PH adjustment is done with weak buffers strong buffers are not used .
buffering agents which can be adjusted to isotonicity are available in USP , borate buffers ,phosphate buffers
Tonicity is adjustment :0.9% sodium chloride is isotonic with lachrymal fluid .
This factor is not so important in case of eye drops as eye can with stand to so much less volume of eye drop without adjusted to tonicity but it is preferred.
But in case of eye washes and lotions tonicity must be adjusted to so that it is isotonic with lachrymal fluid
For stability chelating agent is added and a suitable antioxidant if required is added.
For Eye preparations we can follow following methods of sterilization
1.Autoclaving
2.Heating with bactericides
3.Aseptic filtration through 0.22 micron filters
Ophthalmic solution and suspensions as are required to be sterile when they are dispensed or when they sold by manufacturer, except in some cases where some ophthalmic solution and Preparation which are not specifically required to comply with Example
iii] Phenyl ethyl alcohol: 0.5%
Provided that solutions used in surgery shall not have
Preparations which Contain one or more of suitable antimicrobial agent which will prevent growth of micro organisms.
BAK : 0.01% should not be used in solutions of nitrates + salicylates
PMN: 0.001%
Phenyl ethyl alcohol : 0.5%
And Provided that a solution used in surgery should not have any preservative and is packed in a single dose container further that FDA may direct authorize one of any other preservative or vary a concentration prescribed for being satisfied that its use gives equal assurance for preventing growth of micro organisms.
C : it should be be free from foreign matter.
D : It should be contained in bottles made either of either a neutral glass or soda glass specially to reduce amount of alkali released when it come in contact with aqueous preparation or in suitable container it is should not in any way be incompatible with solution.
The dropper to should be provided with containers of ophthalmic solution and suspensions should be made of neutral glass or of suitable plastic material and when supplied separately shall be packed in sterile cellophane or other suitable packing.
E : In addition to it should complying with labeling requirements , following particulars shall also be shown on label.
On containers:
i] The statement use solution with in one month after opening container.”
ii] Name and concentration of preservative used.
Iii] The words “not for injection”
On the label of container or carton or package leaflet.
1)There should be a special instruction given , regarding storage wherever it is applicable.
2) There should be a special cautionary regarding as warning. “If irritation persists or increase, discontinue use and consort physician”
B)Do not touch the dropper tip to any surface.
Ophthalmic ointments.
Ophthalmic ointment should be sterile when dissolved or solid in unopened container of manufacturer
Should be free from foreign matter.
Further it should comply with requirements for labeling laid down
Following details should be shown on the container or carton or packing leaflet.
i) There should be a special instruction regarding storage whoever applicable.
ii) There should be a cautionary regarding “warning: if irritation persists or increases discontinue use consult physician”