Sodium Chromoglycate Inhalation Medicament

In order that the invention may be well understood, the following Examples of compositions according to the invention are given by way of illustration only.

Commercially available ground crystalline lactose having an effective particle size of from 1 to 100 microns (less than 30% by weight greater than 60 microns, not more than 30% by weight less than 30 microns) was passed through an air classifier, set to remove material having an effective particle size of less than 30 microns. The product from the air classifier contained less than 4% by weight of material of less than 32 microns effective size. This product was then sieved through a sieve having a mesh aperture of 63 microns to produce a lactose product which contained less than 10% by weight of particles with an effective size less than 32 microns and less than 20% by weight with an effective particle size in excess of 62 microns as determined on an Alpine are jet sieve.

The medicament, e,g, sodium chromoglycate, or other material such as lactose which was intended to form the finely divided material was passed through a fluid energy mill in an air stream until the product contained at least 50% by weight of particles in the effective size range 2 - 6 microns as determined on a Coulter counter.

Compositions containing the desired proportions of the coarse and fne materials were mixed together in a planetary mixer and the mixture then passed through a 30 mesh sieve to remove or break up agglomerated particles.

The compositions were then put up in gelatine capsules containing about 40 mg of the composition (capsule approximately one-third full) and the ease of emptying of the composition from the capsule determined. The ease of emptying was assessed by mounting a pierced capsule in the capsule holder of the powder insufflator of French Patent Specification No. 1471722. The insufflator was then mounted in a hole in the side wall of a chamber connected to a bellows. The bellows are designed to suck air through the chamber, and hence the insufflator acting as the air inlet thereinto, at a rate of 1 liter per second. Each suck of the bellows lasted one second.

The capsule was weighed prior to mounting in the insufflator. The bellows were then operated to give seven one second sucks and the capsule reweighed to determine the amount of powder removed is related to the ease of fluidisation of the powder.

The compositions prepared and tested are set out in Table I. By way of comparison a composition containing no coarse diluent was prepared and tested in each case. Those compositions containing the coarse carrier were all found to empty from the capsule at a satisfactory rate, in general from 85 to 90% of the composition, whereas in the absence of the coarse diluent the emptying rates were much lower, about 15% or less, and were unpredictable.

By way of comparison a further series of compositions were prepared which contained coarse carrier material which possessed an appreciable proportion of particles with an effective size outside the range 30 - 80 microns. The emptying rates for these compositions are set out in Table 2.

From these results it will be seen that the rate of emptying of a capsule, containing a composition which comprises an appreciable proportion of particles whose effective size fell outside the range 30 - 80 microns, was very low and unpredictable thus rendering the administration of such compositions by inhalation unsatisfactory.