Hydroxypropyl Starch

Category

Tablet and Capsule Diluent; Tablet and Capsule Disintegrant; Tablet Binder

Molecular Formula

(C6H10O5)n where n = 300-1000.

Grade

Pharmceutical Excipients

Description

Pregelatinized starch occurs as a moderately coarse to fine, white to off-white colored powder. It is odorless and has a slight characteristic taste. Examination of fully pregelatinized starch as a slurry in cold water, under a polarizing microscope, reveals no significant ungelatinized granules, i.e. no‘maltese crosses’characteristic of the starch birefringence pattern. Examination of samples suspended in glycerin shows characteristic forms depending upon the method of drying used during manufacture: either irregular chunks from drum drying or thin plates. Partially pregelatinized starch (e.g.Starch 1500G and Sepistab ST200) show retention of birefringence patterns typical of unmodified starch granules.

UNII

NA

Chemical Name

Pregelatinized starch

CAS Number

113894-92-1

Synonyms

Amylum pregelificatum; compressible starch; C*PharmGel; Instastarch; Lycatab C; Lycatab PGS; Merigel; National 78-1551; Pharma-Gel; Prejel; Sepistab ST200; Spress B820; Starch 1500 G; Tablitz; Unipure LD; Unipure WG220

Administration route

Oral, optical, vaginal

Dosage Form

Oral capsules, suspensions, and tablets; vaginal preparations

Stability and Storage Conditions

Pregelatinized starch is a stable but hygroscopic material, which should be stored in a well-closed container in a cool, dry place.

Source and Preparation

Food-grade pregelatinized starches are prepared by heating an aqueous slurry containing up to 42% w/w of starch at 62-72℃.Chemical additives that may be included in the slurry are gelatinization aids (salts or bases) and surfactants, added to control rehydration or minimize stickiness during drying. After heating, the slurry may be spray-dried, roll-dried, extruded, or drum-dried. In the last case, the dried material may be processed to produce a desired particle size range. Pharmaceutical grades of fully pregelatinized starch use no additives and are prepared by spreading an aqueous suspension of ungelatinized starch on hot drums where gelatinization and subsequent drying take place. Partially pregelatinized starch is produced by subjecting moistened starch to mechanical pressure. The resultant material is ground and the moisture content is adjusted to specifications.

Applications

Partially pregelatinized starch is a modified starch used in oral capsule and tablet formulations as a binder, diluent, and disintegrant.In comparison to starch, partially pregelatinized starch may be produced with enhanced flow and compression characteristics such that the pregelatinized material may be used as a tablet binder in dry-compression or direct compression processes.In such processes, pregelatinized starch is self-lubricating. However, when it is used with other excipients it may be necessary to add a lubricant to a formulation. Although magnesium stearate 0.25% w/w is commonly used for this purpose, concentrations greater than this may have adverse effects on tablet strength and dissolution. Therefore, stearic acid is generally the preferred lubricant with pregelatinized starch.Partially pregelatinized starch is used in oral dry powder hard capsule formulations. Both partially and fully pregelatinized starch may also be used in wet granulation processes.Fully pregelatinized starches can be used to make soft capsules, shells, and coatings as well as binders in tablets.

Safety

Pregelatinized starch and starch are widely used in oral solid-dosage formulations. Pregelatinized starch is generally regarded as a nontoxic and nonirritant excipient. However, oral consumption of large amounts of pregelatinized starch may be harmful. See Starch for further information.