Single Punch Tablet Machines
Tableting machines are commonly used in pharmaceutical industry. They are
high-speed machines that create thousands of tablets in a small period. The
compounding pharmacist uses a variation of these machines. It is called a single-punch
tablet press and makes one tablet at a time. A "punch" has two pieces of casted
tubular metal. The bottom metal piece has a small cavity in one end of the tube;
the top metal piece has one end that is tapered into a small rod that will just
fit into the small cavity in the other piece. The rod does not go all the way
to the bottom of the cavity, but leaves a small gap. The punch is fitted into
a press so that when the handle is depressed and released, the rod goes into
and then comes out of the bottom piece. To make a tablet, the powder material
is placed into the bottom piece, and the handle is depressed and released. The
powders are compressed and occupy the size of the gap designed in the punch.
Punches come in many sizes which allows the production of tablets of different
sizes and compression strengths. But each punch is a matched set; it is not
possible to interchange the top and bottom pieces of different punches.
Chewable tablets, effervescent tablets, and compressed tablets can be made
using a tablet press. Chewable tablets are generally made using mannitol because
it has a sweet, cooling taste and is easy to manipulate. Other ingredients may
include binders (e.g., acacia), lubricants (e.g., stearic acid), colors, and
flavors. The powder mixture is prepared, the desired quantity of mixture is
weighed, and then pressed with a single-punch tablet machine.
Effervescent tablets generally contain ingredients such as tartaric acid,
citric acid, and sodium bicarbonate. These powders would be appropriately mixed
and pressed into tablets using the same procedure as chewable tablets. They
will not require a disintegrant since they will effervesce when placed in water.
Compressed tablet mixtures generally contain the active drug, a diluent (e.g.,
lactose), a disintegrant (e.g., starch), and a lubricant (e.g., 1% magnesium