Symmetrel gets FDA approval

ISA exhibit Optimistically only an even split with pneumatics

miniature electronic instruments. The line, called the H series, includes con­trollers, recorders, indicators, and aux­iliary stations. Common to the line is a new shelf-mounting method and back-of-panel wiring concept. The latter, according to the Foxboro, Mass., company, can reduce the cost of large installations, simplify trouble-shoot­ing, and ease future computer tie-in. All the instruments can be provided with built-in transmitter power sup­ply.

The controller in the series, the Model 62H, can be purchased with a motor-driven set-point mechanism. This allows the set point to be adjusted by a pulse source, such as a computer's digital output. Alternatively, the con­troller can be converted in the field to include the motor-driven set-point as­sembly. A standard feature of the unit is a new integral amplifier which makes possible a balanceless-bump-less transfer from manual to automatic or automatic to manual by flipping a T-bar switch.

Another controller in the line, the Model 61H, is designed for control of short-time constant processes such as flow. A 4-inch strip-chart recorder, a concentric indicator, and a shelf-mounted vertical-scale indicator are available. Rounding out the line, auxiliary stations provide for manual adjustment of the 10- to 50-milliamp. d.c. signal for remote-manual control of final actuators or for remote set of a controller. One of the versions mul­tiplies the signal by a preset ratio.

Computer control, in both its super­visory and direct digital control forms, is reflected in the new computer-set

Synchro control stations from Moore Products, Spring House, Pa. Models are available for use with supervisory control computers to convert digital pulses directly into pneumatic set-point signals. For direct digital control, other models convert DDC pulses directly into pneumatic valve-operat­ing signals. The Synchro stations, Moore points out, can be switched from computer to automatic or manual and back without balancing pressures.

New differential pressure transduc­ers are available for the signal-generat­ing end of the control loop from GE's instrument department, West Lynn, Mass., and Leeds & Northrup, Phila­delphia, Pa. Such instruments gener­ate electrical signals representing pres­sure differences—across an orifice in flow measurement, for example. GE's light (20 pounds) Type 555 transmit­ter makes use of an electrical method for adjusting span, rather than the fulcrum point adjustment required with beam systems. The unit has ranges of 0 to 200 inches water and 0 to 850 inches water, with spanning of 20 to 100% of range.

Leeds & Northrup's transmitters, the 1912 and 1913, are designed to extend the company's line into the low-static-pressure region of measurement. They have a minimum span of 0.2 inch water and a maximum span of 20 inches wa­ter. The 1912 produces an output signal directly related to differential pressure and is linear with it. The 1913 is similar, but relates differen­tial pressure to flow through an orifice by extracting its square root with an internal element. The L&N units, like the GE, are force balance systems.

Du Pont is now allowed to market Symmetrel, a prophylactic drug to prevent Asian flu. The Food and Drug Administration approved the company's new drug application to sell amantadine hydrochloride as a pre­scription drug to prevent illness due to A2 influenza virus.

Symmetrel will be the first drug marketed by Du Pont. It will be sold only on prescription.

The synthetic drug is to be taken orally; it is not a vaccine or antibiotic. It acts by interfering with virus pene­tration of host cells, but does not con­flict with antibody production. Du Pont says that the new "preventive oral medication" provides possible imme­diate A2 influenza protection when taken after suspected contact and that protection continues as long as a per­son takes the drug.

Du Pont says the drug will be par­ticularly useful for persons suffering from debilitating diseases such as car­diovascular, pulmonary, renal, and metabolic disorders. It would be dan­gerous for these people to contract Asian flu. There is no guarantee, however, that every patient will be immune to the disease while using Symmetrel. The drug will also be useful in communities where there is an epidemic caused by an A2 virus.

The effectiveness of Symmetrel was first announced in April 1964. It was synthesized by Dr. Marvin Paulshock and Dr. John C. Watts of Du Pont. For example, they nitrated adaman­tane with concentrated nitric acid and acetic acid at 140° C. to yield 1-nitro-adamantane, which in turn was re­duced to the 1-amino derivative. The parent adamantane was synthesized by a modified method in which cyclo-pentadiene dimerizes to dicyclopenta-diene. This diene was hydrogenated and the product catalytically con­verted to adamantane.

Symmetrel Preventive oral medication

26 C&EN OCT. 31, 1966