US2638686A

US2638686A - Drying gelatin capsules

Info

Publication number: US2638686A
Application number: US196746A
Authority: US
Inventors: Stirn Frank Edwin; Taylor Arthur Sinclair
Original assignee: American Cyanamid Co
Current assignee: Wyeth Holdings LLC
Priority date: 1950-11-21
Filing date: 1950-11-21
Publication date: 1953-05-19
Anticipated expiration: 1970-05-19

Description

May 19, 1953 F. E. s'rlRN ErAL 2,638,686

DRYING GELATIN CAPSULES Filed Nov. 21, 195o ATTORNEY Patented May 19, 1953 DRYING'GELATIN CAPSULES vFrank Edwin Stirn, Evans Park, Pearl River, and Arthur Sinclair Taylor, isprlngfvalley, N. Y., assignors to American Cyanamid (lompany, New York, N. Y., a corporation of Maine Application November 21, 1950, Serial No. 196,746

7 Claims.

1 i This invention has for its object-a method for the drying of soft gelatin capsules in a particularly expeditious and economical manner and,at the same time provides a method of insuringthat they are evenly formed and fault-free.

-ln the past, gelatin capsules of `these-called soft variety have `been made by symmetrically assembling two mold shells together, at the same time nlling themwith a liquid, pressing them firmly together with cutting-out rims to cut the gelatin sheets and simultaneously unite to form-a homogeneous, symmetrical, liquid-filled soft gelatin capsule. These capsules `were placed `on trays `in a single layer and `permitted to air-dry, after which they were packed in vials, `bottles, or otherwise counted, sorted, inspected, shipped-or disposed of. i

This entails theiuse of many individual trays, which trays of course were 'very-convenient for the inspection, counting, sorting and processing of small numbers of individual `pharmaceutical capsules. When a large number of-capsules were to be filled, the use of Va large number of trays be came economically ineicient, but Anonetheless were used.

With powder-nlled `soft `gelatin capsules, `in which a powdercharge is packed `into a soft'gelatin shell, over which is placed va soft `gelatin cover and the two vcut out to form a powderalled capsule, suena process `is. not satisfactory.

Because the powderis not capable of transferring` hydrostatic pressure, itis `found 'that uthe capsules as formed are apt to bemisshapen with the powder unevely spaced, and thegelatinshell also distorted. We have found that if the Apowder-nlled capsules are tumbled, or agitated, the powder is shaken and then becomes Vmore freeilowing and by continual Vpounding action, any irregularities are reduced so that 4a smooth, rounded, even capsule may be obtained. 'At the same time, the seal line may shift until it is symmetrically on the capsule, if the hlm` temperatures and tensions are correct, and there are obtained smooth, evenly formed, perfectly shaped soft gelatin capsules. l

These moist capsules are extremely tender an are easily deformed or pressed out of shape. We have iound that it is particularly convenient `and economical to agitato the capsules in a rotating drum, a standard` pharmaceutical pan-coater being satisfactory for this purpose.

As the capsules are formed, they may be transfcrred by an air blast from the capsule filling machine to the rotatingdrum or pan. The tumbling they receive duringfthe transfer partially aids in shaping them, and causes them to become slightly air-dried, sufciently so that they do not as readily stick to each other. i Frequently'at `least `part of the capsule is coated with an oil, and this also aids `in preventing the capsules from sticking to each other.

The air blast from vthe conveyor keeps aconstant current of cool, dry air flowing through the drum. An -additional vblast of dry air may beV used but is normally unnecessary, The conveying blast can be directed so as to cause the capsules to be carried to the bottom of the pan.. As the pan rotates, and as they are tumbled, they progress towards the mouth of the pan, from which they may ylie permitted to freely Atali into single layer trays. By the time they fall into the trays, the capsules have a symmetrical shape, have a thin oil film,` and are suniciently air dry that they will not deform from their own weight or the `few inches fall into a trayand may be permitted to fall into the tray in which they are spread by hand 4until a-single vlay-er 4covering substantially the entire tray is obtained. The filled tray may then be replaced by an empty tray and the iilledtray allowedl to dry. We prefer to stack the-trayswith airncirculation spaces between, in atray drier.

In the tray drier, dry air 4is circulated over `the trays of capsules. Because of `the.drying'characteristics ofthe capsules, the amount of moisture that is lost in the rotating pan is comparatively high for the time involved. The rate of moisture removal'in the tray drier is slower; but it is found that in a matter o approximately lf2 to 24 hours,

the capsules will `have been sufliciently dried to become iii-m, in which form they may be moved, if handled gently.

` If permitted to dry suiilciently for packing and handling, itis found that the .capsules must be permitted to remain in the tray drier at a temperature of approximately 65 lik-80 F. and a relative humidity of less than about 40%, for not less `than 3-5 days. For small scale production, this is satisfactory, but with large scale productio-n the space occupied by the traydriers is cost- 1y. The amount'of moisture removed in the last few days is only a .small proportion of the total, butnonetheless it must he removed to provide satisfactory capsules. i

We have found that after .approximately 12. to 24 hours `in the 'tray drier, thefcapsules are suf ciently Yrigid that they Willcnotdeform'if placed in baskets to a depth of Uwelveinches `or more.

The capsules may be dumped from the tray into the basket and permitted to stand in the basket, which is perforated to permit dry air to circulate, for a period of about 3 to 5 days. In this manner, the duration of the expensive stage of tray drying is out to a minimum and the capsules are stored in baskets, in which they do not occupy such large spaces in the air-conditioned rooms and in which they may be kept after they are dried for periods of weeks, or until used in the final packaging or finishing operations. The use of the three-stage drying procedure in which each stage is modified according to the characteristics of the capsules at that particular time, provides a very efficient and economical method of drying our capsules. The process is shown diagrammatically in the drawings. Figure 1 shows the three stages of drying at (a) drum drying, at (b) tray drying, at (c) basket drying, at (dra single layer of capsules in a tray. Figure 2 shows a detail of the basket nesting.

In the drawings, the pan-coater Il is rotated as the capsules l2 are introduced by an air conveyor I3 and tumbled from the conveyor into the single layer tray M. As the second phase is shown in Figure l, b, a tray drier l5. The dry air supply lli and exit air Il are diagrammatically illustrated. As the third phase is shown in Figure l, c, a basket drier i8 showing how the baskets may be stacked to conserve space. Dry air iiows in through an inlet I9, through the stack of baskets and out the top 2U.

At Figure 2 is shown a detail of basket con.. struction in which a bead 2l lits into a groove 22 in the bottom of a basket to support the upper baskets, and lock the stack. Other modifications may be used. The one shown is neat, clean and economical.

The coating pan, tray drier and basket drier are all well known items of equipment, and various modications and equivalents may be used. Our invention lies not in the individual components but in their combination and the method of use.

A powder-filled capsule was manufactured,

containing an anemia preparation, from a gelatin film approximately 3%000" thick. The capsules were approximately s in diameter and 1/2 long. These capsules were tumbled `in an 18" diameter pan-coater into which the air conveyor introduced a large quantity of air at a temperature of approximately 65 F. and a relative humidity of about 20-30%. The capsules as they were delivered therefrom fell into a single layer tray on which they were spaced so as to provide a single layer in which the capsules were adjacent to or touching each other without resting on or deforming the adjacent capsules. A tray 24 X 32 held approximately 1500 capsules. The trays were stacked in a tray drier, sufficient space being allowed to permit air to circulate between the adjacent trays. After 12 to 24 hours, the capsules were transferred to the drying baskets. Baskets about 17" x 24 and 9" deep held approximately 15,000 capsules. They were stacked as the air was circulated through the bottom of the baskets to evenly dry the cap-l '4 three days', after which time the capsules were in their finished, hard, and dry condition.

The exact amount of drying in each of the stages may be varied over reasonable limits, depending upon the initial composition and the exact temperatures being used; the gelatin is harderat lower temperatures and will resist more handling, but a longer time is required for the drying.

Having thus described our invention in a manner to render it clear to those skilled in the art, we claim:

1. The method of drying soft gelatin capsules which comprises tumbling soft gelatin capsules until evenly formed and partially dried, transferring to single layer trays, spreading the capsules in a single layer therein, drying until sufficiently rm so as not to deform when packed in multi-layer packing, transferring to multilayer baskets, and drying until hard.

2. The method of drying soft gelatin capsules which comprises the steps of subjecting the soft gelatin capsules to cool, dry air while simultaneously tumbling the capsules for a suicient period to prevent their sticking to each other, and to cause them to assume an even, rounded symmetrical configuration, transferring them to single layer trays, spreading the capsules in a single layer therein, subjecting them to dry air until sufficiently firm that they may be handled, transferring them to multi-layer baskets, and subjecting them to dry air until commerciallydry.

3. The method of drying soft gelatin capsules which comprises tumbling powder-nlled soft gelatin capsules while simultaneously subjecting them to cool dry air until the capsules are sufiiciently rm not to stick to each other and are symmetrically shaped, transferring them to fiat single layer trays, spreading the capsules in a single layer therein, subjecting to dry air until sufciently firm that they may be handled, and transferring them to multi-layer baskets, and subjecting them to dry air until commercially dry.

4. In a method for drying powder-containing soft gelatin capsules, the steps which comprisetumbling powder-containing soft gelatin capsules in the presence of dry air until evenly formed and partially dried, transferring to a single layer tray, spreading the capsules in a single layer therein, and subjecting the capsules to dry air until at least sufficiently firm that the capsules may be convenientlyhandled.

5. The method of drying and shaping soft gelatin capsules which comprises tumbling soft gelatin capsules in a dry atmosphere until evenly formed and partially dried, transferring to single layer trays, spreading the capsules in a single layer therein, drying until sufficientlyv firm so as not' to deform when packed in multilayer baskets, transferring to multi-layer baskets, and drying in said baskets until commercially dry.

6. The method of drying and shaping soft gelatin capsules which comprises tumbling soft gelatin capsules in a dry atmosphere until evenly formed and partially dried, spreading the capsules in a single layer, contacting them with a d ry atmosphere until sufficiently rm so as not to deform when packed in multi-layer containers, transferring to multi-layer containers, and drying in said containers until commercially dry.

v 7. Iny a method for drying soft gelatin cap-` sules, the steps which comprise tumbling soft gelatin capsules in the presence of a dry atmosphere until evenly formed and partially dried, subsequently spreading the capsules in a single layer and contacting the capsules with a dry atmosphere until at least sufficiently rm that the capsules may be conveniently handled.

FRANK EDWIN STIRN. ARTHUR SINCLAIR TAYLOR.

6 References Cited in the le of this patent UNITED STATES PATENTS Number Name Date Baker Aug.. 12, 1924 Garnsey Sept. l, 1925 Brown Dec.` 11, 1928 Dent et al. Jan. 26, 1943 Davis Feb.. 24, 1948 Sartorius Mar. 6, 1951