Edwin M. Oden

Low incidence of serum neutralizing factors in patients receiving recombinant alfa-2b interferon (intron a)

The development of serum neutralizing factors against recombinant alfa-2b interferon (Intron A) was reviewed in a large clinical experience. In 537 patients receiving systemic therapy, neutralizing factors developed in only 13 (2.4 percent). In 1,326 patients who received intranasal administration and 154 with intralesional administration, the incidence was less than 1 percent. Patients in whom antibody developed had no predisposing characteristics that could be identified, no particular types of patients with cancer had a high rate of neutralizing factors, and two of 10 patients with cancer in whom neutralizing factor developed were still able to show clinical responses. In patients in whom neutralizing factor was present, there was no discernible difference in the incidence or severity of interferon side effects as compared with patients who had no demonstrable neutralizing factor levels. This form of recombinant alpha-2 interferon appears to have a very low antigenic potential.

Pharmacokinetics of Interferon α-2b in Healthy Volunteers

In a three‐way crossover design, 12 healthy male volunteers received 5 × 106 IU/m2 body surface area interferon α‐2b(IFN α‐2b) by intravenous (IV) infusion over 30 minutes, intramuscular (IM) injections, and subcutaneous (SC) injections. Blood and urine samples were collected at specified times, and analysis of IFN α‐2b concentrations was performed by immunoradiometric assay. “Flulike” symptoms were the most frequently reported adverse experiences and were independent of the route of administration. After a 30‐minute IV infusion, IFN α‐2b disappeared rapidly from serum, with distribution and elimination phase half‐lives of 0.1 hour and 1.7 hours, respectively. Interferon α‐2b was absorbed slowly after IM and SC administration, with similar absorption half‐lives of 5.8 and 5.5 hours, respectively. The observed maximal concentrations after IM and SC administration were 42.1 IU/mL at six hours and 45.8 IU/mL at eight hours, respectively. Interferon α‐2b was eliminated with half‐lives of 2.2 hours after IM administration and 2.9 hours after SC administration. The areas under the serum concentration‐time curves for the SC and IM doses were higher than those obtained for the IV infusion. Measurable amounts of IFN α‐2b were not found in urine regardless of the route of administration.

A radioimmunologic technique to screen for antibodies to α-2 interferon

Abstract A radioimmunologic technique has been developed to screen sera of persons receiving human α-2 interferon for the presence of specific antibodies to α-2 interferon. The method is sensitive and easy to perform. It tests the ability of the sera to neutralize α-2 interferon and prevent the interferon from being detected by an immunoradiometric assay. The results obtained using this technique are in good agreement with an anti-viral, cytopathic effect assay. Using the immunological technique, the sera from more than 1000 individuals who had received different doses of α-2 interferon by one or more of various routes of administration were tested. Twenty-five sera representing 14 individuals gave a positive or possibly positive reaction in the assay. Three of the 14 individuals were positive prior to receipt of α-2 interferon. Another 3 had reverted to negative when tested a few months later. Of the remaining 8, only 4 developed titers greater than 100 neutralizing units/ml. Hence approximately 1% of the α-2 interferon recipients may have produced neutralizing antibodies.

High-pressure liquid chromatographic method for determination of rosaramicin in humans.

A high-pressure liquid chromatographic method has been developed for the quantitative determination of rosaramicin in serum. This procedure involves addition of an internal standard, adjustment to alkaline pH, treatment with potassium carbonate, ether extraction, and a reverse-phase column separation with acetonitrile-acetate buffer mixture as the mobile phase. This technique produces a good linear relationship between the peak height ratio and the rosaramicin concentration. In addition, this method has proven to be quite specific for rosaramicin, since many of its derivatives tested do not interfere with the assay. The method is accurate and reproducible with a sensitivity of about 0.01 microgram of rosaramicin per ml of serum. It may be useful in monitoring drug levels in serum of patients and also for the pharmacokinetic studies of the drug in humans.

New Polyene Antifungal Antibiotic Produced by a Species of Actinoplanes

A new species of Actinoplanes, which has been deposited with the designation NRRL 5325 at the Northern Utilization Research and Development Division of the U. S. Department of Agriculture, produces a polyene antifungal complex designated as Sch 16656. The complex, consisting of one major and three minor components, is isolated from the fermentation broth by a solvent extraction procedure and purified by precipitation methods. The major component is a heptaene and is highly active in vitro and in vivo against Candida albicans. It is active also against strains of Torulopsis and is significantly more potent orally than candicidin in mice against Candida infections. Images

Biological Activity of Sch 14342, an Aminoglycoside Antibiotic Coproduced in the Gentamicin Fermentation

Sch 14342 is an aminoglycoside antibiotic coproduced as a minor component in the gentamicin fermentation. Sch 14342 was found to have the same antibacterial spectrum as gentamicin in vitro and in vivo, and was approximately one-third as active in mouse protection tests. Sch 14342 relative to gentamicin was one-third as toxic in acute tests in mice, one-eighth as toxic in renal toxicity tests in dogs, and an estimated one-tenth as toxic in cat ataxia tests. Sch 14342 possesses a significantly improved therapeutic index relative to gentamicin with reference to ataxia potential and renal toxicity.

4.16 – GENTAMICIN

Publisher Summary This chapter focuses on gentamicin, which is the first significant antibiotic isolated from the genus Micromonospora. One assay for detection of low levels of the antibiotic in serum, utilizes Bacillus subtilis; two methods for use with higher levels of gentamicin use either Staphylococcus aureus (S. aureus) or Staphylococcus epidermidis (S. epidermidis). Gentamicin standard contains mixed sulfates assaying 641 μg /mg when dried. The working standard needs to be dried at 110° at a pressure of 5 mm of mercury or less for 3 h. Then, the dried standard is to be dissolved in sufficient 0.1 M potassium phosphate buffer, pH 8.0, to give a stock solution of convenient concentration of gentamicin base. The linear response of the S. aureus assay has a range of 0.5–6.0 μg/ml, and the S. epidermidis method a range of 0.05 to 0.6 μg/ml. One requires diluting the standard solution in 0.1 M potassium phosphate buffer, pH 8.0, to give a standard curve with the doses evenly spaced on the logarithmic scale.

Method for Qualitative Determination of 2-Deoxystreptamine

We have developed a qualitative method to assay for the presence of 2-deoxystreptamine in hydrolysates of crude aminoglycoside preparations using a 2-deoxystreptamine-requiring idiotrophic mutant. The assay involves (i) incubation of a 2-deoxystreptamine-requiring mutant with 1 mg of a hydrolyzed preparation from a crude unknown antibiotic mixture per ml, and (ii) examination of the resultant incubation mixture for production of antibiotic(s) by disk assay.

High-pressure liquid chromatographic method for determination of Sch 29482 in human serum.

A high-pressure liquid chromatographic method was developed for quantitative determination in human serum of a new penem antibiotic known as Sch 29482 (5R,6S,8R-2-ethylthio-6(1-hydroxyethyl)penem-3-carboxylic acid). The method involves serum extraction at an acid pH with ether, followed by separation on a reverse-phase column and UV light detection at 254 nm. This technique produced a good linear relationship between the peak height ratio and the Sch 29482 concentration, which ranged from 0.09 to 35.64 micrograms/ml. In addition, this procedure proved to be quite specific for Sch 29482, since all beta-lactam antibiotics tested did not interfere with the assay. For high concentrations (greater than 0.5 micrograms/ml), the mean values obtained from the high-pressure liquid chromatographic method correlated very well (r = 0.997) with those obtained from a microbiological assay. This method is accurate and reproducible, with a sensitivity of about 0.09 micrograms per ml of serum. It is useful for monitoring serum drug levels in animals and humans and can also be used for drug pharmacokinetic studies in humans.

4.27 – TOLNAFTATE

Publisher Summary This chapter reviews tolnaftate, a potent topical antifungal agent, which demonstrates unique selective antifungal activity against Trichophyton sp. and Microsporum sp. Tolnaftate lends itself to analysis by a spectrophotometric assay and by a microbiological plate assay. Tolnaftate has an ultraviolet absorption peak at 260 nm. The microbiological assay of tolnaftate is an agar diffusion method using Aspergillus niger (A. niger) ATCC 10535 as the test organism. The inoculum needs to be prepared by growing A. niger in a Roux bottle containing approximately 300 ml of Sabouraud agar. Next step involves incubating the inoculated Roux bottle at 28° for 7 days. The inoculum should be prepared by growing A. niger in a Roux bottle containing approximately 300 ml of Sabouraud agar. Incubate the inoculated Roux bottle at 28° for 7 days. The stock solution containing 100 μg/ml in 0.1 M potassium phosphate buffer, pH 6.0 should be diluted to give a standard curve of 0.64, 0.80, 1.00, 1.25, and 1.56 μg/ml.