Bivslirudin Pharma Grade API for tablet, capsule, granule, and injection applications is a synthetic 20-amino-acid peptide direct thrombin inhibitor chemically identical to bivalirudin, CAS 128270-60-0, with molecular formula C₉₈H₁₃₈N₂₄O₃₃ and monoisotopic molecular mass 2180.29 g/mol. The peptide is a hirudin analogue in which an N-terminal D-Phe-Pro-Arg-Pro segment reversibly blocks the thrombin catalytic site and a C-terminal tail occupies thrombin exosite I. The API is supplied as a white to off-white lyophilized powder. Two end-use grades are specified: an injectable grade controlled for bacterial endotoxin and particulate matter, and an oral solid dosage development grade controlled for microbial enumeration and residual solvent profile. The injectable-grade product is used to compound parenteral anticoagulant formulations. Oral tablet, capsule, and granule presentations are not pharmacopoeial approved forms because native bivalirudin undergoes gastrointestinal proteolysis and has negligible oral permeability; published data for this specific oral configuration is limited.

Release specifications for the injectable grade are method-dependent. Table 1 summarizes a representative specification matrix aligned with pharmacopoeial testing chapters. The assay and related-substance acceptance criteria should be verified against the current USP bivalirudin monograph, ICH Q3A thresholds, and ICH Q3D elemental impurity limits.

Peptide purity is critical because bivalirudin contains Asn and Asp residues; deamidation, peptide bond hydrolysis, and aggregate formation are known degradation routes for this peptide class. The reversed-phase HPLC method used for assay and related substances should resolve deamidated and truncated fragments. Method validation for specificity, linearity, accuracy, and range follows ICH Q2(R1). The injectable grade includes a bacterial endotoxin limit of ≤ 0.5 EU/mg; the oral development grade may be released under USP <61>/<62> microbial enumeration without the same endotoxin limit, because the oral route does not impose a pyrogen threshold as stringent as parenteral administration.

Analytical control for oral and injectable grades differs by release tests, not by molecular identity. An injectable-grade API requires bacterial endotoxin and particulate control; an oral development grade may be released under microbial enumeration and residual solvent limits. In both cases, the HPLC assay must be stability-indicating and should separate deamidated and truncated fragments. This is a difference from small-molecule APIs, where a single HPLC impurity method is often sufficient.

Where Does Bivslirudin Fit Among Parenteral Direct Thrombin Inhibitors?

Bivslirudin differs from unfractionated heparin and low-molecular-weight heparin by direct reversible inhibition of thrombin without antithrombin III. It binds both thrombin exosite I and the catalytic site, whereas argatroban binds only the catalytic site. Bivalirudin does not bind to platelet factor 4 and is used in patients with heparin-induced thrombocytopenia requiring percutaneous coronary intervention. The molecular mass of 2180.29 g/mol is lower than unfractionated heparin’s polydisperse average of approximately 15,000 Da and higher than argatroban’s 508.6 g/mol. These physicochemical differences result in distinct clearance routes. Bivalirudin has an elimination half-life of approximately 25 min after intravenous administration in patients with normal renal function, with elimination by proteolytic cleavage and renal excretion. Argatroban is cleared by the hepatobiliary route and is used when severe renal impairment requires an alternative to bivalirudin. Unfractionated heparin has both reticuloendothelial and renal clearance; low-molecular-weight heparin relies more heavily on renal clearance.

In the approved injectable presentation, bivalirudin is supplied as a lyophilized vial containing 250 mg bivalirudin and 125 mg mannitol; reconstitution with 5 mL Water for Injection gives 50 mg/mL. The prescribing information provides dosing as an intravenous bolus of 0.75 mg/kg followed by an infusion of 1.75 mg/kg/h during percutaneous coronary intervention. In patients with creatinine clearance <30 mL/min, infusion rate reduction is required; published labeling gives the specific adjustment. Because no antidote exists, bleeding is managed by discontinuation and supportive measures.

Differences from other products also extend to reconstitution and administration. Bivalirudin is not compatible with heparin in the same intravenous line; argatroban and bivalirudin are both direct thrombin inhibitors but are not interchangeable because of differences in half-life, clearance route, and clinical monitoring. For formulation development, the large peptide mass of bivalirudin makes it more sensitive to pH, shear, and temperature than the small molecule argatroban.

For oral tablet and capsule development with Bivslirudin, the API is not directly compressible and cannot be considered bioequivalent to the injectable form merely by chemical assay. The peptide is freely water-soluble and highly charged; the molecular mass of 2180.29 g/mol exceeds the threshold for paracellular transport. Gastric pepsin and intestinal brush-border proteases cleave the peptide before absorption. Enteric coating of granules or tablets with a methacrylic acid-ethyl acrylate copolymer dispersion can protect against gastric acidity but does not prevent intestinal proteolysis or improve permeability. Protease inhibitors, tight-junction modulators, and lipid-based self-emulsifying systems have been investigated for peptide delivery, but published data for bivalirudin-specific oral bioavailability in humans is limited. An oral development batch therefore requires more than blend uniformity; it requires degradation products in simulated gastric and intestinal media, residual moisture after granulation, and dissolution testing using USP <711> apparatus with pH-shift media. Acceptance criteria for an oral bivalirudin product have no current pharmacopoeial monograph and would be development-specific.

Capsule / Granule Processing Constraints for a 2180 Da Peptide

Dry processing in a low-shear tumble blender is preferred over high-shear wet granulation because Bivslirudin hydrates into a tacky mass during aqueous granulation. If wet granulation is unavoidable, a fluid-bed granulator with inlet air temperature not exceeding 30 °C and product temperature maintained below 25 °C reduces aggregation and deamidation. Drying endpoint is confirmed by Karl Fischer titration, with residual moisture below 2.0% for encapsulated granule fills. Direct compression of the neat API is not practical; spray-dried or roller-compacted intermediates containing mannitol or trehalose as bulking agents are required. Roller compaction ribbons should be milled under controlled humidity, and compaction pressure should be minimized because excessive shear can produce amorphous content and reduce peptide stability. Packaging for oral development batches requires heat-sealed aluminum blisters with desiccant when ambient relative humidity exceeds 60%.

Process analytical technology using near-infrared reflectance spectroscopy can monitor blend uniformity of bivalirudin-mannitol blends. However, the peptide’s spectral overlap with mannitol requires careful chemometric model validation, and published data for this specific configuration is limited. In-process control for oral solid dosage development should include particle size distribution by laser diffraction, moisture by Karl Fischer, and blend uniformity by a validated HPLC method.

Manufacture of injectable dosage forms from Bivslirudin injectable-grade API uses aseptic processing in an ISO 14644-1 Class 5 environment. The API is dissolved in Water for Injection and filtered through a 0.22 µm sterilizing-grade filter; terminal moist-heat sterilization is avoided because autoclaving degrades the peptide. Batch-to-batch variance in residual trifluoroacetate or acetate influences the pH of the reconstituted solution. When reverse-phase HPLC purification uses trifluoroacetic acid-modified mobile phases, residual TFA must be reduced by ion exchange; otherwise the lyophilized cake may show pH drift after reconstitution. The filling line should use low-shear peristaltic pumps or ceramic rotary piston pumps to minimize peptide aggregation. Filter compatibility studies with product mass balance are required because peptide adsorption to membrane materials can reduce delivered dose.

Cleaning validation for shared manufacturing equipment should use swab and rinse sampling with HPLC detection; acceptance limits are based on health-based exposure limits and the carryover potential for a peptide of 2180.29 g/mol. Dedicated or disposable product-contact components are preferred where cross-contamination risk cannot be controlled by cleaning alone.

When Injectable-Grade Bivslirudin Is Used in Lyophilized Vial Filling

When the API is formulated as a lyophilized injection, the cycle design is governed by the glass transition temperature of the maximally concentrated frozen solution and the collapse temperature of the cake. Mannitol is commonly used as a bulking agent in bivalirudin injection; the freeze-dry cycle cannot be transferred directly from small-molecule products. Sublimation rate must be balanced to prevent microcollapse, which produces a high residual moisture cake with extended reconstitution time. Lyophilized vials are released for moisture content by Karl Fischer, typically ≤ 2.0%, and for visible particulates by USP <790>. Subvisible particulates in the reconstituted solution are measured by light obscuration according to USP <788>. The reconstituted product is diluted in 0.9% sodium chloride or 5% dextrose for intravenous administration. Separate infusion lines are required when heparin or thrombolytic agents are co-administered because of incompatibility; the prescribing information directs against mixing bivalirudin with other drugs. Published data for this specific bivalirudin configuration is limited, but the incompatibility constraint is derived from the approved labeling.