A medication monitor and fluorescein technique designed to study medication behaviour

Methods were developed to study medication behaviour, in order to obtain accurate and detailed information on the patterns of drug-taking in medication with eye drops. A medication monitor was designed, which recorded the date and hour each time the medication bottle was opened. A fluorescein technique was designed to study the ability of patients to administer the eye drops into the conjunctival sac. Some problems in the measurement of medication behaviour are discussed. In a group of patients with open-angle glaucoma, for whom pilocarpine eye drops three times daily had been prescribed, 18% of dose intervals had a duration of 12 h or more and 11% had a duration of 4 h or less. Fluorescein tests indicated that the patients were usually able to administer the eye drops correctly.

A long-term implantable aqueous delivery system for the external rabbit eye

An implantable system is described which continuously delivered an aqueous solution to the external surface of six rabbit eyes for 6 weeks. A polytetrafluoroethylene tube was implanted in the superior conjunctival fornix 4 weeks prior to the implantation of the Infusaid pump. The pump provides a fluid source which is easily refilled and requires no batteries or external power source.

Topically applied pilocarpine. Human pupillary response as a function of drop size

Previous studies with use of animal models have shown that, for topically applied ophthalmic drugs, the fraction of dose absorbed into the eye is increased as the volume in which the drug is instilled is decreased. Such findings have not previously been confirmed in humans. In the present study, the miotic response to instilled doses of 20 and 50 microL of 0.5% pilocarpine hydrochloride was compared in ten adult human volunteers. Although the 20-microL drop represents a substantial dosage reduction, the miotic response was essentially equivalent to that obtained with the 50-microL drop. These findings imply that, due to the large drainage loss of topically applied ophthalmic drugs, volumes delivered by commerical ophthalmic droppers may in some cases be larger than required to achieve the desired response.

The legal setting in prescribing drugs

By training and experience physicians generally prescribe drugs with only the patient in mind. In today's environment it is essential that the physician stop and think of himself also. We are all aware of malpractice problems, which begin in the physician's office or at the hospital and, if severe, end in court. The ophthalmologist must now consider what a disgruntled patient can find in writing to use in court. Hospital records and physician's charts are now just the beginning point. The Physician's Desk Reference (PDR), the published literature, the package insert, the promotional material of pharmaceutical companies, the internal records of drug companies, the pharmacists' records, and the data now obtainable from government agencies all provide happy hunting grounds for a competent plaintiff's attorney. The ophthalmologist needs to be keenly aware of these potentially adverse resources and how they can be used against him. He also needs to know the alternatives available to him. Once these matters are brought into clear perspective, both the patient and the ophthalmologist will be better off.

A method for delivery of ocular medications

Many patients have difficulty placing medications into their eyes. Using a pair of inexpensive plastic sunglasses, a patient designed a simple device for instillation of ocular drops.

Evaluation of a soluble sustained-release ophthalmic delivery unit in the dog

A 5-mg hydroxypropyl cellulose soluble ocular insert was evaluated by placement in the upper and the lower conjunctival and bulbar nictitating membrane fornices in normal dogs. The insert was easily placed in the conjunctival fornices, but was difficult to place in the bulbar nictitating membrane fornix. The conjunctival inserts did not produce irritation of the cornea and the conjunctiva. Placement of the inserts beneath the nictitating membrane produced local irritation and chemosis. The sites of highest to lowest retention for the insert were upper conjunctival fornix, bulbar nictitating membrane fornix, and lastly, lower conjunctival fornix. Dissolution was nearly complete in 8 hours.

Avoiding adverse effects of cycloplegics in infants and children

Cycloplegics are very safe and useful medications. To avoid the unpleasant side effects of these medications, six precautions are considered. They are: 1. dosage, 2. cycloplegic selection, 3. toxic reaction, 4. biologic variations, 5. topical anesthesia, 6. environmental temperature and humidity.

Continuous lavage in (chemical) corneal lesions

In a small number of patients with severe chemical corneal damage and in a few patients with corneal ulcers, continuous lavage of the conjunctival sac with a mixture of the patient's own serum, tissue culture fluid and various medicaments was carried out with great success.

Ocular hypotensive efficacy of topical epinephrine in normotensive and hypertensive rabbits: continuous drug delivery vs eyedrops

The ocular hypotensive efficacy of continuously delivered epinephrine is compared to that of pulsed doses provided by eyedrops in both normotensive and hypertensive rabbit eyes. In normotensive eyes, 2 microgram/hr and 4 microgram/hr epinephrine delivered into the tear film continuously for 12 hours reduces intraocular pressure as well as eyedrop pulses of 0.5% epinephrine hydrochloride or 2% epinephrine bitartrate (doses of 500 and 1100 microgram, respectively). Ocular hypertension induced by an intragastric water load in rabbits is significantly inhibited by continuous delivery of epinephrine at the rates of 3 or 6 microgram/hr, or by 2% epinephrine bitartrate (1% free base) eyedrops. Epinephrine delivered continuously at rates of 2-6 microgram/hr for 6 to 12 hours (12-72 microgram total) has hypotensive efficacy equivalent to 15 to 40 times as much epinephrine applied once in eyedrops. Epinephrine bitartrate eyedrops reduce tear film pH well below normal. Continuous delivery of epinephrine bitartrate does not reduce tear film pH below normal levels.

Penetration routes of topically applied eye medications

Tritium-labeled hydrocortisone acetate and pilcarpine hydrochloride solutions were topically applied to the eyes of rabbits. In one group of animals, the drugs were excluded from contact with the cornea by a cylindrical well glued to the eye surface. In another group, the drug solutions were allowed contact with the entire anterior surface of the eye. Total application time in all cases was five minutes, then the eyes were flushed with saline. Samples of aqueous humor, stroma, and iris-ciliary body were taken after five, 20, 35, 65, and 125 minutes and counted in a liquid scintillation counter. With hydrocortisone, up to 70 times more drug reached the stroma when the cornea was exposed; 40 times more reached the iris. Peak stromal levels occurred by 20 minutes, dropping to one third of peak value by two hours. With pilocarpine, about five times more drug reached the iris-ciliary body when corneal access was allowed; the level peaked in about five minutes. These results illustrate the important role of tear film distribution and blinking in delivering remotely applied drugs over the cornea with subsequent entry to interior sites.

Intraocular irrigating solutions. A comparative study of BSS Plus and lactated Ringer's solution

Isolated human corneas maintained normal corneal thickness and endothelial ultrastructural integrity throughout a three-to four-hour period of perfusion of BSS plus to the endothelial surface. By comparison, only one of six human corneas perfused with lactated Ringer's solution was able to maintain normal thickness and ultrastructural integrity. The other five corneas perfused with lactated Ringer's solution showed various degrees of endothelial cell breakdown and corneal swelling during three hours of perfusion. The results of these studies suggest that BSS plus is a better solution for maintenance of human corneal endothelium during long-term (one- to three-hour) surgical procedures.

Atenolol 4% eye drops and glaucoma. A double-blind short-term clinical trial of a new beta1-adrenergic blocking agent

We studied the effect of a single dose of atenolol 4% eye drops on 21 patients with primary open-angle glaucoma during a double-blind clinical trial. We monitored intraocular pressure (IOP), blood pressure, and pulse rate. At three and six h after medication, the average reduction of IOP was 7.3 and 4.1 mm Hg, respectively, compared to the baseline readings without medication. The reduction of IOP at four h after medication was 6.3 mm Hg compared to the pretreatment value. This corresponds to an average change from the pretreatment value of 22%. Blood pressure and pulse rate did not change significantly. We observed no subjective or objective ocular side effects. The duration of the effect of a single dose of atenolol 4% eye drops is approximately six h. Atenolol 4% eye drops may become a useful agent in the medical treatment of glaucoma if a long-term effect and no ocular side effects (especially a local anesthetic effect) can be proven.

Pediatric dosing considerations in ophthalmology

In almost all cases concerned with topically applied ophthalmic drugs, no distinction is made between adults and infants or children with regard to the concentration and amount of drug used. Even though maximal therapeutic effects are usually observed, there can be significant short- and long-term toxicity problems. Based on some modest assumptions it should be possible to reduce doses without sacrificing therapeutic effectiveness in infants and children up to three years of age. The overriding concern should be, however, potential toxicity problems which may exist in infants and children, in particular the neonate, due to their low body weight and the fact that in most cases, more than 90 percent of an instilled dose in potentially available to act systemically. Total body surface area can be used as a measure for determining potentially toxic doses in children. Especially for potent drugs, with both short- and long-term manifestations, toxicity considerations may necessitate some sacrifice in therapeutic effectiveness of a given drug or switching to an alternate drug in order to insure a reduction in toxic side effects.