Dosator method

An independent method uses a volumetric fill by a modified dosator method. The piston inside the dosator is narrower than those used for powder filling, and this allows air to flow between the piston and the dosator wall. The dosator is lowered into the pellet bed, but in this case, there is no compression applied. A vacuum source is applied from above the piston to retain the pellets as the dosator is moved above the capsule body. Once over the capsule body, the vacuum is removed, and the ejection of the pellets is aided by an air jet. 

Fig. 24 The effect of percentage of sodium lauryl sulfate in the formulation on the dissolution of hydrochlorothiazide from capsules containing dicalcium phosphate as filler, 0.75% magnesium stearate, and filled on a dosator machine with 300 N tamping force (USP method 2, 900 mL 0.1 N HC1, 50 rpm). (Adapted from Ref. 71.)... 

Auger or Screw Method. This was the first mechanism used in industrial-scale machines, although the dosator and piston tamp mechanisms have now largely superseded it. The capsule body in its holder passes beneath the powder hopper on a turntable. The powder is fed into the capsule body by a revolving archimedian screw. The auger rotates at a constant rate so the fill weight is related to the duration of filling that is related to the speed of rotation of the turntable. 

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