Re-emerging poliomyelitis--is Australia's surveillance adequate?

In the past two years there has been a resurgence of polio with 21 previously polio-free countries importing wild poliovirus. Wild poliovirus importations into polio-free areas will continue to occur until endemic transmission is interrupted globally. Australia's acute flaccid paralysis (AFP) surveillance falls well short of the target of more than 80 per cent of AFP cases having two adequate stool specimens taken at least 24 hours apart within 14 days of onset for poliovirus examination. As most AFP cases are hospitalised, AFP should be immediately notifiable by hospitals to public health units or state or territory public health authorities to ensure appropriate follow up, including stool specimens.

An indirect (derivatization) and a direct HPLC method for the determination of the enantiomers of ketorolac in plasma.

An indirect and a direct HPLC method for the quantification of the (R) and (S) enantiomers of ketorolac are described here. The indirect method employs the chiral amine (+)-R-1-(1-naphthyl)ethylamine to form disastereomeric amides; separation of the disastereomeric derivates is achieved by normal-phase HPLC with a mobile phase of ethyl acetate-hexane. The direct method uses a C18 solid-phase extraction column to extract ketorolac enantiomers from plasma; the reconstituted extract is then injected onto an alpha 1-acid glycoprotein chiral column using a mobile phase of isopropanol-phosphate buffer (0.05 M; pH 5.5). Both methods are reproducible, accurate, and stereospecific, and both have equivalent quantification limits (0.02 microgram ml-1 of plasma for each enantiomer), ranges (0.02-2.0 micrograms per aliquot of plasma), precision (% relative standard deviations of < or = 10.5% and < or = 10.8% for (R)- and (S)-ketorolac respectively), and accuracy (mean recoveries of 88.4-110% and 90.1-110% for (R)- and (S)-ketorolac respectively). Results of analyses of clinical samples by the two methods showed excellent agreement (slope near 1.0 and coefficients of correlation between 0.9740 and 0.9864 for both enantiomers).

Single and multiple dose pharmacokinetics of ticlopidine in young and elderly subjects.

The pharmacokinetics of orally administered ticlopidine hydrochloride, a novel inhibitor of platelet aggregation, were determined both after a single dose and after 21 days of twice daily dosing in 12 young (mean 28.6 years) and 13 elderly (mean 69.5 years) subjects. Concentrations of unchanged ticlopidine in plasma were measured by g.l.c. After a single 250 mg dose of ticlopidine, the mean area under the curve, AUC (0-12 h) was 1.11 micrograms ml-1 h in young subjects and 2.04 micrograms ml-1 h in old subjects (P = 0.002). Mean values of t1/2,z in young and elderly subjects were 7.9 h and 12.6 h, respectively (P = 0.01). Steady state plasma drug concentrations were attained after 14 days of dosing with ticlopidine. After the final dose on day 21, AUC values in elderly subjects were 2-3 times those in young subjects (P less than 0.001). The plasma t1/2,z averaged 4.0 days for young subjects and 3.8 days for elderly subjects (P = 0.7). The longer t1/2,z and higher AUC values after multiple dosing probably reflect an increase in bioavailability of ticlopidine after repeated dosing, saturation of metabolism or insufficient analytical sensitivity to characterize the terminal elimination phase after single dose.

Rapid method to characterize lactococcal bacteriophage genomes.

We present a rapid method to isolate and analyze bacteriophage DNA. Cells are infected and phage replication is allowed to proceed normally for 30 to 60 min. Prior to DNA packaging and cell bursts, the infected cells (1 ml) are harvested and lysed by using a combination of lysozyme and sodium dodecyl sulfate treatments. The total DNA recovered is enriched for phage genomes, and restriction fragments of the phage DNA can be readily visualized on agarose gels. This method was used to grossly compare the genomes of nine lactococcal phages isolated from different cheese plants at different times. The method was also used to visualize the inhibitory effects of pTR2030-induced abortive infection on the replication of phage nck202.31 in its homologous host, Lactococcus lactis NCK203.

Development and characterization of a lyophilized dosage form of IL-1 beta.

The development and characterization of a lyophilized dosage form for recombinant Interleukin-1 beta is described. Included in the evaluation of the drug product are accelerated and long-term stability studies utilizing a number of biophysical techniques (reverse-phase HPLC, SDS-PAGE, isoelectric focusing and ELISA). Data collected with these methods were examined for correlations with biological activity assessments provided by an in-vitro cell culture system (mouse thymocyte proliferation). Results of these studies demonstrate that a lyophilized dosage form of Interleukin-1 beta can be prepared which retains its potency for at least 1 year when stored at ambient temperature. The analytical methodology used to assess the physicochemical integrity of the protein provided a sensitive and reproducible means of predicting changes in biological activity.

Ketorolac tromethamine pharmacokinetics and metabolism after intravenous, intramuscular, and oral administration in humans and animals.

In humans, ketorolac is completely bioavailable and its kinetics are linear. It is absorbed rapidly (half-life for absorption 3.8 min) after oral (fasting) and intramuscular administration; food delays but does not reduce its absorption. The drug is highly protein bound in humans (greater than 99%). The mean plasma elimination half-life is 5-6 hours, and ketorolac is not extensively distributed outside the vascular compartment (Vd beta 15 L). Virtually all of the drug-related material circulating in plasma is in the form of ketorolac (greater than 96%), with the only metabolite the pharmacologically inactive p-hydroxyketorolac (PHK). Humans excrete about 90% of the administered dose in urine. About 60% of drug-related material recovered from urine is ketorolac, about 12% is PHK, and 28% represents polar, glucuronide conjugates of ketorolac. The animal models in which ketorolac's metabolism and kinetics are most similar to those in humans are the mouse and monkey, respectively.

Inhibitors of cyclic AMP phosphodiesterase. 4. Synthesis and evaluation of potential prodrugs of lixazinone (N-cyclohexyl-N-methyl-4-[(1,2,3,5-tetrahydro-2- oxoimidazo[2,1-b]quinazolin-7-yl)-oxy]butyramide, RS-82856).

The cyclic AMP phosphodiesterase (cAMP PDE) inhibitor and cardiotonic agent lixazinone (N-cyclohexyl-N-methyl-4-[(1,2,3,5-tetrahydro-2- oxoimidazo[2,1-b]quinazolin-7-yl)oxy]butyramide, RS-82856, 1) and its acid and base addition salts were found to be insufficiently soluble in formulations suitable for intravenous administration. These results prompted an investigation into potential prodrugs with enhanced aqueous solubility designed to deliver 1 by three distinct mechanisms: (1) decarboxylation of alpha-carboxamides; (2) hydrolytic loss of a solubilizing N-1-(acyloxy)methyl or (N,N-dialkylamino)methyl moiety; or (3) intramolecular closure of a guanidino ester or amide. The target compounds were evaluated as delivery systems for 1 by three criteria: (1) chemical conversion rate to 1 under physiological conditions; (2) inhibition of type IV cAMP PDE at a fixed time point; and (3) in vivo inotropic activity in anesthetized dogs by both intravenous and oral administration. Release of 1 from 4a (series 1) was found to be too slow to be of value as a prodrug of 1, since decarboxylation could be induced only by strong acid, conditions under which hydrolytic ring opening was found to severely compete. Conversely, 1 was released too readily on exposure of (N,N-dialkylamino)methyl derivatives such as 8d (series 2) to physiological conditions, although no large increase in aqueous solubility was realized. Finally, both the physicochemical and in vitro studies indicated that ring closure of the guanidinium esters and amides 17a-k (series 3) to 1 was quantitative and pH- and time-dependent, suggesting the possibility of delivery of the open, water-soluble prodrug form, followed by closure to 1 in plasma. Detailed examination of these agents in vivo, however, demonstrated that only those compounds that rapidly cyclized to 1, as measured by plasma levels of 1, exhibited inotropic activity, indicating that the open prodrug form was not efficiently absorbed upon oral administration.

Selection of a derivative of the antiviral agent 9-[(1,3-dihydroxy-2-propoxy)-methyl]guanine (DHPG) with improved oral absorption.

Various diesters of 9-[(1,3-dihydroxy-2-propoxy)-methyl]guanine (DHPG) were screened in order to identify a derivative with improved oral absorption. The solubilities and dissolution rates decreased with increasing chain length and branching of the ester group. However, the dipropionate ester showed an anomalously faster dissolution rate. The rates of hydrolysis to DHPG in the presence of intestinal homogenates were found to increase with increasing carbon number for the straight-chain alkyl esters and decreased with branching. The shorter-chain alkyl esters were relatively more stable in intestinal homogenates than in liver homogenates. Therefore they may have a better membrane permeability than DHPG due to their intact ester group. The hydrolysis rates in human blood increased with increasing carbon number for the straight-chain alkyl esters. The dipropionate ester appeared to be the most promising derivative because of its rapid dissolution rate, slower hydrolysis in the intestine, and rapid conversion to DHPG in liver and blood.

Single intravenous dose and steady-state oral dose pharmacokinetics of nicardipine in healthy subjects.

Nicardipine HCl oral doses (10-40 mg) were administered sequentially to six healthy subjects. For each regimen the capsule dose was administered every 8 hours (q 8 h) for 3 days and the plasma profiles of nicardipine and its pyridine analogue (M5) were determined following the last dose on day 4. Steady-state plasma concentrations of nicardipine for each subject were fitted very well by the Michaelis-Menten equation. An intravenous tracer dose (0.885 mg nicardipine HCl) was administered simultaneously with the final oral dose on the fourth day of the 30 mg q 8 h regimen. The steady-state bioavailability of nicardipine was shown to be dose-dependent and averaged 19 per cent (10 mg), 22 per cent (20 mg), 28 per cent (30 mg), and 38 per cent (40 mg). Nicardipine undergoes linear first-pass metabolism to M5. Other metabolic pathways are responsible for the saturable first-pass metabolism observed for nicardipine.

Capillary column gas chromatographic method using electron-capture detection for the simultaneous determination of nicardipine and its pyridine metabolite II in plasma.

A rapid, specific and direct method based on capillary column gas chromatography with electron-capture detection is described for the simultaneous determination of nicardipine, a new calcium antagonist, and its pyridine metabolite II in human plasma. In this method, the nicardipine, its pyridine metabolite II and internal standard are extracted from the plasma and then partially purified by acid-base partitioning prior to the final injection onto the capillary column gas chromatograph for quantification by means of an electron-capture detector. The quantification limit of the method is 1 ng/ml of plasma for both nicardipine and its pyridine metabolite II. The coefficients of variation for nicardipine and the pyridine metabolite II at concentrations of 1-50 ng/ml are less than 7% and less than 9% (n = 4), respectively. The method has been validated against a previously developed high-performance liquid chromatographic method (sensitivity 5 ng/ml).

A high-performance liquid chromatographic method for the simultaneous determination of nicardipine and its pyridine metabolite II in plasma.

A rapid and specific method in which reverse-phase high-performance liquid chromatography (HPLC) with UV detection was used for the simultaneous determination of nicardipine and its pyridine metabolite II in human plasma is described. Nicardipine, its pyridine metabolite II, and the internal standard were extracted from plasma and partially purified by acid-base partitioning. Final purification and quantitation were achieved by HPLC by using a reverse-phase column and a UV detector (254 nm). The extraction efficiencies for nicardipine and its pyridine metabolite II from 1 mL of plasma were 77.4 and 81.1%, respectively. The sensitivity of the assay was 5 ng/mL for both nicardipine and its pyridine metabolite II, and the linear concentration range of the assay was 5-150 ng/mL for both compounds. The low coefficients of variation (less than or equal to 5%) for samples spiked with nicardipine and its pyridine metabolite II in this concentration range demonstrate good reliability and reproducibility of the assay. The HPLC procedure has been validated by comparison with a GC-electron-capture detection (ECD) procedure, which gives the combined concentration of nicardipine-its pyridine metabolite II (total) and with an HPLC/GC-ECD procedure, which gives the concentration of its pyridine metabolite II. All three methods, which were developed in our laboratory, were used to analyze nicardipine and its pyridine metabolite II in specimens of plasma from subjects treated with nicardipine hydrochloride. Good correlations were found for concentrations of nicardipine, its pyridine metabolite II, and nicardipine plus the metabolite determined by these three procedures. The HPLC procedure is suitable for use in pharmacokinetic studies following administration of nicardipine hydrochloride to humans.

Antibacterial activity of N-(beta-styryl) formamides related to tuberin.

A series of para-substituted N-(beta-styryl)formamides, analogues of tuberin (4a), has been prepared and assayed for antibacterial activity. The methylthio, ethoxy, and methyl analogues 4e, 4j, and 4t were about twice as active as tuberin against Mycobacterium phlei. Although tuberin lacks activity against Staphylococcus aureus, several of the analogues described were found to inhibit this organism. The phenyl group of tuberin is not a prerequisite for activity since analogues based on naphthyl or ferrocenyl groups were also active. A quantitative structure-activity relationship further implied that an aromatic group need not be present, suggesting the synthesis of the cyclohexyl and n-amyl analogues which were found to possess high activity.