Physical pharmaceutics 1 ph And Buffers

1. PH AND BUFFERS
ISOTINIC
SOLUTIONS.
BUFFERS: ARE THE SUBSTANCE WHICH MAINTAIN PH

2. Ph scale:
Discovered by the scientist sorsens:
ph scale:Ph Indicates the basicity and acidity in soln. Ph = power of
hydrogen/potential of hydrogen in con .
Sorsen explain ph scale in negative logarithm of hydrogen ion (H3o+)
Express:Ph= (-logH+) Ph is a important segment in pharmaceutical
preparations Required to stable the Dosage forms And storage
changes in ph they distrub in preparations / Disturbution
Ph scale Indicates 0-14 range ,0 strong acid, 14 strong base, 7 neutral
0-6 acid 8-14 base range

3. Applications
1. Identification parameter and elevation tool for raw materials , purity
and substances.
2 . Mostly control the pharmaceutical preparations.They,⬆️ the solubility
and stability of API.
3. Confirm of product 4 . Improving the purity of the substance.
5 Optimizing biological activity.
LIMATIONS:1 Dilute solution, 2. Not used to measure the high
value conc.

4. Determination of pH
Based on H+ ions
1 . Electrochemical method .Using electrodes acts as indicator
electrode / Reference electrode .Measures the potential changes in
the soln. H+ senstive measures. Also called as potenOtimetriy method .
Potential generate by
Advantages : accurate value and rapid and high sensitive
(H+) con. Alternatively used by to electrodes
Disadvantages: Expensive, not use for jels and viscous substances

5.  2. Colorimetric method : 1 test sample 2 standard sample/soln: in
Lab commercial available . The universal indicator is used ( mixture
of indicators). different colours measure ph range Based on the
colour change the indicator compare both test sample soln up to
same colour
 Advantages: visible easy , used to acid bases study
Dis : not accurate value show

6. BUFFRS:
 Maintain/ preparation of the Buffers / acid, base buffers .
 Buffers are (compound /mixture )of compounds that they prevents
reset change in pH on addition of small amount of acid and base.
 Buffer action : The Resistant in the change in ph is known as buffer
action .
 Buffer solution aqueous solution of acidic buffer and basic Buffer
.Weak acid it's is a conjugated base.
 Classification of buffers.
 1. acidic buffer : maintain the ph level less than 7 weak acid
conjugated base ex: ch3cooh + na= ch3coona
 2. basic buffer : weak acid and conjugated acid ex: nh4oh
 3 .neutral buffer: weak acid and weak base ex: acetic acid and
ammonium chloride

7. Characetersits of buffers
1 .Definte ph . 2. no changes in ph 3. strong time 4physiological 5.
stable 6 . Nontoxic 6 . Resistance to oxidation
Buffer action : and mechanism
1 .acidic buffer acid is added to h3o+ increase acidity
H30+ ch3coo- ch3cooh+ h2o no avabilty of h3o+ ions
2. Base is added increase oh .
Basic buffers ; base is added decrease the oh . Acid added increase
the h30+ level eg nh4cl---- NH4+ cl-

8. Buffer capacity and buffer
equation.
 BUFFER CAPACITY :REPRSENTS BY BETA INDICATES THE RATIO OF ACID
BASE
 Def: measure the magnitude of resistance amount of acid base is
required to change 1 unit ph
 Ratio of salt to in buffer , total buffer con
 Buffer equation: also called as Handerson bassel equation.
 purpose of is mainly determine ph of buffer 2 . Change in ph upon on
acidic buffer basic buffer
 Acidic buffer : log salt acid ph = pka +log salt acid
 Basic buffer ; ph= pka + log salt base
 stability of ph new drug development of NDD . Profile study
 fermention method .

9. BUFFERS IN BIOLOGICAL SYSTEM
and pharmaceuticasystem
1 Blood – ph of blood 7.4 maintain biological salts maintain homestasis
that’s help in to various biological process
2 plasma protein; acts as acid+ base buffer maintain the ph(serum
lipo protein)
3. Erthrocytes rbc and acid alchol ‘k’ salts
4 lacrimal fluid maintain ph 5. urine well maintain ph help in proper
function of kidney 6 enzymatic actions In stomach
PHARAMACEUTICAL SYSTEM :
1. PARENTRAL PREPRATION : 7.4 PH MAINTAIN EX INJECTIONS
2. OPTHAMALIC PREPRATIONS ;PH 7-8 EYE DROPS
3. OINTMENT AND CREAM ; 5.5 PH AROOUND NOT MAINTAIN PH CAUSES
IRRIATION

10. BUFFERS ISOTONIC SOLUTIONS
 ISOTINICITY : THESE ARE the solns which are having similar ph and
concentration osmotic pressure as our body fluids is called isotonicity
.
 METHOD OF ADJUSTING OF TONICITY ;
 1 NACL EQUAIVALENT METHOD 0.9 wv
 2 CRYOSCOPIC METHOD FREEZING METHOD DEPRESSION METHOD
 NACL EQUALVALIENT MEHOD;
Nacl and blood cell are equal up to 0.9wv no effect
the soln at low 0.9 the soln swell forms
the soln at high 0.9 causes the srink of cells
to proper maintain equal .

11. Cryoscopic method
 - 0.52 body fluilds is freezing point
 W%= 0/52-ab
Unadjusting soln 1% and 1% nacl addition od different substances
W=amount of adj substance ( salt) a= freezing point of unadjusting substances b=-1of freezing
point
MEASURMENT OF TONICITY ; 1 HAEMOLYTIC METHOD BLOOD CELLS 0.9
CONDTION
TEST SOLN + RBC = NO EFFECT THE TEST SOLN IS ISOTONIC
SWELL EFFECTS HYPOTONIC SRINK OF CELL HYPER TONIC
2 COLLGATIVE METHOD ; 1 .
VAPOUR PRESSURE L OW SOLN CON LOW
FREEZING POINT solute can lower freezing point 0.9% 0.82 isotonic solns.

12. kAlyan
b pharm