Wednesday, April 8, 2015

Pharmaceutical Mixtures

Mixtures in Pharmacy are aqueous liquid preparations which contain suspended, insoluble, solid substances and are intended for internal use. The insoluble particles may be held in suspension by the use of suitable suspending or thickening agents since the insoluble substance does not make mixture very viscous.

The insoluble substance in mixtures must be in a very finely divided state and it must be uniformly distributed throughout the preparation. This is accomplished by the use of colloid mill, special methods of precipitation and suspending agents.

There are three main reasons for having the insoluble substance in as fine a state of subdivision as possible:

(1) The more nearly the colloidal state is approached by protective such as kaolin, magnesium trisilicate, and magnesium phosphate the more active they become as adsorbents and protective when in contact with inflamed surfaces. 

(2) Finely divided particles are suspended more readily and settle out much more slowly than large particles, thus enabling the patient to obtain uniform doses of suspended substance. Homogenous mixtures are especially desirable when administering medication to form an evenly distributed, soothing, protective coating on the gastrointestinal tract. 

(3) The palatability of many preparations is enhanced by the use of colloidal suspending agents.

Mixtures should be accompanied with a “Shake Well” label.

Preparation of Mixtures

Brown Mixture, NF

Other Names: Mistura Opii et Glycyrrhizae Composita; Compound Opium and Glycyrrhiza Mixture NF XI; Mistura Glyceyrrhizae Composita; Compound Mixture of Glycyrrhiza.

Glycyrrhiza Fluidextract               120ml
Antimony Potassium Tartrate         0.24g
Paregoric                                       120ml
Alcohol                                           30ml
Glycerin                                        120ml
Purified Water, q.s.                   __________
             To make                          1000ml

Mix the fluidextract with the glycerin and 500ml of purified water, add the antimony potassium tartrate dissolved in 12ml of hot purified water. Add the other ingredients and enough purified water to make the product measure 1000ml.

Use: For coughs, often in combination with ammonium chloride.
Dose: Usual, 5ml

Note: This formula in which glycyrrhiza extract is replaced by the fluid extract will contain a precipitate, but it is intended to be dispensed without filtering, to retain its universally known classification as a mixture.

Kaolin Mixture with Pectin, NF

Other Name: Ka – Pek (APC)

Kaolin                                 200g
Pectin                                    10g
Tragacanth, powdered            5g
Benzoic Acid                          2g
Glycerin                              20ml
Peppermint Oil                0.75ml
Purified Water, q.s.         ________
          To make                 1000ml 

Mix the kaolin with 500ml of purified water. Triturate the pectin, powdered tragacanth and sodium saccharin with the glycerin and add to this, with constant stirring, the benzoic acid dissolved in 300ml of boiling purified water. Allow the mixture to stand until it cools to room temperature and all the pectin is dissolved. Add the peppermint oil and the kaolin – water mixture, mix thoroughly, and finally add sufficient quantity of purified water to make 1000ml.

Uses: Adsorbent and demulcent. Agents cause adsorbent in diarrhea capable of being adsorbed as for instance diarrhea of food poisoning or dysentery.

Note: To obtain a product with suitable consistency when larger amounts are prepared, the quantity of tragacanth and, if necessary, of pectin may altered. However, if the proportion of pectin in the formula is altered by more than 10 percent, the pectin content of the preparation must be clearly stated on the label.