High Purity L-Cysteine Monohydrochloride Amino Acid Raw Material

Solubility & pH

• Highly soluble in water; soluble in dilute mineral acids; slightly soluble in ethanol; insoluble in ether, acetone and chloroform
• Aqueous solution is acidic; 10% aqueous solution pH ranges from 1.0 to 2.5
• Contains free thiol (-SH) functional group with strong reducing capacity, easily oxidized to L-cystine under air and alkaline environment

As a raw material for finished pharmaceuticals, Vidarabine is historically recognized for its activity against:

• DNA Viruses: Herpes simplex virus types 1 and 2 (HSV-1, HSV-2), Varicella-zoster virus (VZV), and Cytomegalovirus (CMV).

• Clinical Use: Prior to the widespread use of Acyclovir, Vidarabine was a first-line therapy for severe Herpes simplex encephalitis and neonatal herpes. Today, its primary topical application is in the treatment of acute keratoconjunctivitis and recurrent epithelial keratitis caused by HSV. It is also used systemically (intravenous infusion) in some regions for immunocompromised patients with VZV infections.

Vidarabine is classified as a potential reproductive hazard and an irritant. Safety Data Sheets (SDS) mandate the following:

• Hazard Statements (H360): May damage fertility or the unborn child (Category 1B).

• Precautionary Measures: Use fume hoods and wear impermeable gloves (e.g., nitrile), lab coats, and safety goggles. Avoid generating airborne dust.

• First Aid: In case of skin contact, wash immediately with copious soap and water. If inhaled, move to fresh air.

• Storage: Store in tightly sealed, light-resistant containers at 2°C to 8°C (refrigerated) for long-term stability. Avoid freezing.

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While superseded by newer nucleoside analogs (Acyclovir, Ganciclovir) for systemic use due to better bioavailability and lower toxicity, Vidarabine retains niche value. Its primary current application is ophthalmic ointment (3%) . Pharmacokinetically, the raw material has poor oral bioavailability (<10%) and is rapidly deaminated in the gastrointestinal tract, necessitating parenteral or topical administration.

Vidarabine API is a well-characterized, stable crystalline nucleoside analog. While its systemic use has declined, it remains a critical raw material for topical antiviral ophthalmic preparations, particularly where resistance to other agents occurs. Manufacturers must strictly control impurities (especially Ara-Hx) and water content to ensure final drug product efficacy.