Occurrence of Capping Due to Insufficient Air Escape during Tablet Compression and a Method to Prevent It.

Tanino, Tadatsugu; Aoki, Yoshihiro; Furuya, Y; Sato, Kōji; Takeda, Toyohiko; Mizuta, Taiichi

doi:10.1248/cpb.43.1772

Cited by 28 publications

(9 citation statements)

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“…In the pharmaceutical industry, capping has been studied extensively, yet the underlying mechanism of failure remains unclear. Several authors have attributed capping to air entrainment in the powder during compression which leads to a pressure rise which exceeds the yield stress of the tablet causing rupture (Mann, 1987;Mann et al, 1981Mann et al, , 1982Mann et al, , 1983Tanino et al, 1995). This research has demonstrated that alterations to the tableting operation designed to prevent air from escaping during compression can cause capping.…”

Section: Introductionmentioning

confidence: 91%

A numerical investigation of air flow during tablet compression

Kremer

2006

Chemical Engineering Science

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Section: Introductionmentioning

confidence: 91%

A numerical investigation of air flow during tablet compression

Kremer

2006

Chemical Engineering Science

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“…with an increase in the stress relaxation parameter), strength of the interparticle bonding inside the compressed powder increased and the prepared tablet becomes more rigid. 12) Thus, a new interparticle bonding parameter E b (t) was proposed by taking into account the stress relaxation parameter. The E b (t) is …”

Section: Applicability Of the E E -E P Diagram To The Doublecompressimentioning

confidence: 99%

“…In manufacturing processes, most of the pharmaceutical tablets are produced by the double-compression, in which the powder is compressed twice. 12) Many previous works [12][13][14] reported that mechanism of the double-compression is significantly different from that of the single-compression due to relaxation of the stress accumulated inside the compressed powder. Therefore, applicability of the E e -E p diagram to evaluate the tablets prepared by the double-compression needs to be studied.…”

mentioning

confidence: 99%

In-Die Evaluation of Capping Tendency of Pharmaceutical Tablets Using Force-Displacement Curve and Stress Relaxation Parameter

Nakamura

Sugino

Watano

2012

CHEMICAL & PHARMACEUTICAL BULLETIN

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A novel in-die evaluation method of tablet capping tendency was proposed based on a force-displacement curve and stress relaxation parameter in a tableting process. In our previous study (Chem. Pharm. Bull., 59, 2011, Nakamura et al.), the phase diagram consisting of elastic recovery energy (E e ) and plastic deformation energy (E p ) of compressed powder, named as the E e -E p diagram, was proposed. However, it was found that capping tendency of tablets prepared by double-compression with multi-component powder formulations cannot be discriminated using the E e -E p diagram. To improve the capping discrimination ability, we here proposed a novel corrected phase diagram consisting of the E e and an interparticle bonding parameter E b (t), named as the E e -E b (t) diagram. The E b (t) was proposed as a new parameter expressing strength of the interparticle bonding formed by the stress relaxation inside compressed powder. The E b (t) was defined as a product of the E p and the stress relaxation parameter Y(t), estimated from the force-displacement curve and the stress relaxation test. The capping discrimination ability of the diagrams was evaluated using a hierarchical-clustering analysis. The results exhibited that the capping tendency could be clearly discriminated using the proposed E e -E b (t) diagram at the double-compression and the multi-component powder formulations, as compared to the E e -E p diagram. This proposed diagram can be used for screening of the powder formulations to avoid the capping.Key words tableting; capping; stress relaxation; force-displacement curve; hierarchical-clustering analysis When pharmaceutical powders are compressed into tablets, cracking or lamination sometimes occurs inside the tablets. This phenomenon is well known as capping. The capping is one of the most common tableting troubles. Although many efforts have been made to overcome the trouble, the capping has still been an unsolved issue. Thus, a methodology to evaluate and avoid the capping has been a strong interest in pharmaceutical industries.Generally, capping tendency can be evaluated by out-ofdie or in-die evaluation methods. In the out-of-die evaluation methods the capping tendency is evaluated after ejection of the tablet from a die, whereas in the in-die evaluation methods the capping tendency is evaluated during preparation of the tablet.As an out-of-die evaluation method of the capping tendency, visual inspection after a friability test 1) is widely accepted. An indentation fracture test 2) has been proposed as an out-of-die evaluation method, in which the capping tendency was evaluated by making a small indentation fracture on the tablet. An X-ray microtomography, 3,4) by which cracks inside a tablet can be directly visualized noninvasively, has also been employed as an out-of-die evaluation method. However, the out-of-die evaluation methods are cumbersome, because they need to handle tablets after their preparation.By contrast, in-die evaluation methods can evaluate the capping tendency using data monitored...

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“…Preventing capping during the entire tabletting process is highly desired because the capped tablets have a severe influence on the tablet quality during the subsequent coating, handling, packaging and transport processes. To prevent capping, many research studies have been conducted on the factors that cause capping, such as the local stress concentration due to elastic recovery (Dwivedi et al, 1992;Han et al, 2008), high residual die wall pressure (Sugimori et al, 1989a(Sugimori et al, , 1989b, air entrapment (Tanino et al, 1995), and weak binding strength between granules (Sugimori et al, 1989b). In general, the capping tendency is considered to decrease with reducing tabletting speed, adding pre-compression, applying low compaction forces, improving the formulation and optimising the blending process.…”

Section: Introductionmentioning

confidence: 99%