Compaction properties of composite particles consisting of lactose with sodium alginate prepared by spray-drying

Spray Drying for Direct Compression of Pharmaceuticals

Tableting by direct compression (DC) is one of the simplest and most cost-effective drug manufacturing approaches. However, most active pharmaceutical ingredients (APIs) and excipients lack the compression and flow properties required to meet the needs of high-speed industrial tablet presses. Therefore, the majority of DC APIs and excipients are modified via processing/co-processing particle engineering techniques to boost their properties. Spray drying is one of the most commonly employed techniques to prepare DC grades of APIs and excipients with prominent advantages. This review aims to present an overview of the commercially marketed and investigationally-prepared DC APIs and excipients produced by spray drying.

Tableting and tablet properties of alginates: characterisation and potential for Soft Tableting

The aim of the study was to evaluate the suitability of alginates for Soft Tableting. For this purpose the compaction properties of alginates, varying in molecular weight, guluronic acid/mannuronic acid ratio and salt, were investigated and compared to MCC. Based on the mechanical properties, the suitability of the tested excipients for Soft Tableting was predicted. In order to test the prediction the tested materials were used to tablet enteric coated pellets, which served as a pressure sensitive material. The tableting behaviour was analysed by the 3-D modeling technique. The tablet properties were analysed by determining the elastic recovery and the compactibility. Alginates in general deformed elastically. The compression behaviour depended on the chemical composition of the alginates with sodium alginates being more elastic than potassium alginates. Tablets containing alginates with low guluronic acid content exhibited higher elasticity than tablets with alginates having a low mannuronic acid content. The plasticity of potassium alginates was higher than for sodium alginates. However, the plasticity of all tested alginates was lower than the plasticity of MCC. The compactibility of the tested alginates was sufficient. The proposed prediction, which states that tableting excipients with higher elasticity are more suitable for tableting sensitive materials than plastic excipients, was valid for the tested materials. The elastic alginates inflicted less damage on the pellets than the plastic MCC. Thus, all alginates were more appropriate for tableting pressure sensitive materials than MCC.

Effect of Formulated Ingredients on Rapidly Disintegrating Oral Tablets Prepared by the Crystalline Transition Method

The aim of this article was to determine the optimal ingredients for the rapidly disintegrating oral tablets prepared by the crystalline transition method (CT method). The effect of ingredients (diluent, active drug substance and amorphous sugar) on the characteristics of the tablets was investigated. The ingredients were compressed and the resultant tablets were stored under various conditions. The oral disintegration time of the tablet significantly depended on diluents, due to differences in the penetration of a small amount of water in the mouth and the viscous area formed inside the tablet. The oral disintegration time was 10-30 s for tablets with a tensile strength of approximately 1 MPa, when erythritol, mannitol or xylitol was used as the diluent. The increase in the tensile strength of tablets containing highly water-soluble active drug substances during storage was as large as that of tablets without active drug substances, while the increase in the tensile strength of tablets containing low water-soluble active drug substances was small. It was therefore found that highly water-soluble active drug substances were more suitable for the formulation prepared by the CT method than low water-soluble active drug substances. Irrespective of the type of amorphous sugar (amorphous sucrose, lactose or maltose) used, the porosity of tablets with 1 MPa of tensile strength was 30-40%, and their oral disintegration time was 10-20 s. The optimal ingredients for rapidly disintegrating oral tablets with reasonable tensile strength and disintegration time were therefore determined from these results.

Hydrophilic excipients modulate the time lag of time-controlled disintegrating press-coated tablets

An oral press-coated tablet was developed by means of direct compression to achieve the time-controlled disintegrating or rupturing function with a distinct predetermined lag time. This press-coated tablet containing sodium diclofenac in the inner core was formulated with an outer shell by different weight ratios of hydrophobic polymer of micronized ethylcellulose (EC) powder and hydrophilic excipients such as spray-dried lactose (SDL) or hydroxypropyl methylcellulose (HPMC). The effect of the formulation of an outer shell comprising both hydrophobic polymer and hydrophilic excipients on the time lag of drug release was investigated. The release profile of the press-coated tablet exhibited a time period without drug release (time lag) followed by a rapid and complete release phase, in which the outer shell ruptured or broke into 2 halves. The lag phase was markedly dependent on the weight ratios of EC/SDL or EC/HPMC in the outer shell. Different time lags of the press-coated tablets from 1.0 to 16.3 hours could be modulated by changing the type and amount of the excipients. A semilogarithmic plot of the time lag of the tablet against the weight ratios of EC/SDL or EC/HPMC in the outer shell demonstrated a good linear relationship, with r = 0.976 and r = 0.982, respectively. The predetermined time lag prior to the drug release from a press-coated tablet prepared by using a micronized EC as a retarding coating shell can be adequately scheduled with the addition of hydrophilic excipients according to the time or site requirements.

Compression behaviour and tablet-forming ability of spray-dried amorphous composite particles

The aim of this study was to investigate the compression behaviour and tablet-forming ability of spray-dried amorphous two- and three-component composite particles. Particles of lactose alone, two-component particles of lactose and PVP, and three-component particles of lactose, PVP and a small amount of polysorbate 80 were prepared by spray-drying. Two qualities of PVP with different molecular weights were used for the preparation of both types of particles. The particles were characterised with respect to permeametry surface area, moisture content, particle and bulk density, glass transition and crystallisation temperature, and heat of crystallisation. The tablet tensile strength of the different particles formed at a series of applied pressures was determined and compression parameters were derived from the Heckel and Kawakita equations. The presence of PVP gave particles that were less prone to deform permanently during compression while the presence of surfactant gave particles that were less able to form tablets. In conclusion, the compression behaviour and tablet-forming ability of spray-dried amorphous lactose can be modulated by the addition of stabilising polymers or surfactants to the spray feed solution.

Temperature- and moisture-induced crystallization of amorphous lactose in composite particles with sodium alginate prepared by spray-drying

The purpose of this study was to investigate the temperature- and moisture-induced crystallization of amorphous lactose in the composite particles prepared by spray-drying an aqueous solution of crystalline lactose and sodium alginate. The temperature-induced crystallization of amorphous lactose in the composite particles was suppressed by increasing the amount of sodium alginate in the particles. The stabilizing effect of sodium alginate on amorphous lactose in the composite particles was greater than that in physical mixtures having the same formulating ratios. The improved stability of amorphous lactose in the composite particles was attributed to an increase in the glass transition temperature (Tg) of the mixture. Moisture-induced crystallization of amorphous lactose was also retarded by increasing the amount of sodium alginate in composite particles. Although the Tg of the mixture was reduced by increasing the water content of the particles, the values were higher than that of 100% amorphous lactose when particles of the same water content were compared. The change in the Tg of the composite particles with increasing water content was interpreted as involving three components of the Gordon-Taylor equation. In the amorphous lactose-sodium alginate systems, the Tg values of the composite particles containing sodium alginate were higher than the theoretical line predicted by two components of the Gordon-Taylor equation. These results suggested that there was a specific interaction between the sodium alginate and lactose molecules. This specific interaction was suggested by the fact that only very little amorphous lactose was measured in the spray-dried composite particles stored under humid conditions using differential scanning calorimetry. This molecular interaction may also be partly responsible for the suppression of both the temperature- and moisture-induced crystallization of amorphous lactose in the composite particles.

Spray-dried lactose composite particles containing an ion complex of alginate-chitosan for designing a dry-coated tablet having a time-controlled releasing function

PURPOSE

The properties of novel spray-dried lactose composite particles suitable for the coating filler of a dry-coated tablet having a long induction period in drug release were investigated.

METHODS

To prepare spray-dried composite particles containing alginate-chitosan complex (SD(L/AL-CS)), an aqueous solution of lactose and sodium alginate and the acetic acid solution of chitosan were concomitantly fed into the rotary atomizer of a spray-dryer. The formation of the alginate-chitosan complex was confirmed by measuring the weight of insoluble portion in the mixture of sodium alginate and chitosan solutions. The dissolution properties of the dry-coated tablet were measured with the JP specified paddle method.

RESULTS

The micromeritic properties of SD(L/AL-CS) were compared to those of the SD composite particles of lactose-sodium alginate, having a good compacting property. The drug release profiles of dry-coated tablet with SD(L/AL-CS) contained a long induction period followed by a rapid drug release phase in the artificial intestinal fluid. The induction period for drug release to occur was increased with an increase in the degree of deacetylation of chitosan and in the amount of chitosan in the formulation. The prolongation of induction period was attributed to the formation of an insoluble ion complex between sodium alginate and chitosan in the composite particles, which could form a rigid gel structure on the tablet surface.

CONCLUSIONS

A time-controlled release tablet was designed with the composite particles of lactose containing the alginate-chitosan ion complex. The induction period of the dry-coated tablet could be prolonged in order to deliver the drug to the colon by controlling the type and amount of chitosan formulated in the composite particles.