Danny H. Lewis

Fibrous Polymers for the Delivery of Contraceptive Steroids to the Female Reproductive Tract

Research and development on the application of controlled-release technology to fertility regulation was initiated in the late 1960s and has been accelerated in recent years.1’2 Since sustained-release doses obviate the problem of cyclic overdosing and underdosing associated with the conventional administration of steroids, the technology, in principle, affords a means of effecting an optimum pharmacological response with a minimum dose of exogenous steroid.3 Depending upon the half-life of the drug in plasma, the duration of the dose regimen, and the route of administration, the total dose can be reduced to 1/100 or less for continuous versus intermittant delivery.

Polymers Containing Pendent Insecticides

The fire ants Solenopis invicta and Solenopsis richteri, were accidentally imported into the United States from South America through the port of Mobile, Alabama. Present evidence indicates that richteri was introduced about 1918, and its spread has been only moderately successful during the succeeding 62 years. At the present time, richteri infestation is limited to a small region of northern Alabama and Mississippi. In contrast to this, Solenopsis invicta has been extremely successful at establishing itself in the southeastern United States. Since its introduction in the mid 1940s, this species has expanded its range to nine southern states encompassing more than 50-million hectares of land.1 This phenomenal rate of spread is accounted for by two factors. The natural spread of the ants via mating flights is ideally suited to avoid inhibition by natural and man-made barriers.2–4 Mating takes place in swarms which have a minimum altitude of 500 feet above the ground. Following mating, a queen may alight miles from her home nest. A second major factor in the rapid spread of the ants has been the influence of transport by man. Commercial movements of nursery stock and sod during the 1940s and 1950s, prior to the institution of quarantine procedures, greatly aided the introduction of the ants into uninfested regions.