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Biomedical subjects

G Peter

Publications and source records attributed to G Peter.

At least 19 recordsLinked to original sources
PubMed1992

Streptococcal pharyngitis: current therapy and criteria for evaluation of new agents.

Penicillin has been the recommended drug of choice in most cases of group A streptococcus (GAS) pharyngitis for nearly 40 years based on its efficacy in the prevention of acute rheumatic fever. Since trials of other drugs for the prevention of rheumatic fever are no longer feasible in the United States, eradication of GAS pharyngitis has become the surrogate for their evaluation. On the basis of this criterion, specific therapeutic regimens have been recommended, and numerous other drugs have gained approval as alternatives to penicillin. Current therapeutic issues include possible decreased efficacy of penicillin, timing of the initiation of therapy, and drugs of choice for patients whose treatment fails, who are chronic carriers, or who have frequent infections. Criteria for assessment of new drugs include clinical response, likelihood of prevention of rheumatic fever, rates of relapse and recurrent infection, and drug safety. The establishment of uniform guidelines and definitions of response for new drug evaluations by the Infectious Diseases Society of America should aid in the further assessment of new antibacterial agents as therapy for GAS pharyngitis. However, no data yet suggest that any of these drugs should replace penicillin as the drug of choice.

Anti-Bacterial Agents↗
PubMed1991

Metabolic fate of the novel antihypertensive drug naftopidil.

The metabolism of 14C-naftopidil ((R,S)-1-(2-methoxyphenyl)-1-piperazinyl-3- (1-naphthyl-oxy-2-propanol, CAS 57149-07-2) and the pharmacodynamic action of the metabolites was investigated. The metabolic pathway in rat, dog, mouse and man was qualitatively similar, with preference for the hydroxylation of the phenyl or naphthyl moiety of naftopidil [phenyl)hydroxy-metabolite, (naphthyl)hydroxy-metabolite). Cleavage of the parent compound and production of the propylene glycol metabolite was a further important reaction especially for rat and man. In all species investigated, demethylation of naftopidil occurs to a minor extent. O-desmethyl-naftopidil, (phenyl)hydroxy-naftopidil and (naphthyl)hydroxy-naftopidil were found to have similar affinities for the alpha 1-adrenoceptors as the parent compound (IC50)nmol/l): 433.0; 585.0; 52.7; respectively; naftopidil: 235.0). The naftopidil metabolites, like the parent compound showed no alpha 2- or beta-adrenoceptor affinity.

Animals↗
PubMed1991

Pharmacokinetic fate of the novel antihypertensive drug naftopidil.

The pharmacokinetics of naftopidil (R,S)-1-[4-(2-methoxyphenyl)-1-piperazinyl]-3-(1-naphthyloxy)-2 propanol, CAS 57149-07-2) was studied in rats and dogs using 14C-labeled drug in pharmacodynamically effective doses (oral doses: 5/10 mg/kg and intravenous doses: 1/2.5 mg/kg in rats/dogs, respectively). Naftopidil (14C) was rapidly and in high extent absorbed in rats and dogs after oral administration. The absolute bioavailability of the parent compound amounted to 9% in rats and indicates a high first pass effect to in part pharmacodynamically effective metabolites, as was shown in a previous paper. The parent compound and its 14C-metabolites were widely distributed into the periphery, more pronounced in the rat than in the dog, as indicated from comparison of the volumes of distribution and dose corrected Cmax- and AUC0-infinity-values in plasma. Elimination of radioactivity from plasma occurred in rat and dog in a similar rate. Tissue distribution studies in the rat showed highest peak-concentrations in the gastrointestinal (GI) tract (evaluated with contents) due to the predominant biliary elimination, followed by liver, adrenals, pituitary and Harderian glands, lungs, pancreas, kidneys, adipose tissue, bone marrow, aorta, thyroid and lymph nodes. Radioactivity was eliminated from most of the tissues within the first 168 h. Highest fractions of the dose were detected--apart from the GI-tract--in liver, muscle, skin, blood, and kidneys. After repeated administration to rats, accumulation of radioactivity in the 28 tissues examined did not exceed factor 9 or factor 5 in most of the tissues.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1990

Radioreceptor assay for the determination of alpha 1-adrenoceptor-binding material in rat plasma following single oral administration of naftopidil.

Naftopidil could be characterized by receptor binding studies as an alpha 1-adrenergic antagonist with a binding affinity constant (Ki) of 58.3 nmol/l. both enantiomers of naftopidil revealed similar values, indicating no stereoselective inhibition of 3H-prazosin-binding. An alpha 1-adrenergic radiorecptor assay (RRA) was developed to determine receptor-binding material (parent compound and active metabolites) in the plasma of rats following single oral administration of naftopidil (50 mg/kg). The results indicate a rapid absorption. At the first sampling time (0.5 h) maximum concentration of receptor-binding material was measured. Terminal half-life was calculated with 16.7 h.

Administration, Oral↗
PubMed1979

Synthesis and preliminary antitumor evaluation of 4-(SR)-sulfido-cyclophosphamides.

Crystalline 4-(SR)-sulfidocyclophosphamides, sulfido derivatives of activated cyclophosphamide (4-hydroxycyclophosphamide), were synthesized by ozonation of cyclophosphamide and reaction of the intermediate 4-hydroxycyclophosphamide with various thiols (HSR). The products were characterized by elemental analysis, 1H NMR and IR spectroscopy, and mass spectrometry. 1H NMR and polarimetric analysis demonstrated that they consist of racemic cis-isomers that are stable in the crystalline state at room temperature. In aqueous solution these derivatives are hydrolyzed to 4-hydroxycyclophosphamide and the corresponding thiol, with half-lives ranging between 4 and 17 min at 37 degrees C and pH 7. The cytotoxicity of 4-(S-ethyl)- and 4-(S-ethanol)-sulfidocyclophosphamide against Yoshida sarcoma ascites cells and the toxicity in rats were found to be practically identical with those of activated cyclophosphamide. A preliminary evaluation of the curative effect after a single IV injection of 4-(S-ethane)- and 4-(S-ethanol)-sulfidocyclophosphamide in rats bearing Yoshida ascites sarcoma or of 4-(S-ethanol)-sulfidocyclophosphamide in nu/nu mice bearing human breast carcinoma xenografts suggested that these sulfido derivatives possess the same oncostatic efficacy as activated cyclophosphamide itself.

Animals↗
PubMed1979

Correlations between age-dependent protein and lipid concentrations in plasma and platelet functions in children.

The correlations between the levels of various plasma proteins and lipids and platelet function on glass and platelet factor 3 (PF 3)-availability in children of different age-groups were investigated. Several statistically significant positive and some significant negative correlations were found. Although conclusions based solely on such correlations should be considered with reservation, in our opinion the following factors should stimulate platelet function: prealbumin (adhesion and PF 3-availability in all age-groups, aggregation--specifically for children in puberty); alpha 1-antitrypsin (PF 3-availability); alpha 2-macroglobulin (platelet spreading capacity, PF 3-availability); plasminogen (platelet adhesion and aggregation--specifically for boys in puberty); caeruloplasmin (number of "free adhering platelets" spreading capacity); lysolecithin and lecithin (time-dependent increase of spontaneous platelet adhesion and aggregation, PF 3-availability); and free fatty acids (FFA) (PF 3-availability). Plasminogen and complement component C'3 show a negative relationship to the time-dependent increase of spontaneous platelet adhesiveness and aggregability in platelet-rich plasma.

Adolescent↗
PubMed1979

Vancomycin treatment of cerebrospinal fluid shunt infections. Report of two cases.

The successful use of vancomycin is reported in two children with shunt infections due to Staphylococcus epidermidis which failed to respond to shunt removal. The previously reported experience with this drug is reviewed. The use of vancomycin should be considered in cases of shunt infections due to susceptible microorganisms and refractory to other therapeutic measures.

Cerebrospinal Fluid Shunts↗
PubMed1978

Demographic factors in the epidemiology of hemophilus influenzae meningitis in young children.

To determine the effect of various demographic factors on the incidence of Hemophilus influenzae, type b meningitis, Rhode Island residents with H. influenzae in 1970-1974 were identified by review of data from the State Department of Health, a private health care research organization, death certificates, and hospital bacteriology laboratories. Of the 108 cases of H. influenzae, 99 (92%) occurred in children under five years of age. The disease incidence among black children under five (103.6/100,000/annum) was significantly (P less than 0.0005) higher than that among white children (23.9/100,000/annum). By eliminating the 29 of 185 census tracts in which the total population was greater than 5% black, disease incidence was studied in a virtually monoracial population. In these white census tracts, in which the population was 99.2% white, the occurrence of H. influenzae was not related to family income, education, number of household members, population density, or rate of hospitalization. These findings confirm the increased incidence of H. influenzae in blacks and indicate that socioeconomic factors do not affect the incidence of the disease in white children.

Black or African American↗