Film-Coated Immediate-Release Tablet Manufacture

Cetirizine dihydrochloride is incorporated at 10 mg per unit in film-coated immediate-release tablets, corresponding to 4.0% w/w to 8.0% w/w of the core mass when total core weight is between 125 mg and 250 mg. The compendial control framework for this dosage form requires USP <905> uniformity of dosage units with an acceptance value of L1 = 15 for 10 mg single-dose units, USP <711> dissolution testing using the apparatus specified in the cetirizine hydrochloride tablet monograph, Ph. Eur. 2.9.40 uniformity of dosage units, and Ph. Eur. 2.9.3 dissolution. Elemental impurity risk assessment is conducted per ICH Q3D, with routine release verifying that Class 1 elements do not exceed 30% of the permitted daily exposure. The direct-compression process begins with a staged geometric pre-blend of cetirizine dihydrochloride with lactose monohydrate or microcrystalline cellulose in a bin blender at rotation speeds from 10 rpm to 20 rpm, followed by addition of sodium starch glycolate at 2.0% w/w to 4.0% w/w and magnesium stearate at 0.5% w/w to 1.0% w/w; magnesium stearate is added in a final lubrication step not exceeding 5 min to avoid over-lubrication and dissolution retardation. Tablet compression on a rotary tablet press with force feeder uses pre-compression force 2 kN to 4 kN and main compression force 8 kN to 18 kN, with weight variation controlled to ±5.0% for individual units. Film coating with hydroxypropyl methylcellulose/hypromellose is applied in a perforated pan at 2.0% w/w to 4.0% weight gain, with inlet air temperature 60 °C to 75 °C and atomizing air pressure 1 bar to 2 bar, to mask bitterness and improve swallowability. The terminal product is a scored or unscored 10 mg film-coated immediate-release tablet for allergic rhinitis, chronic idiopathic urticaria, and other histamine-mediated conditions.

Production-scale experience with direct compression of cetirizine hydrochloride has demonstrated that blend uniformity failures on high-speed presses are most frequently associated with API particle size distribution and hopper segregation rather than with diluent flow. When the API has a D90 above 100 µm, low-dose pockets can form in the feed frame dead zones, causing superpotent or subpotent tablets; the corrective action is a pre-blend with a fine-milled lactose fraction or a dry granulation roll-compaction step. Dissolution failure is most often traced to over-lubrication when magnesium stearate is mixed for more than 5 min or when total lubricant exceeds 1.0% w/w, producing a hydrophobic film that delays wetting. In that case, USP <711> dissolution at the first time point can fall below specified limits while content uniformity remains acceptable. The process boundary therefore requires that magnesium stearate be screened and added last, that blender fill volume be maintained between 50% and 70% of shell capacity, and that relative humidity during compression be held below 50% RH to prevent tablet capping and picking due to moisture uptake by the API. If the facility cannot maintain 50% RH, pre-drying of the blend at 40 °C for 2 h may be required, but this step must be followed by moisture content determination before compression because overdried blends can increase electrostatic adhesion of API to metal surfaces. The film-coated tablet route remains the most extensively documented downstream use of cetirizine hydrochloride, with product-specific monographs and a well-defined dissolution acceptance procedure.

Low-dose cetirizine hydrochloride powder blends intended for hard gelatin or hypromellose capsule filling require segregation risk control before encapsulation. The API content is 10 mg per capsule; for a fill mass of 120 mg to 160 mg, the API loading is 6.3% w/w to 8.3% w/w. Industry compliance for this presentation is governed by USP <905> uniformity of dosage units, USP <711> dissolution for the finished capsule, and Ph. Eur. 2.9.40 for dosage unit uniformity; if the capsule is intended for pediatric dosing, the manufacturing site also follows ICH Q3D elemental impurity controls and 21 CFR 211.110 sampling requirements for in-process blend uniformity. The downstream operation is a dry blending and encapsulation process: cetirizine dihydrochloride is first pre-blended with a fine-milled lactose monohydrate or pregelatinized starch via geometric dilution, then screened through a 0.5 mm mesh, then blended in a bin or tumble blender with colloidal silicon dioxide at 0.2% w/w to 0.5% w/w and magnesium stearate at 0.5% w/w to 1.0% w/w. The lubricated blend is encapsulated on a dosator or tamping-pin machine at 20,000 capsules/h to 100,000 capsules/h depending on equipment; weight variation is monitored at ±5.0%, and fill depth is adjusted for blend bulk density to prevent underfilled or overfilled units. The primary process conflict is low-dose segregation: because cetirizine hydrochloride has a different particle size and bulk density than most direct-compression diluents, long transfer distances, pneumatic conveying, or hopper level fluctuations can increase content non-uniformity above the acceptance value. If dry blending cannot achieve sustained RSD below 5.0%, the formulation is switched to a dry granulation roll-compaction step or wet granulation, which densifies the API within excipient granules and improves downstream flow. The terminal product is a 10 mg hard gelatin or hypromellose capsule for oral administration, typically imprinted with product-specific identification; the capsule shell reduces the taste and swallowability complaints associated with immediate-release tablets in adult and adolescent patients.

The operational boundary for capsule filling is moisture-related: hard gelatin shells become brittle below 40% RH and tacky above 60% RH, so filling suites are controlled to 45% RH to 55% RH. Cetirizine hydrochloride is less hygroscopic than some antihistamines, but the blend still requires protection from humidity excursions; capsule storage is specified at 25 °C with excursions permitted no higher than 30 °C if stability data support. Incompatibility with amine-based fillers is not relevant to this formulation, but the use of reactive aldehyde-containing film-coating or capsule shell materials should be avoided in packaging because Schiff base formation can occur with primary amine groups at elevated temperature.

When Cetirizine Hydrochloride is Processed as Direct-Compression Granules

When cetirizine hydrochloride is instead produced as single-dose granules for oral suspension, the formulation is a 10 mg dose per sachet; for a 1 g fill, the API loading is 1.0% w/w, though the ratio may rise to 2.0% w/w in 500 mg pediatric sachets. Compliance for granule presentations uses USP <905> for uniformity of dosage units when packaged as measured-dose sachets, USP <711> dissolution after reconstitution or dispersion, and Ph. Eur. 2.9.12 sieve analysis for particle size distribution where the dosage form is a granule rather than a tablet or capsule. The manufacturing process typically involves a high-shear granulation or fluid-bed granulation step, not direct compression; cetirizine dihydrochloride is first dissolved or suspended in a binder solution of hydroxypropyl methylcellulose or povidone, then sprayed onto a mannitol, lactose, or sucrose-based carrier in a fluid-bed dryer at inlet temperatures from 50 °C to 70 °C. The granules are dried to a loss-on-drying of 1.0% to 2.5%, sieved to a particle size range of 0.5 mm to 1.0 mm, and blended with flow aids such as colloidal silicon dioxide at 0.2% w/w to 0.5% w/w before filling into stick-packs or sachets. Terminal packaging requires a moisture barrier, because granule caking occurs at relative humidity above 60%; desiccant pouches are typically inserted into bulk containers. The finished product is a 10 mg single-dose granule for oral suspension, intended to be dispersed in water or sprinkled onto soft food for pediatric and adult patients who cannot swallow solid units. Published data for the high-shear granulation route in this specific formulation is more limited than for tablet and capsule lines, so process parameters such as impeller speed and spray rate are established through design-of-experiments batches rather than taken from a fixed compendial standard.

Orally Disintegrating Tablet Matrix: Moisture Uptake and Friability Control

Orally disintegrating tablets based on cetirizine hydrochloride 10 mg are formulated to disintegrate in the oral cavity within 30 s without water; the API loading is typically 2.0% w/w to 5.0% w/w because the matrix is dominated by mannitol, microcrystalline cellulose, and a superdisintegrant. The compliance framework includes USP <701> disintegration with a 30 s limit where specified in the ODT monograph, USP <905> uniformity of dosage units, Ph. Eur. 2.9.1 disintegration for tablets and capsules, and the FDA CDER guidance on orally disintegrating tablets for size, weight, and internal dispersion requirements; dissolution testing uses USP <711> with medium appropriate for cetirizine hydrochloride. The production route is either lyophilization from an aqueous suspension or direct compression at low force. In direct compression, the blend contains granulated mannitol, crospovidone at 3.0% w/w to 5.0% w/w, and magnesium stearate at 0.5% w/w to 0.8% w/w; the compression force is intentionally low, on the order of 5 kN to 10 kN, to preserve porosity for rapid disintegration. Low compression force increases friability, so the core is usually not exposed; packaging in moisture-proof blisters with a desiccant is required because humidity above 40% RH causes mannitol-based matrices to soften and lose disintegration speed. Experience on production-scale rotary presses has shown that ODT formulations are sensitive to punch sticking caused by the hygroscopic API and by low compaction forces; the use of external lubrication systems or reduced turret speed can prevent tooling build-up. The terminal product is a 10 mg orally disintegrating tablet for patients who avoid swallowing solid doses, with the same systemic indications as conventional immediate-release tablets.

Injectable Cetirizine Hydrochloride: Terminal Sterilization and Subvisible Particulate Burden

Intravenous cetirizine hydrochloride is prepared as a sterile, preservative-free solution at a concentration of 10 mg cetirizine per 1 mL, equivalent to 1.0% w/v of cetirizine dihydrochloride; the drug substance is dissolved in water for injection with sodium chloride as tonicity-adjusting agent, and the pH is adjusted with hydrochloric acid or sodium hydroxide to 4.0 to 6.0. The injectable route is indicated for acute urticaria when oral administration is not feasible, and the product is packaged as a 2 mL single-dose vial. Compliance is anchored to USP <1> injections, USP <788> particulate matter in injections with a limit of 10 particles ≥10 µm and 2 particles ≥25 µm per container, USP <790> visible particulates, USP <785> osmolality, and USP <1207> container closure integrity. Sterility assurance follows USP <71> and process simulation requirements under 21 CFR 211.113; bacterial endotoxin limits are set at 0.5 EU/mg or less according to the monograph. The manufacturing process uses aseptic processing with 0.22 µm filtration; terminal steam sterilization at 121 °C for 15 min may be applied if stability data confirm no degradation, and the cycle is qualified with biological indicators of Geobacillus stearothermophilus at a 10⁻⁶ sterility assurance level. Filling is done on a peristaltic or rotary piston vial line under restricted-access barrier or isolator conditions, with nitrogen sparging if oxygen-sensitive degradation products are monitored. Subvisible particulate burden is the critical process risk: because the product is a low-viscosity aqueous solution, silicon dioxide fibers from glass vials, rubber stopper fragments, and insoluble metal particles from filling needles can pass undetected if the USP <788> test is not performed on retained samples after terminal sterilization. In-process checks include pH, clarity, fill volume, and osmolality; stability studies monitor related substances and particulate counts at 25 °C and 40 °C. The terminal product is a sterile 10 mg/mL intravenous injection, usually administered as a 10 mg dose over 1 to 2 min, with no preservative because single-dose vials obviate antimicrobial requirements under USP <51>.

Production-scale experience with terminal sterilization of cetirizine injection has shown that subvisible particle counts can increase after steam sterilization if the vial neck geometry and stopper coating are not optimized for high-temperature exposure; silicone dioxide from the stopper and glass delamination are the two most common sources of elevated USP <788> counts. Container closure integrity testing per USP <1207> is therefore performed after sterilization rather than only after filling, and the stopper is specified with a fluoropolymer-coated contact surface to minimize leaching. The operating boundary for dissolved oxygen is set at 2 ppm or lower, and headspace oxygen is maintained below 5% v/v if the solution is sensitive to oxidative degradation; otherwise, the formulation may remain stable for at least 24 months at 25 °C but the claim must be supported by ICH Q1A stability data. Unlike oral solid forms, the injectable route adds the obligation to control extractables and leachables per ICH Q3D and USP <1664>; glass type I borosilicate vials and chlorobutyl rubber stoppers are the standard materials, and extractable profiles are evaluated using HPLC-MS with volatile and semi-volatile organic compound screening. Published data for continuous manufacturing of cetirizine injection is limited, so batch production with in-process bioburden monitoring before filtration remains the regulatory expectation.

Oral liquid presentations of cetirizine hydrochloride at 1 mg/mL and 10 mg/mL are compounded as clear aqueous solutions with a pH adjusted to 4.0 to 5.5 because the drug is freely soluble in water and chemically stable at mildly acidic pH. The lower concentration is used for oral solution dosing in children; the higher concentration is used for oral drops. Compliance for this route includes USP <1111> microbiological examination of nonsterile products, with total aerobic microbial count not exceeding 10² CFU/mL and total combined yeast and mold count not exceeding 10¹ CFU/mL, and Ph. Eur. 5.1.4 for the microbiological quality of oral liquids; the drug product must also meet USP <911> viscosity if the formulation is thickened, and USP <791> pH where applicable. The formula contains cetirizine hydrochloride at 0.1% w/v to 1.0% w/v, sorbitol or glycerin as sweetening and viscosity-modifying agents, sodium acetate as buffering agent, and a preservative system such as methylparaben at 0.08% w/v to 0.18% w/v with propylparaben at 0.01% w/v to 0.02% w/v when multidose bottles are packaged; if a single-dose oral ampoule is used, the preservative can be omitted. The downstream process is liquid compounding in a jacketed stainless steel tank at 20 °C to 25 °C, with high-shear mixing at 500 rpm to 1,500 rpm until dissolution is complete, followed by filtration through 0.45 µm filter to remove undissolved particulate, then filling into amber glass or polyethylene terephthalate bottles with dropper or syringe adapters. The critical process control is preservative concentration after filtration because membrane adsorption can lower paraben levels below effective antimicrobial range; the site should assay preservatives in the filtered bulk solution before filling. The terminal products are oral solution at 1 mg/mL for pediatric use and oral drops at 10 mg/mL for adult or adolescent dosing; both are intended for accurate dose titration in patients who cannot swallow solid oral forms.