Encapsulation (pharmacology)

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In pharmacology, encapsulation refers to a range of techniques used to enclose medicines in a relatively stable shell, allowing them to, for example, be taken orally or be used as suppositories. The dosage form is primarily for oil soluble actives.

[edit] Soft gel encapsulation

In 1834, Mothes and Dublanc were granted a patent for a method to produce a single-piece gelatin capsule that was sealed with a drop of gelatin solution. They used individual iron moulds for their process, filling the capsules individually with a medicine dropper. Later on, methods were developed that used sets of plates with pockets to form the capsules. Although some companies still use this method, the equipment is not produced commercially any more. All modern soft-gel encapsulation uses variations of a process developed by R.P. Scherer in 1933. His brilliant innovation was to use a rotary die to produce the capsules, with the filling taking place by blow molding. This method reduced wastage, and was the first process to yield capsules with highly repeatable dosage.

In 1949, the Lederle Laboratories division of the American Cyanamid Company developed the "Accogel" process, allowing powders to be accurately filled into soft gelatin capsules.

Since their inception, capsules have been viewed as the medium of more potent medicines than tablets, which are more commonly associated with weaker OTC drugs. For this reason, producers of drugs such as OTC analgesics wanting to emphasize the strength of their product developed the "caplet" or "capsule-shaped tablet" in order to tie this positive association to more efficiently-produced tablet pills. After the 1982 Tylenol tampering murders, capsules experienced a minor fall in popularity as tablets were seen as more resistant to tampering.

[edit] Two-part gel capsules

James Murdock patented the two-part telescoping gelatin capsule in London in 1848.

[edit] References

• L. Lachman, H.A. Lieberman, J.L. Kanig (1986). The Theory and Practice of Industrial Pharmacy (3rd Ed.). Lea & Febiger, Philadelphia. ISBN 0-8121-0977-5.