Applications of buffers || Physical Pharmaceutics

Applications of Buffers..
This presentation provides an overview of definition of buffer, application of buffers in pharmaceutical formulations including opthalmic preparations, parenteral preparations, tablets preparations, etc.
Buffers in physiological system including
blood, lacrimal fluid, and urine etc. are abstracted.

1. APPLICATIONS OF BUFFERS PRESENTED BY : HINA TOUSIF

2. BUFFERS Definition: Buffers are defined as aqueous solutions (or) mixtures of components which prevent (or) resist any change in the pH of the solution, when small quantities of acids (or) bases are added .

3. Applications of buffers Buffers in pharmaceutical formulations 1. . Buffers in ophthalmic preparations Tears have a great degree of buffering action . Due to this eyes can tolerate pH ranging from 3.5 -10.5 without any discomfort . Ideally an opthalmic preparations should have a pH equivalent to lacrimal fluid, it resist p H adjustments. Opthalmic with p H ranging from 6.5- . 8.5 do not cause any corneal damage. E.g : Borax buffer, Sodium citrate buffer etc.

4. 2. Buffers in the tablets (or) capsule preparations B uffers in tablets & capsules helps to maintain the pH of the media surrounding the drug particles also enhance absorption of the drug especially incorporated in antacids to reduce gastric irritation. E.g: Magnesium carbonate, Sodium bicarbonate & Sodium citrate.

5. 3.Buffers in parenteral preparations In order to maintain the physical & chemical stability of the parenteral preparations, it is necessary to maintain the pH of the preparations and desired levels. The most ideal pH of parentral preparation is “ 7.4 ”. E.g: Acetate, Citrate, and Glutamate.

6. 4. Buffers in ointments & creams Generally pH of a topical preparations changes upon storage. Therefore buffers are added to maintain the pH with in the physiological range [in order to maintain stability of drugs and bases]. E.g: Phosphoric acid buffer.

7. II.Buffers in physiological system Biological buffers maintain the pH within the physiological range by converting strong acid & bases to weak acids & bases. 1. . Blood :- The physiological PH range of blood lies between 7.0- 7.8 . It is usually maintained at pH of about 7.4 by primary & secondary buffer, present in plasma and erythrocytes. Any deviations of blood pH from this PH range may result in death. E.g: Oxyhaemoglobin protein buffer .

8. 2. Lacrimal fluid (or) Tears The physiological pH range of lacrimal fluid is 7.0 – 8.0 . It is usually maintained at pH of about 7.4 . Lacrimal fluid posses high degree of buffering capacity. It allows dilution with neutral distilled water upto 1:15 without any alteration in its pH. E.g: Borate, Citrate, and Phosphate .

9. 3. Urine :- The physiological range of urine lies in between 4.5- 7.8 . It is usually maintained at about pH 6. . When pH of urine decreases below normal range (or) become acidic, kidney bring it back to normal value by excreting hydrogen ions. Similarly when the pH raises , H + ions are retained by them. E.g: Ammonia and Phosphate.