January 25, 1952
One of the instruments used by University of Wisconsin pharmacy researchers to improve the quality of medicinal tablets--of which aspirin is one of the most familiar examples--is the oscilloscope.
The machine which is being operated here by Eino Nelson, an assistant in the UW School of Pharmacy, is a valuable research tool because it gives scientists a record of what happens during the actual manufacturing process of compressing granulated drugs and medicines into tablets which can be swallowed easily.
Have you ever wondered, just before popping an aspirin in your mouth, how is was made, what held it together, and why it dissolved in your stomach?
Probably you haven't, but University of Wisconsin scientists know that aspirin is nearly an ideal tablet.
It's hard and yet it disintegrates quickly.
But most tablets aren't as easy to make as aspirin. Researchers in the School of Pharmacy at Wisconsin -- Profs. Louis W. Busse and Takeru Higuchi, assisted by former graduate students R. D.. Arnold and S. J. Tucker, have uncovered new facts about tablet-making techniques.
They presented some of their ideas before the Buffalo Convention of the American Pharmaceutical society last August.
And work along these lines is being continued, with the help of graduate students William Strickland, Eino Nelson, and Narsimha Rao.
Just to make things interesting, all substances cannot be compressed into tablets by using the same methods.
For instance, in an aspirin tablet, the necessary lubricant and binding characteristics are inherent in the aspirin itself.
So it is only necessary to combine it with 10 per cent starch, which serves as a disintegrating agent.
Result -- a very satisfactory tablet.
But, to make an ordinary sleeping tablet, the active ingredient of which often is sodium phenobarbital, requires the addition of lubricants, binders, and disintegrating agents, as well as a "filler" to give it the necessary bulk.
Only then does a satisfactory tablet result. - more - ad one -- ablet.s
Thus, selection of the proper chemical components of a tablet is important, since they can influence its hardness and density.
An ideal tablet is hard enough to withstand transportation and handling, and yet disintegrates rapidly in a glass of water or in the stomach.
Obviously tablet making is a complicated business, because so many factors must be considered. The scientists say that the essentials of tablet manufacture are:
Wisconsin scientists know that the "physics of tablet compression" are important, and they want to know more about such factors as particle sizes, moisture content, granule hardness and density, and the amount of compression necessary to make the tablet. And they are using scientific instruments to help them find the answers.
A glass gadget called a pycnometer measures the porosity or void space (space between the granules in a tablet).
Bulk volume is determined in a complicated array of tubes and devices -- a "high precision helium densitometer."
And now they have another machine, an oscilloscope, which will give them valuable information under actual manufacturing conditions.
This instrument, the "cathode-ray oscilloscope" is its official name, looks somewhat like a small television set with a camera on top.
It is connected electrically to a signal generator, and to the machine which punches out the tablets. After the oscilloscope is warmed up, the chemical ingredients of the tablet are fed into the tablet machine, which compresses granulated material into tablets.
Electrical signals from the tablet machine to the oscilloscope show up on the screen as wavy bluish lines, and provide a record of the energy expended by the machine punching out the tablets.
Meanwhile, the attached camera takes pictures of the pattern on the screen."With this new oscilloscope set-up," says Professor Busse, "we will be able to get a continuous flow of information during tablet manufacture.
These data, together with facts obtained from other instruments, will help us to learn a great deal more about tablet making." -more- ad two--tablets Funds for this research are provided by the Wisconsin Alumni Research foundation, plus equipment grants from Smith, Kline, and French, Inc., Parke, Davis and Co., pharmaceutical companies; and the F. J. Stokes Co., manufacturer of pharmaceutical equipment.
Tablet making is not new; compressed tablets were invented in the 19th century.
But even today, when great quantities of aspirin, anti-histamines, and all sorts of other drugs are sold, the manufacture of tablets is still somewhat of a hit-or-miss proposition.
Differences in chemical and physical properties are all-important in tablet making and Wisconsin scientists want to know more about them.
They are trying to take the guesswork out of the compounding and manufacture of tablets, and make it a science rather than an art.