Primaxin in the treatment of acute bacterial pneumonia in adults

Imipenem (N-Formimidoyl thienamycin) (MK-0787) is a new beta-lactam carbapenem antibiotic. When it is combined with the renal dipeptidase inhibitor cilastatin (MK-0791) the combination is known as primaxin. In this study 28 adult patients (24 males and 4 females) with acute bacterial pneumonia were treated with primaxin. Twenty-one patients were evaluable and 20 (95%) were clinically cured of their pneumonia. Bacteriological cures were demonstrated in 84% of the cases. One patient with a susceptible Pseudomonas aeruginosa failed. Major complications or toxic reactions included antibiotic associated diarrhoea in one patient; hypotension in one patient; increased grand mal seizures in one patient and elevated liver function studies in one patient. Results of this study suggest that primaxin will be useful in the treatment of a variety of serious Gram-positive and Gram-negative pneumonias. The true incidence of possible toxic reactions with this drug is not known at this time and awaits further experience.

Treatment of alopecia areata with diphencyprone

26 patients with alopecia areata were treated topically with diphencyprone. 10 had alopecia universalis, 7 alopecia totalis and 9 had alopecia areata. The treatment lasted from 4 to 14 months. In 13 patients a little response was obtained; only in 1 case it was satisfactory. Factors that appear to influence these results are discussed.

Diphenylcyclopropenone: examination for potential contaminants, mechanisms of sensitization, and photochemical stability

Diphenylcyclopropenone (DPCP) has recently been reported to be a potent contact sensitizer for the treatment of alopecia areata. DPCP is nonmutagenic in the Ames assay. Studies on chemical purity, stability, and mechanisms of action are lacking. DPCP is synthesized by cyclization of alpha, alpha'-dibromodibenzylketone. The latter elicits a reaction in guinea pigs sensitized to DPCP. We examined a commercial sample of DPCP by gas chromatography--mass spectrometry for the presence of contaminants. The stability of dilute solutions of DPCP in ethanol and cyclohexane to fluorescent light, sunlight, and heat was followed by ultraviolet (UV) spectrometry. The isosbestic point and half-life for this reaction were determined. We found no original or intermediate reagents in our sample. DPCP was found to decompose, forming diphenylacetylene on exposure to both sunlight and fluorescent light in less than 2 weeks. Samples shielded from the light at -70 degrees C and at room temperature were stable over a 4-week period. The extent of decomposition was the same in both ethanol and cyclohexane. It is possible that DPCP may act as a prosensitizer with the actual sensitizer liberated by a photoactivated intermediate (stable, metastable, or unstable) or a combination of these.

A multiclinic randomized study of the comparative efficacy, safety and tolerance of imipenem/cilastatin and moxalactam

The efficacy, safety and tolerance of imipenem/cilastatin and moxalactam were compared in a randomized trial in the United States involving 19 centers and 441 patients. Significantly more organisms were susceptible to imipenem than moxalactam. Although the bacteriological outcomes were similar, the clinical outcome was significantly better in the imipenem/cilastatin treatment group. The incidence of colonization and superinfection was similar in both groups. Moxalactam was less irritating at the site of injection than imipenem/cilastatin. The safety profiles were similar except for bleeding episodes in the moxalactam group.

Rapidly developing tolerance to acute exposures to anesthetic agents

Following the observation that mice manifest a characteristic withdrawal syndrome after an hour of exposure to nitrous oxide, the authors reasoned that there might be a very rapidly developing tolerance to nitrous oxide. Thus, they determined the inspired concentrations that cause loss of the righting reflex in mice (i.e, the ED50), in the presence of 1 atm of oxygen, of: 1) nitrous oxide alone; 2) cyclopropane alone; 3) nitrous oxide plus 13.6 atm helium; 4) ethylene plus 13.6 atm helium. In each instance the ED50 was determined after averages of 6,34 and 64 min of exposure to the anesthetic agents. For nitrous oxide alone the ED50 at 6 min was 1.18 +/- 0.049 atm, increasing to 1.39 +/- 0.061 atm at 64 min. For ethylene plus helium the ED50 increased from 1.21 +/- 0.033 atm at 6 min to 1.31 +/- 0.039 atm at 64 min, indicating the development of acute tolerance. Neither cyclopropane alone nor nitrous oxide plus helium caused acute tolerance. This absence of tolerance may have resulted from a slower development of an alveolar anesthetic concentration.

Halothane-epinephrine-induced cardiac arrhythmias and the role of heart rate

The authors previously showed that cyclopropane-epinephrine-induced bigeminal arrhythmias can best be explained by a re-entrant mechanism. They have now obtained evidence for reentry in bigeminal arrhythmias during infusions of epinephrine (.5-3 mug/kg/min) in dogs anesthetized with .8 per cent halothane. Both a critical level of blood pressure and a critical increase in heart rate were necessary for arrhythmias to be induced in any given animal. Artificial elevation of the blood pressure during infusion of a subthreshold dose of epinephrine could induce bigeminy, and the arrhythmia could be aborted by a sudden reduction of blood pressure. The heart rate accelerated approximately 40 beats/min prior to the onset of bigeminy, and atrial pacing at similarly increased rates during subthreshold infusion of epinephrine could induce bigeminy. Stimulation of the peripheral end of the cut right cervical vagus reduced heart rate and converted bigeminy to sinus rhythm. Bradycardia was not the sole mechanism of the vagal effect since conversion to sinus rhythm could also be achieved with more rapid stimulation of the vagus when the heart rate was maintained constant by atrial pacing. Under these conditions further acceleration of the heart rate could reinstate a bigeminal arrhythmia that was again sensitive to further increases in the frequency of vagal stimulation, and it is concluded that the vagus acts on the spread of the re-entrant impulse. This is best shown with cyclopropane anesthesia, because AV-nodal block occurs more easily with halothane. In addition, very brief periods of increased heart rate caused prolonged periods of bigeminy, which indicates that changes in heart rate may alter the electrophysiology of the halothane-sensitized myocardium to promote bigeminal arrhythmias by a re-entry mechanism.