target antiviral agents, it broadly inhibits both DNA and RNA viruses.
After entering host cells, ribavirin is phosphorylated by cellular kinases into active metabolites: ribavirin monophosphate, ribavirin diphosphate and ribavirin triphosphate.
Ribavirin monophosphate strongly suppresses inosine monophosphate dehydrogenase (IMPDH), blocking the intracellular guanosine synthesis pathway and depleting cellular guanine nucleotide pools, thereby interfering with viral nucleic acid replication and transcription. Meanwhile, ribavirin triphosphate competitively binds viral RNA polymerase, halting elongation and assembly of viral genomes and blocking the formation and release of progeny virions to curb viral proliferation at the source.
Additionally, ribavirin modulates host immune function and mitigates inflammation storms triggered by viral infection, reducing tissue and cellular injury. This property underpins its utility against a wide spectrum of viral diseases. Compared with virus-specific antivirals, ribavirin shows low tendency to induce viral resistance, covers a broader viral spectrum, and supports highly diversified clinical applications.
Human Clinical Applications
Treatment of Respiratory Viral Infections
Respiratory viral infections constitute the primary clinical application of tribavirin powder. The API can be formulated into oral preparations, nebulized solutions, injections, topical sprays and other dosage forms to accommodate patients of different ages and disease severities.
Nebulized ribavirin is a first-line clinical therapy for respiratory syncytial virus (RSV) infection in children and adults.
For severe bronchiolitis and viral pneumonia, targeted respiratory delivery acts directly on virus-infected airway mucosa, rapidly suppressing viral replication, relieving wheezing, cough and pulmonary rales, and lowering the risk of respiratory failure in critically ill patients.
For influenza A and B, early ribavirin administration shortens the duration of fever, fatigue, myalgia and other symptoms, alleviating epithelial injury in the respiratory tract. It is especially suitable for mild and moderate cases during influenza epidemics as well as prophylactic intervention in high-risk populations.
The drug also delivers marked efficacy against adenovirus and parainfluenza virus-induced upper respiratory tract infections, viral pharyngitis and tonsillitis, effectively limiting viral spread and ameliorating respiratory inflammation.
Treatment of Systemic Viral Infections
Formulated tribavirin powder is widely and effectively used in managing systemic viral diseases. In hemorrhagic fever with renal syndrome, early ribavirin administration inhibits hantavirus replication, reduces systemic capillary damage, lowers incidence of severe complications such as shock and renal failure, and substantially improves patient survival; it serves as a foundational therapeutic agent for this condition.
In viral hepatitis, ribavirin is commonly combined with interferon for standardized treatment of chronic hepatitis C. The dual antiviral and immunomodulatory combination suppresses persistent HCV replication, reduces viral load, and delays progression of liver fibrosis and cirrhosis, forming an essential component of HCV combination regimens.
Ribavirin also acts as adjunctive therapy for herpesvirus diseases including measles, chickenpox and herpes zoster. It accelerates rash resolution, alleviates mucocutaneous inflammation and pain, and reduces transmission risk.
Adjunctive Therapy in Special Clinical Scenarios
Ribavirin powder delivers valuable adjunctive benefits in specific infectious conditions. For certain viral ocular diseases, ribavirin can be compounded into eye drops to treat adenoviral keratoconjunctivitis, inhibiting viral propagation on ocular mucosa and relieving dryness, redness and excessive secretions.
In clinical management of hand-foot-and-mouth disease, oral or intravenous ribavirin may be used for severe enterovirus infections to assist viral suppression, control systemic manifestations and reduce risks of disability and mortality from severe cases.
For coronavirus disease, ribavirin can serve as an adjunct antiviral agent combined with other antivirals in moderate and severe patients to help suppress viral replication and mitigate pulmonary inflammation, supporting clinical management. Strict adherence to physician guidance is mandatory.
Veterinary and Aquaculture Applications
Prevention and Treatment of Viral Diseases in Livestock and Poultry
Tribavirin powder is a widely used broad-spectrum antiviral API in livestock and poultry farming, offering favorable cost performance and versatile applicability against major viral diseases.
In poultry production, it prevents and treats prevalent viral diseases including Newcastle disease, avian influenza, infectious bronchitis and infectious bursal disease. Administered via feed or drinking water, it suppresses viral replication in poultry, reduces morbidity and mortality, and minimizes farming losses.
For livestock, ribavirin formulations alleviate fever, diarrhea and lethargy caused by porcine circovirus disease, porcine epidemic diarrhea, pseudorabies, bovine viral diarrhea and other disorders. It interrupts within-herd viral transmission and improves survival rates. The drug is also applied in aquaculture to control viral hemorrhagic disease, herpesvirus infections and other aquatic pathogens, meeting biosecurity demands in large-scale farming systems.
Advantages and Regulatory Compliance in Farm Biosecurity
Compared with alternative veterinary antivirals, tribavirin powder features broad-spectrum activity, rapid onset, low cost and convenient administration, fitting both large-scale and small-to-medium production systems.
Its powder form allows homogeneous mixing into feed or dissolution in water, supporting mass prophylaxis and collective treatment during outbreaks and greatly improving disease control efficiency.
Nevertheless, strict dosing and treatment duration protocols must be followed in farm use. Long-term or over-administration may cause adverse effects including immunosuppression and hematopoietic damage in animals. Operators must comply rigorously with prescribed withdrawal periods to prevent excessive drug residues and safeguard safety of animal-derived food products. Ribavirin has become an indispensable foundational agent within integrated viral disease prevention programs for livestock and poultry.
Classification of Mainstream Manufacturing Routes
Chemical Synthesis
Chemical synthesis represents the traditional industrial production route for ribavirin powder. It is technically mature, compatible with standard equipment and suitable for large-scale manufacturing. Key starting materials include inosine, guanosine and methyl 1,2,4-triazole-3-carboxylate. The full process involves multiple organic reaction steps followed by purification to obtain the final crystalline product.
The workflow consists of four core stages: acylation, condensation, aminolysis and refining. First, inosine reacts with glacial acetic acid and acetic anhydride under controlled temperature and catalysis in an acylation step that protects ribosyl hydroxyl groups, generating tetraacetylribose intermediate. This improves purity and conversion in subsequent condensation.
Purified tetraacetylribose is then combined with activated carbon-decolorized methyl 1,2,4-triazole-3-carboxylate. An acid-catalyzed condensation reaction produces a ribavirin precursor adduct. Acetyl protecting groups are removed via aminolysis to yield crude ribavirin.
Final refining includes dissolution, decolorization, recrystallization, centrifugal drying and multi-stage impurity removal to eliminate byproducts, residual catalysts and contaminants, yielding pharmacopoeia-compliant ribavirin crystalline powder. This route has low technical barriers and stable output yet suffers from lengthy sequences, high organic solvent consumption, substantial byproduct formation and relatively high environmental treatment costs.
Biocatalytic Enzymatic Synthesis
Biocatalytic enzymatic synthesis is an emerging green industrial process. With superior conversion rates, lower pollution and higher product purity, it is progressively replacing conventional chemical routes and becoming the dominant advanced production technology.
The process employs genetically engineered strain BL21/pET-His-pupG for fermentation. Controlled-temperature cultivation in fermenters amplifies biomass and yields highly active purine nucleoside phosphorylase (PNPase). Recombinant whole cells are immobilized using gelatin embedding to form a stable biocatalyst.
Using guanosine or inosine as substrates, the transglycosylation reaction proceeds for 12–20 hours in neutral buffer at 50–60°C. Enzymatic specificity directs selective linkage between the nucleoside and triazole moiety, generating crude ribavirin conversion liquor.
Cells and solid impurities are removed by centrifugation and filtration, producing clear supernatant. Ultrafiltration purification, concentration, recrystallization and vacuum drying yield high-purity tribavirin powder. This route exhibits exceptional reaction specificity with conversion above 95%, drastically reducing byproducts and organic solvent demand.
Mild reaction conditions lower energy consumption, aligning with green pharmaceutical standards. The finished drug delivers higher purity, fewer impurities and improved pharmaceutical safety, making it the primary production pathway for premium pharmaceutical-grade tribavirin powder.
Frequently Asked Questions
What is ribavirin powder for solution?
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Virazole (ribavirin for inhalation solution, USP) is indicated for the treatment of hospitalized infants and young children with severe lower respiratory tract infections due to RSV.
Does ribavirin dissolve in water?
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Ribavirin is a white, crystalline powder. It is freely soluble in water and slightly soluble in anhydrous alcohol.
What is the main use of ribavirin?
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RIBAVIRIN (rye ba VYE rin) treats infections caused by the hepatitis C virus. It works by limiting the spread of the virus inside the body. This medication does not kill the virus and it may still be possible to spread the virus to others. It will not treat colds, the flu, or infections caused by bacteria.
How long is ribavirin treatment?
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Adult Patients.
The recommended dose of ribavirin tablets is provided in Table 1. The recommended duration of treatment for patients previously untreated with ribavirin and interferon is 24 to 48 weeks. The daily dose of ribavirin is 800 mg to 1200 mg administered orally in two divided doses.
How to compound ganciclovir?
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The contents of the vial should be prepared for administration in the following manner: Reconstitution Instructions: Reconstitute lyophilized ganciclovir for injection by injecting 10 mL of Sterile Water for Injection, USP, into the vial.
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