Mebeverine hydrochloride is supplied as a pharma-grade active pharmaceutical ingredient for immediate-release tablets, modified-release capsules, granulated oral preparations, and injectable formulations. The chemical substance is the hydrochloride salt of mebeverine, with molecular formula C₂₅H₃₅NO₅·HCl and molecular weight 466.0 g/mol. The compound is identified by CAS registry number 2753-45-9 and is controlled against the Ph. Eur. and BP monographs for mebeverine hydrochloride. Commercial release documentation normally includes HPLC assay, related substances, residual solvents, water content, sulfated ash, elemental impurities, particle-size distribution, and for injectable grades bacterial endotoxin. The material is produced as a white to almost white crystalline powder, and the hydrochloride salt is used because it provides sufficient aqueous solubility for both oral dissolution and injectable preparation while retaining the musculotropic action on gastrointestinal smooth muscle. The API is a single chemical entity, not a heterogeneous botanical extract, and should not be blended with other salt forms unless a full compatibility and bioequivalence evaluation has been performed.

Release Specification Architecture for Mebeverine Hydrochloride API

The pharmacopoeial specification structure is built around identification, purity, and physical state. Identification is performed by infrared absorption spectrophotometry (Ph. Eur. 2.2.24) against a reference standard, by liquid chromatography retention time (Ph. Eur. 2.2.29), and by a chloride reaction (Ph. Eur. 2.3.1) that confirms the salt form. The assay limit is normally 99.0–101.0% on the dried substance by HPLC, because the hydrochloride is a single chemical entity and the pharmacopoeial monograph does not allow a wide assay interval. Related substances are controlled by HPLC and in routine trade specifications total impurities are held at not more than 0.5% w/w, while the largest individual unknown impurity is commonly limited to not more than 0.10% w/w. Loss on drying by Ph. Eur. 2.2.32 is typically not more than 0.5% after drying at 105 °C to constant weight, and sulfated ash by Ph. Eur. 2.4.14 is not more than 0.1%. Residual solvents are reported according to Ph. Eur. 2.4.24 or USP <467> and must comply with ICH Q3C Option 1; elemental impurities are controlled under ICH Q3D and reported in the certificate of analysis. The certificate of analysis for each batch should also include water content by Ph. Eur. 2.5.12, because residual moisture directly affects flowability and compaction in high-speed tableting.

Solid-state characterization is usually performed by X-ray powder diffraction, differential scanning calorimetry, and dynamic vapour sorption. The material is a crystalline hydrochloride, and the X-ray powder diffraction pattern should match the reference batch or standard. The pharmacopoeial monograph does not require a melting range as a release criterion, so melting point alone is not used for identity; IR and HPLC retention time are the primary identification tests. Dynamic vapour sorption can be used to quantify moisture uptake, but routine release relies on water content by Ph. Eur. 2.5.12.

For direct compression of 135 mg immediate-release tablets, a direct-compression grade with a narrow particle-size distribution is used because the hydrochloride has high aqueous solubility and can segregate in hopper-fed tablet presses if the fines fraction is excessive. A common trade model is a white crystalline powder with D10 not more than 5 µm, D50 in the range 5–15 µm, and D90 not more than 20 µm by laser diffraction (Ph. Eur. 2.9.35). The powder is typically dry-blended with microcrystalline cellulose, lactose monohydrate, crospovidone, and magnesium stearate in a bin blender at 12–18 rpm for 15–20 minutes. In a 45-station rotary tablet press with round concave tooling, compression forces in the range 5–10 kN precompression and 15–25 kN main compression are often used, but machine-specific values must be established by factorial design because the material deforms plastically rather than by brittle fracture. Magnesium stearate is restricted to not more than 1.0% w/w and preferably added in a final external lubrication step to limit hydrophobic film formation that can reduce tablet hardness and slow dissolution. Published data for this exact formulation configuration is limited; therefore, laboratory-scale compaction simulation using a single-station instrumented press is recommended before pilot campaign.

The main processing conflict in direct compression arises when the API is milled to D90 below 20 µm to improve content uniformity. The micronized powder then exhibits lower bulk density and greater electrostatic charging, which can reduce flow through the forced feeder of a rotary tablet press. This is countered by adding 0.5–1.0% w/w colloidal silicon dioxide or by dry granulating the blend through roller compaction at a roll pressure of 30–60 bar and a roller speed of 5–10 rpm. Roller compaction is used when the direct compression blend has a Carr Index above 25% before lubrication; the compacts are milled through a 1.0 mm screen to create flowable granules. Batch-to-batch variance in particle size has been observed when the API mill feed rate exceeds 120 kg/h; therefore, the mill speed and classifier type should be locked in the manufacturing batch record.

Does Particle-Size Distribution Shift Wet Granulation End-Point for 200 mg Modified-Release Cores?

Granulated and capsule-based products tolerate a coarser API because the binder solution and subsequent drying create agglomerates that override the original API size. A high-shear granulator with impeller speed 300–500 rpm and chopper speed 1500–2000 rpm is typical; the wet mass is granulated until the end-point reaches a granule D50 of 150–250 µm by sieve analysis or Ph. Eur. 2.9.35. Loss on drying at the end of fluid-bed drying is often controlled at 1.5–2.5% w/w with inlet air temperature 55–65 °C. The final granules are milled through a 1.0 mm screen and filled into hard capsules. A wider API D90 of up to 180 µm can be used for wet granulation, but coarse fractions above 250 µm may survive milling and create content-uniformity failure in low-weight capsule fills. The distinction between direct-compression and wet-granulation grades is therefore not chemical but physical; both must meet the same assay and related-substance release limits.

Mixer torque rheometry can reduce batch-to-batch end-point variability. In a 75 L high-shear granulator, the torque rise from dry-mix baseline to wet mass endpoint is typically 2–3 N·m, but this value is formulation-specific and should not be transferred across equipment without a scale-up study. The granulation liquid is usually purified water or an aqueous binder solution; the water amount is commonly 35–45% w/w of the dry blend. Adding the binder too quickly can create large lumps that survive the 1.0 mm screen and cause capsule fill-weight variation.

Representative grade models for mebeverine hydrochloride API

Grade model	Intended process	D10	D50	D90	Additional release control
Direct compression	Immediate-release tablets	≤ 5 µm	5–15 µm	≤ 20 µm	Water ≤ 0.5%
Wet granulation	Tablets, granules, capsules	≤ 10 µm	40–80 µm	≤ 180 µm	Flowability index to be agreed
Injectable	Aseptic solution	≤ 2 µm	3–8 µm	≤ 15 µm	Endotoxin <0.10 EU/mg

When a manufacturer qualifies the API for injectable solutions, the specification must move beyond oral purity limits to include bacterial endotoxin, sub-visible particulate matter, and bioburden. An injectable-grade model is generally micronized to a D90 not more than 15 µm and controlled for endotoxin at less than 0.10 EU/mg by Ph. Eur. 2.6.14. Sub-visible particulate contamination of the finished injection is assessed by Ph. Eur. 2.9.19; the API itself is not a sterile product, so the finished sterile solution must be produced by terminal sterilisation or aseptic filtration. Aqueous solubility of the hydrochloride supports formulation in Water for Injection, but the compounding pH and dissolved-oxygen level should be controlled because the molecule may undergo hydrolytic or oxidative degradation under aggressive conditions. Terminal sterilisation at 121 °C for 15 minutes is not automatically acceptable for every formulation; assay loss, pH shift, and related substance profile should be verified. Published data on mebeverine hydrochloride injection stability under terminal sterilisation is limited, so aseptic filtration is often selected when the finished-product specification cannot tolerate hydrolysis.

For injectable manufacturing, the compounding vessel should be stainless steel or glass-lined, and the bulk solution should be filtered through a 0.22 µm membrane filter. Membrane compatibility must be checked because the hydrochloride can alter filter wettability. The dissolved oxygen level of the bulk solution should be maintained below 1.0 mg/L if oxidative degradation is observed during forced degradation; nitrogen blanketing is preferred in that case.

When Modified-Release Capsules Require Narrower Particle-Size Control Than Immediate-Release Tablets

Modified-release capsules and granules require a different particle-size and surface-area profile than immediate-release tablets because dissolution from coated multiparticulate systems is controlled by the film barrier, not by API solubility alone. In drug layering onto microcrystalline cellulose spheres, mebeverine hydrochloride is dispersed in an aqueous binder solution and sprayed in a bottom-spray fluid-bed coater; the API particles must be fine enough to remain suspended during spraying. A D90 below 30 µm is commonly required to prevent nozzle blockage and uneven drug layering. The coating step typically applies an ethylcellulose or polymethacrylate dispersion to a weight gain of 12–15% for sustained release, and the coating inlet temperature is held at 50–60 °C to avoid pellet agglomeration. The difference from the direct-compression product is not in chemical purity but in particle-size distribution and surface energy; micronization to an injectable-type PSD may create cohesion and poor flow if used in direct compression, while the direct-compression grade may settle in the spray suspension if used for drug layering.

For granule-based sachets, the API is often dry-mixed with sorbitol, mannitol, or sucrose and a flavouring agent before filling into stick packs. The granule blend should be sieved through a 1.0 mm screen and the final moisture held below 2.0% w/w to prevent caking. Because mebeverine hydrochloride is freely soluble in water, dissolution of the finished granule is usually rapid under gastric pH; however, dissolution testing should use the pharmacopoeial method for mebeverine hydrochloride tablets or a validated method for the oral granule. Published data for mebeverine hydrochloride oral granules is limited; therefore, dissolution acceptance criteria are typically derived from clinical batch data rather than compendial defaults.

Mebeverine HCl Compared with Hyoscine Butylbromide and Pinaverium Bromide

Mebeverine hydrochloride is selected over quaternary ammonium antispasmodics when a musculotropic agent is required without the antimuscarinic adverse effect profile of hyoscine butylbromide. Hyoscine butylbromide is a quaternary ammonium antimuscarinic with a different aqueous-solubility and permeability profile, and it is not equivalent to mebeverine hydrochloride at the molecular or formulation level. Pinaverium bromide is another gastrointestinal selective agent, but its bromide salt is practically insoluble in water and is therefore restricted to oral solid dosage forms. Mebeverine hydrochloride, by contrast, can be formulated as an oral solution or injectable solution after appropriate solvent and pH adjustment. The molecular weight of mebeverine hydrochloride is 466.0 g/mol, which influences dose-to-molar equivalence when comparing salt forms. Formulators should avoid substituting mebeverine embonate or other salts without a full bioavailability and dissolution comparison.

Comparative differentiation of mebeverine hydrochloride from other gastrointestinal antispasmodic APIs

Parameter	Mebeverine hydrochloride	Hyoscine butylbromide	Pinaverium bromide
Pharmacological class	Musculotropic smooth-muscle relaxant	Quaternary ammonium antimuscarinic	Calcium-channel blocking musculotropic agent
Aqueous solubility	Freely soluble as hydrochloride salt	Freely soluble	Practically insoluble in water
Injectable formulation feasibility	Yes, after aseptic processing	Yes, as solution	Not conventional due to solubility
Typical oral dose	135 mg three times daily	10–20 mg four times daily	50 mg three times daily
Main processing implication	Water-soluble salt; direct compression feasible with controlled PSD	Hygroscopic; low-dose content uniformity critical	Low solubility; micronization or solubilization needed

The API is packaged in double low-density polyethylene liners inside a fiber drum or triple-laminated aluminium pouch, with desiccant when the shipment crosses high-humidity zones. Storage conditions are generally controlled at 15–25 °C in a dry place. Long-term storage above 25 °C may increase agglomeration of micronized injectable grade. The material should not be exposed to open air at relative humidity above 60% for extended periods because the hydrochloride may absorb moisture, altering flow and assay weight correction. Because the hydrochloride is water-soluble, cleaning validation for multi-product tablet suites should include recovery studies from stainless steel and polymer contact surfaces using a validated HPLC method with a limit of detection below 0.1 µg/mL.