Formulation design of double-layer in the outer shell of dry-coated tablet to modulate lag time and time-controlled dissolution function: Studies on micronized ethylcellulose for dosage form design (VII)

Abstract

The dry-coated tablet with optimal lag time was designed to simulate the dosing time of drug administration according to the physiological needs. Different compositions of ethylcellulose (EC) powder with a coarse particle (167.5 µm) and several fine particles (<6 µm), respectively, were mixed to formulate the whole layer of the outer shell of dry-coated tablets. The formulations containing different weight ratios of coarse/fine particles of EC powders or 167.5 µm EC powder/excipient in the upper layer of the outer shell to influence the release behavior of sodium diclofenac from dry-coated tablet were also explored. The results indicate that sodium diclofenac released from all the dry-coated tablets exhibited an initial lag period, followed by a stage of rapid drug release. When the mixture of the coarse/fine particles of EC powders was incorporated into the whole layer, the lag time was almost the same. The outer shell broke into 2 halves to make a rapid drug release after the lag time, which belonged to the time-controlled disruption of release mechanism. When the lower layer in the outer shell was composed of 167.5 µm EC powder and the upper layer was formulated by mixing different weight ratios of 167.5 µm and 6 µm of EC powders, the drug release also exhibited a time-controlled disruption behavior. Its lag time might be freely modulated, depending on the amount of 6 µm EC powder added. Once different excipients were respectively incorporated into the upper layer of the outer shell, different release mechanisms were observed as follows: time-controlled explosion for Explotab, disruption for Avicel and spray-dried lactose, erosion for dibasic calcium phosphate anhydrate, and sigmoidal profile for hydroxypropyl methylcellulose.

Oral pulsatile delivery: Rationale and chronopharmaceutical formulations

“…Modifications of half of the coating formula were demonstrated to be a further means of modulating the lag phase. The obtained bipartite shells, however, possibly involved release mechanisms other than that observed when testing units coated with EC only (Lin et al, 2004b).…”

THE ROLE OF NEEDLE IN FORMULATION OF pH SENSITIVE SWELLABLE MICROBEADS PREPARED WITH HYDROPHILIC POLYMERS FOR ATORVASTATIN AND THEIR CHARACTERIZATION STUDIES

“…The higher mucoadhesion of carbopol 934P microspheres may also be attributed to the higher molecular weight of carbopol than HPMC [29]. These polymers are often used as a rate-controlling membrane to modulate the drug release from dosage forms with organic or aqueous coating techniques [30][31][32][33]. The principle of gelation or crosslinking of sodium alginate with aluminium chloride is based on the formation of a tight junction between the residues of guluronic acid.…”

Real-time in-die compaction monitoring of dry-coated tablets

“…The dry-coated tablet dosage form (i.e., the tablet-in-tablet design) is a time-and rate-controlled drug delivery device, which consists of a core tablet and an outer layer that is considerably thicker than typical tablet coats, and which completely surrounds the core (inner) tablet. Previous studies have reported that various drug release mechanisms have been realized by incorporating a range of excipients into the outer shell of the dry-coated tablet (Lin et al, 2004). The dry-coated tablet is typically manufactured utilizing a two-step compaction process where the inner core precedes the outer coating compaction in a specialized tablet press.…”