Diagnostic Pharm Agents Flashcards
3 units of availability
- SDU Single dose unit
- Multiple dose preserved unit
- Multidose preservative free (MDPF)
Single dose unit
One opened, should be used and discarded right away. Contains no ingredient to stop microbial growth. AKA preservative free (PF)
Multiple dose preserved unit
Intended for repeated use
Contains preservative, a chemical with antimicrobial agent. Will kill or limit microorganism growth.
Most common preservative in eye drops: Benzalkonium Chloride (BAC or BAK)
Most common preservative in eye drops:
Benzalkonium Chloride (BAC or BAK)
Multiple dose preservative free unit
For repeated use. Has one way valve that dispenses one sterile drop only. The tip closes after each use and filter protects solution from airborne microorganisms.
6 Formulations
Ophthalmic solution Ophthalmic suspension Ophthalmic gel Ophthalmic emulsion Ophthalmic ointment Ophthalmic preparations (sterile)
Ophthalmic solution
Aqueous solution containing saline and buffering salts to maintain pH from 5-8. Comfortable upon instillation, allows solution to be stored for a long period (2 years).
Many contain polymers (cellulose commonly) or viscolizers. Viscosity depends on polymer used and amount.
Ophthalmic suspension
Heterogenous compound- contains solid particles dispersed in solute to increase contact time. Milky appearance. Must shake to disperse particles from sedimentation. Particles are small enough to not irritate surface of the eye.
Ophthalmic gel
Highly viscous solution with saline aqueous base and micoadhesive polymer such as polycarbophil. Bioadhesion attaches drug to biological tissue and increases contact time on ocular surface.
*Blurs vision- take before bed
Ophthalmic emulsion
Prepared by dissolving active ingredient into oil phase. Emulsifying agents and water (two or more liquids) are vigorously mixed to form uniform water-in-oil emulsion.
Preparation reminds intact and does not separate. Has milky appearance.
Ophthalmic ointment
Non-aqueous preparation. Base is oily such as petrolatum, paraffin oils, lanolin
Melting point near body temp.
2-4x longer contact time.
Ophthalmic preparations (sterile)
Prepared under sterile conditions by law. By Rx only
2 forms of presentation to ocular surface
Instillation of eye drop
Application of gel or ointment
How to instill eye drop into eye
Delivered to lower cul-de-sac or inner canthus.
Avoid cornea- will bounce off.
Close eyes for short time.
once eye drop is instilled, it is absorbed into
Cornea and conj. 5% of Active drug absorbed. only 1% reaches aqueous because it gets washed out by aqueous humor through trabecular meshwork and outflow.
