Contact time administration route

Although the use of a buffer will aid in reducing the risk of precipitation upon dilution, there are pH, concentration and buffer type limitations. Physiological compatibility will depend on factors such as the route of administration, tonicity, and contact time. Other factors such as chemical stability as a function of pH must also be considered. Table 4 lists some marketed... 

Consequently, frequent instillation of eye drops is required, resulting in pulsed administration and patient noncompliance. Clearly, the main prerequisite for absorption of drugs into the eye is good corneal penetration and prolonged contact time with the corneal epithelium. Many intrinsic barriers, such as the cornea barrier, blood-aqueous barrier (BAB), and blood-retinal barrier (BRB), restrict ocular drug delivery (Figure 51.2). The barriers related to topical drug administration route are as follows. 

According to national legislation the label mentions the dosage form (eye lotion), the route of administration (ocular use), the patient information for the intended use. If necessary an eye cup should be supplied. The patient should be instructed as to the proper use of the eye lotion and eye cup, the contact time of bathing the eye and cleaning of the eye cup. The device should be thoroughly rinsed and cleaned before and after use. 

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