Vancomycin-associated nephrotoxicity: grave concern or death by character assassination?

Vancomycin-associated nephrotoxicity was reported in 0% to 5% of patients in the 1980s. This has been confirmed by numerous clinical trials comparing novel anti-methicillin-resistant Staphylococcus aureus agents with vancomycin at the Food and Drug Administration-approved dosage of 1 g every 12 hours. Treatment failures of vancomycin in patients with methicillin-resistant S. aureus infections have been reported despite in vitro susceptibility. These failures have led to the use of vancomycin doses higher than those approved by the Food and Drug Administration. Higher doses are being administered to achieve goal vancomycin trough concentrations of 10 to 20 microg/mL recommended by several clinical practice guidelines endorsed by the Infectious Diseases Society of America. Recent studies suggest that increased rates of nephrotoxicity are associated with aggressive vancomycin dosing. These increased rates are confounded by concomitant nephrotoxins, renal insufficiency, or changing hemodynamics. These studies also have demonstrated that vancomycin's nephrotoxicity risk is minimal in patients without risk factors for nephrotoxicity. Clinicians unwilling to dose vancomycin in accordance with clinical practice guidelines should use an alternative agent because inadequate dosing increases the likelihood of selecting heteroresistant methicillin-resistant S. aureus isolates.

A formalized teaching, practice, and research partnership with the Veterans Affairs North Texas Health Care System: a model for advancing academic partnerships

In 1999, the Texas Tech University Health Sciences Center School of Pharmacy expanded its Dallas/Fort Worth presence by creating a regional campus for pharmacy students in their third and fourth years (P3 and P4 years) of the program. This expansion was driven by the need for additional practice sites. The VANTHCS was an obvious choice for the school due to the similarity of missions for clinical practice, education, and research. The VANTHCS and pharmacy school renovated a 4,000 square foot building, which includes classrooms, conference rooms, a student lounge, and faculty offices (expanded to 8,000 square feet in 2003). To date, the school has invested $1 million in the building. From a practice perspective, VANTHCS purchases faculty professional services from the school to augment its clinical specialist staff. These professional practice contracts provide VANTHCS with 12 additional clinical pharmacy specialists serving 50% of their time in multiple specialty areas. The collaboration has also allowed for expansion of clinical teaching, benefitting both institutions. In addition to the pharmacy student interns on P3 and P4 practice experiences, the collaboration allows for 8 to 10 postgraduate pharmacy residents to train with VANTHCS clinical specialists and school faculty members each year. The VANTHCS/pharmacy school collaboration has clearly enhanced the ability of both institutions to exceed their teaching, research, and practice goals in a cost-effective manner.

Treatment of active pulmonary tuberculosis in adults: current standards and recent advances. Insights from the Society of Infectious Diseases Pharmacists

Tuberculosis is a global pandemic, with 9 million new cases of the disease and approximately 2 million deaths each year. More than 98% of patients treated for tuberculosis in the United States between 1993 and 2007 had drug-susceptible strains. The standard treatment regimen for drug-susceptible tuberculosis has not changed in decades and was developed on the basis of empiric observations of different treatment regimens. Only recently has the veracity of the scientific basis for standard therapy been examined. The backbone of therapy is still isoniazid, rifampin, and pyrazinamide, although fluoroquinolones are being investigated as a replacement for isoniazid. Recent population pharmacokinetic studies have demonstrated the importance of individualized dosing of isoniazid, pyrazinamide, and rifampin. Isoniazid serum clearance differs depending on the patient's number of N-acetyltransferase 2 gene *4 (NAT2*4) alleles. Pyrazinamide serum clearance has been shown to increase with increases in body weight. Rifampin's volume of distribution, clearance, and absorption have wide between-patient and within-patient variability. Microbial pharmacokinetic-pharmacodynamic (PK-PD) indexes and targets to optimize microbial killing and minimize resistance have been identified for rifampin, isoniazid, pyrazinamide, and the fluoroquinolones. These PK-PD indexes suggest that different doses and dosing schedules than those currently recommended could optimize therapy and perhaps shorten duration of therapy. Efflux pump inhibition is also being investigated to enhance first-line antituberculosis drug therapy. Comorbid conditions such as diabetes mellitus and genetically determined iron overload syndromes have been associated with significantly worse patient outcomes. Therapy for these and other patient groups needs further improvement. These patient factors, the covariates for pharmacokinetic variability, and PK-PD factors suggest the need to individualize therapy for patients with tuberculosis in order to optimize outcomes and reduce the duration of therapy.

Multicenter evaluation of vancomycin dosing: emphasis on obesity

BACKGROUND

There is a paucity of data available regarding the dosing of antimicrobials in obesity. However, data are available demonstrating that vancomycin should be dosed on the basis of actual body weight.

METHODS

This study was conducted at 2 tertiary care medical centers that did not have pharmacy-guided vancomycin dosing programs or other institutional vancomycin dosing policies or protocols. Patients who received vancomycin between July 1, 2003, and June 30, 2006, were stratified by body mass index and randomly selected from the computer-generated queries. Patients >or=18 years of age with a creatinine clearance of at least 60 mL/min who received vancomycin for at least 36 hours were included.

RESULTS

Data were collected on a random sampling of 421 patients, stratified by body mass index, who met the inclusion criteria. Most patients in each body mass index category received a fixed dose of vancomycin 2 g daily divided into 2 doses (underweight 82%, normal weight 90%, overweight 86%, and obese 91%). Adequate initial dosing (>or=10 mg/kg/dose) was achieved for 100% of underweight, 99% of normal weight, 93.9% of overweight, and 27.7% of obese patients (P < .0001). Ninety-seven percent of underweight, 46% of normal weight, 1% of overweight, and 0.6% of obese patients received >or=15 mg/kg/dose recommended by several Infectious Diseases Society of America guidelines. Pharmacists also failed to correct inadequate dosing because only 3.3% of patients receiving less than 10 mg/kg/dose had their regimen changed in the first 24 hours of therapy.

CONCLUSION

In this multicenter pilot study, obese patients routinely received inadequate empiric vancomycin using a lenient assessment of dosing. Greater efforts should be undertaken to ensure patients receive weight-based dosing because inadequate dosing can lead to subtherapeutic concentrations and potentially worse clinical outcomes.

Impact of Inadequate Empiric Antimicrobial Therapy on Clinical Outcomes of Patients With Escherichia coli or Klebsiella Species Bacteremia

This study was conducted to evaluate the effect of inadequate empiric antimicrobial therapy (IEAT) on mortality of patients with Escherichia coli or Klebsiella species bacteremia. Patients with E coli or Klebsiella species bacteremia were retrospectively analyzed to determine the effect of IEAT on 14-day mortality. IEAT of bacteremia was defined as administration of an antimicrobial agent to which the microorganism responsible for the bacteremia was resistant. IEAT was significantly associated with central venous catheter placement, Klebsiella species, and antimicrobial resistance among the 135 patients with E coli or Klebsiella species bacteremia (110 adequate, 25 inadequate). IEAT significantly increased 14-day mortality (32% vs 19%; P = .019). The increased 14-day mortality associated with IEAT was consistent among patients infected with E coli (33% vs 11%) or Klebsiella species (31% vs 15%). Independent risk factors for 14-day mortality in the multivariate analysis included Acute Physiology and Chronic Health Evaluation II (APACHE II) score (odds ratio [OR] 1.16; 95% confidence interval [CI] = 1.07-1.27), IEAT (OR 9.4; 95% CI = 1.36-65.14), and initial imipenem therapy (OR 20.66; 95% CI = 1.48-287.74). Of the 6 patients receiving empiric imipenem/cilastatin, 3 had APACHE II scores ≥ 30 (all 3 of these patients died). The 14-day mortality rate was similar for patients who received IEAT, regardless of whether their therapy was changed (32%) or not (33%). Based on these results and previous studies, greater efforts should be made to identify patients at risk for resistant pathogens before initiating antimicrobial therapy.

Simulated Comparison of the Pharmacodynamics of Ciprofloxacin and Levofloxacin Against Pseudomonas aeruginosa Using Pharmacokinetic Data from Healthy Volunteers and 2002 Minimum Inhibitory Concentration Data

BACKGROUND

Until the 2002 approval of levofloxacin 750 mg QD, ciprofloxacin was the fluoroquinolone of choice against Pseudomonas aeruginosa infections.

OBJECTIVE

This study evaluated the AUC:MIC ratios for ciprofloxacin 400 mg BID and TID and levofloxacin 750 mg QD, all administered intravenously, against P. aeruginosa using a Monte Carlo simulation.

METHODS

Pharmacokinetic data for ciprofloxacin and levofloxacin and 2002 MIC distributions against P. aeruginosa were obtained from studies in healthy volunteers published in the peer-reviewed literature. Pharmacokinetic studies of each agent were identified by separate MEDLINE searches combining the MeSH heading pharmacokinetics with the generic name of the antimicrobial. Only human studies published in English between 1990 and 2001 were included. Included studies also had to meet 3 minimum criteria: evaluation of clinically relevant dosing regimens, use of rigorous study methods, and provision of mean (SD) values for the pharmacokinetic parameters of interest. When multiple studies met these criteria, a single study was selected for each antimicrobial regimen. Pharmacodynamic analysis was performed using a Monte Carlo simulation of 10,000 patients by integrating the pharmacokinetic parameters, their variability, and 2002 MIC distributions for each antimicrobial regimen. The probability of target attainment was determined for each regimen for an AUC:MIC ratio from 0 to 300. A > or =90% probability of target attainment was considered satisfactory.

RESULTS

For ciprofloxacin 400 mg TID and levofloxacin 750 mg QD, the AUC:MIC ratio at the corresponding 2002 Clinical Laboratory Standards Institute break points of 1 and 2 microg/mL were 33 and 34, respectively. The probabilities of target attainment for a free AUC:MIC ratio >90 (equivalent to a total AUC:MIC ratio > or =125) were 47% for ciprofloxacin 400 mg BID, 54% for ciprofloxacin 400 mg TID, and 48% for levofloxacin 750 mg QD.

CONCLUSION

When pharmacokinetic data from healthy volunteers and 2002 MIC data were used, none of the simulated fluoroquinolone regimens achieved a high likelihood of target attainment against P. aeruginosa.

Gatifloxacin-Induced Hyperglycemia: A Review of 4 Cases and the Literature

Gatifloxacin, a broad-spectrum fluoroquinolone, has recently been voluntarily withdrawn by Bristol-Myers Squibb from the market secondary to dysglycemic events associated with this agent. Risk factors for this adverse event include diabetes and those who are elderly (65 years of age or older), have renal insufficiency, or take glucose altering medications. The mechanism for this adverse reaction is not fully understood. However, it is theorized that there is an association between accumulation of gatifloxacin (particularly in elderly patients or those with renal insufficiency) and dysglycemic events with gatifloxacin. A review of the literature found 13 reported cases of hyperglycemia induced by gatifloxacin and 2 clinical trials evaluating gatifloxacin's association with hyperglycemia. Similarly to other reported cases, the authors' 4 outpatients were initiated on gatifloxacin therapy and subsequently had developed hyperglycemia during gatifloxacin therapy. Prior to the multiple observations of dysglycemias associated with gatifloxacin, this medication was widely used and thought to have an excellent safety profile. Hence, clinicians should be vigilant and exercise caution with newly approved medications.

Atazanavir for the treatment of human immunodeficiency virus infection

Atazanavir is the first once-daily protease inhibitor for the treatment of human immunodeficiency virus type 1 infection and should be used only in combination therapy, as part of a highly active antiretroviral therapy (HAART) regimen. In addition to being the most potent protease inhibitor in vitro, atazanavir has a distinct cross-resistance profile that does not confer resistance to other protease inhibitors. However, resistance to other protease inhibitors often confers clinically relevant resistance to atazanavir. Currently, atazanavir is not a preferred protease inhibitor for initial HAART regimens. In treatment-naive patients, atazanavir can be given as 400 mg/day. However, atazanavir should be pharmacologically boosted with ritonavir in treatment-experienced patients or when coadministered with either tenofovir or efavirenz. Patients who receive atazanavir experience similar rates of adverse events compared with patients receiving comparator regimens. An exception is an increased risk of asymptomatic hyperbilirubinemia, which is due to competitive inhibition of uridine diphosphate-glucuronosyltransferase 1A1. Although hyperbilirubinemia is a common adverse drug reaction of atazanavir therapy (22-47%), fewer than 2% of patients discontinue atazanavir therapy because of this adverse effect. Common adverse effects reported with atazanavir include infection, nausea, vomiting, diarrhea, abdominal pain, headache, peripheral neuropathy, and rash. Of significance, fewer abnormalities have been observed in plasma lipid profiles in patients treated with atazanavir compared with other protease inhibitor-containing regimens. As with other protease inhibitors, atazanavir is also a substrate and moderate inhibitor of the cytochrome P450 (CYP) system, in particular CYP3A4 and CYP2C9. Clinically significant drug interactions include (but are not limited to) antacids, proton pump inhibitors, histamine type 2 receptor antagonists, tenofovir, diltiazem, irinotecan, simvastatin, lovastatin, St. John's wort, and warfarin. We conclude that atazanavir is a distinctively characteristic protease inhibitor owing to its in vitro potency, once-daily dosing, distinct initial resistance pattern, and infrequent association with metabolic abnormalities.

In vitro killing of parenteral beta-lactams against standard and high inocula of extended-spectrum beta-lactamase and non-ESBL producing Klebsiella pneumoniae

Minimum inhibitory concentrations and time-kill curves were performed against 8 Klebsiella pneumoniae (4 non-extended-spectrum beta-lactamase[ESBL] and 4 ESBL) for piperacillin/tazobactam (40/5 microg/mL), cefepime (20 microg/mL), and meropenem (4 microg/mL) by using a standard and high inocula. Imipenem was evaluated only at the standard inoculum for the non-ESBL and ESBL isolates. Samples were withdrawn at 7 predetermined time-points over 24 hours and plated on trypticase soy agar plates. Minimum inhibitory concentrations were: piperacillin/tazobactam 4 to 8 microg/mL (ESBL and non-ESBL), cefepime 1 to 2 microg/mL (ESBL) and 0.06 to 0.125 microg/mL (non-ESBL), imipenem 0.125 to 0.25 microg/mL (ESBL and non-ESBL), and meropenem 0.03 to 0.06 microg/mL (ESBL and non-ESBL). Each antibiotic reached and maintained bactericidal killing (> or =3 log killing) for 24 hours against all non-ESBL isolates for both the standard and high inoculum. Cefepime, imipenem, and meropenem showed the same bactericidal activity against each ESBL isolate at the standard inoculum, whereas piperacillin/tazobactam showed bactericidal killing against only 1 ESBL isolate. At the high inoculum, cefepime and piperacillin/tazobactam were unable to maintain bactericidal activity against any of the ESBL isolates. Only meropenem was able to maintain bactericidal killing over 24 hours against the ESBL isolates at the high inoculum. In summary, meropenem and imipenem maintained bactericidal activity against non-ESBL and ESBL K. pneumoniae irrespective of the inoculum size. While piperacillin/tazobactam and cefepime are bactericidal against non-ESBL K. pneumoniae, their activity against ESBL K. pneumoniae is limited and based on the size of the inoculum. Until more data are available, piperacillin/tazobactam and cefepime should not be used for the treatment of ESBL K. pneumoniae.

In vitro activity of parenteral Beta-lactams, levofloxacin and tobramycin alone or in combination against extended-spectrum Beta-lactamase producing Klebsiella pneumoniae

MICs and time-kill studies were performed for four clinical isolates of extended-spectrum Beta-lactamase (ESBL)-producing Klebsiella pneumoniae. MICs (mg/L) were: piperacillin/tazobactam 8, cefepime 1-2, meropenem 0.03-0.06, levofloxacin 0.5-8 and tobramycin 0.25-32. For monotherapy, only meropenem maintained bactericidal activity over the 24 h for all isolates. Levofloxacin and tobramycin maintained bactericidal activity against the isolate susceptible to each drug. Piperacillin/tazobactam and cefepime did not maintain bactericidal activity against any isolate. Combination therapy with piperacillin/tazobactam or cefepime combined with levofloxacin or tobramycin were able to provide dramatic killing against ESBL K. pneumoniae, but did not always maintain bactericidal activity. Future studies should evaluate different antimicrobial combinations against pathogens producing specific ESBL enzymes to define their utility as an alternative to carbapenems.

Clinical and microbiologic analysis of a hospital's extended-spectrum beta-lactamase-producing isolates over a 2-year period

STUDY OBJECTIVE

To evaluate the microbiologic and clinical outcomes of patients with extended-spectrum beta-lactamase (ESBL)-producing isolates over a 2-year period.

DESIGN

Retrospective analysis.

SETTING

Tertiary care teaching hospital.

PATIENTS

Twenty-one patients with cultures of confirmed ESBL-producing Escherichia coli, Klebsiella pneumoniae, or Klebsiella oxytoca.

MEASUREMENTS AND MAIN RESULTS

Antimicrobial susceptibilities of piperacillin-tazobactam, cefotetan, carbapenems, aminoglycosides, fluoroquinolones, trimethoprim-sulfamethoxazole, and nitrofurantoin (nitrofurantoin for urinary isolates only) of confirmed ESBL producers at our institution were determined, as well as clinical outcomes of patients with ESBL-producing isolates. Microbiologic and medical records were reviewed for patient sex and age, antimicrobial susceptibilities, antimicrobial therapy, and clinical and microbiologic outcomes. From January 2000-December 2001, 31 isolates were confirmed as ESBL producers (6 E. coli, 11 K. pneumoniae, and 14 K. oxytoca). A statistically significant increase occurred over the 2-year period from 9 (0.6%) of 1414 isolates in 2000 to 22 (1.8%) of 1218 isolates in 2001 (p = 0.0055). All isolates were susceptible to carbapenems, and more than 88% were susceptible to amikacin, cefotetan, or nitrofurantoin. Less than 70% of isolates were susceptible to gentamicin, fluoroquinolones, piperacillin-tazobactam, or trimethoprim-sulfamethoxazole. All patients treated with a carbapenem experienced clinical cure. Piperacillin-tazobactam alone and in combination resulted in an overall clinical cure rate of 55%, with a 50% cure rate for isolates susceptible to piperacillin-tazobactam. All patients in whom antibiotic therapy failed had been treated with piperacillin-tazobactam or cefepime, either alone or in combination with a fluoroquinolone.

CONCLUSION

Carbapenems remain the treatment of choice for ESBL-producing pathogens. Piperacillin-tazobactam and cefepime should not be routinely administered for the treatment of these organisms.

In vitro evaluation of the activity of two doses of Levofloxacin alone and in combination with other agents against Pseudomonas aeruginosa

P. aeruginosa is one of the most difficult to treat pathogens that generally requires combination therapy to prevent the development of resistance. This study evaluated the in vitro activity of two concentrations of levofloxacin (modeled for the 500 mg and 750 mg daily dose) in combination with ceftazidime, cefepime, piperacillin/tazobactam, imipenem, and tobramycin against P. aeruginosa. MICs and time-kill studies were performed against 12 non-duplicate clinical isolates of P. aeruginosa. The percent susceptible for levofloxacin, ceftazidime, cefepime, piperacillin/tazobactam, imipenem, and tobramycin were 67%, 58%, 58%, 67%, 75%, and 100%, respectively. Tobramycin was the most active single agent, killing and maintaining > or =99.9% killing over a 24 h period against all isolates. Levofloxacin 4 microg/mL(750 mg/day) alone reached 99.9% killing and maintain this killing over the time period more often than levofloxacin 2 microg/mL (500 mg/day). No combination was antagonistic and all combinations with tobramycin were indifferent. Overall, levofloxacin 2 microg/mL plus a beta-lactam was synergistic (65%) more often than levofloxacin 4 microg/mL combinations (46%). This was not unexpected due to the increased activity of levofloxacin 4 microg/mL. However, levofloxacin 4 microg/mL combinations maintained a > or =99.9% killing over the entire 24 h period more often than levofloxacin 2 microg/mL combinations (94% vs 83%). The findings from this work suggest that levofloxacin 750 mg/day in combination with another agent active against P. aeruginosa may prove to be clinically beneficial and superior to combinations using lower doses of levofloxacin. In vivo studies are needed to evaluate the clinical significance of these findings.

Synthesis and structure-activity relationships of benzophenone hydrazone derivatives with insecticidal activity

A broad range of benzophenone hydrazone derivatives was prepared and tested against selected chewing insect pests, allowing the analysis of structure-activity relationships. Good activity was found only when the aromatic rings were substituted at the 4-positions with an halogen atom and a triflate or perhaloalkoxy group. In contrast, a number of substituents on the hydrazone part led to active compounds, the best results being achieved with acyl-type substituents. The excellent laboratory and greenhouse activity of the best representatives was confirmed in semi-field trials against Spodoptera littoralis.

Phosphinic acid analogues of GABA. 1. New potent and selective GABAB agonists

The antispastic agent and muscle relaxant baclofen 1 is a potent and selective agonist for bicuculline-insensitive GABAB receptors. For many years efforts to obtain superior GABAB agonists were unsuccessful. We describe the syntheses and biological properties of two new series of GABAB agonists, the best compounds of which are more potent than baclofen in vitro and in vivo. They were obtained by replacing the carboxylic acid group of GABA or baclofen derivatives with either the phosphinic acid or the methylphosphinic acid residue. Surprisingly, ethyl- and higher alkylphosphinic acid derivatives of GABA yielded novel GABAB antagonists, which are described in part 2 of this series. Structure-activity relationships of the novel GABAB agonists are discussed with respect to their affinities to GABAB receptors as well as to their effects in many functional tests in vitro and in vivo providing new muscle relaxant drugs with significantly improved side effect profiles.

Phosphinic acid analogues of GABA. 2. Selective, orally active GABAB antagonists

In 1987, 25 years after the synthesis of the potent and selective GABAB agonist baclofen (1), Kerr et al. described the first GABAB antagonist phaclofen 2. However, phaclofen and structurally similar derivatives 3-5 did not cross the blood-brain barrier and hence were inactive in vivo as central nervous system agents. As a consequence, the therapeutic potential of GABAB antagonists remained unclear. In exploring GABA and baclofen derivatives by replacing the carboxylic acid residue with various phosphinic acid groups, we discovered more potent and water soluble GABAB antagonists. Electrophysiological experiments in vivo demonstrated that some of the new compounds were capable of penetrating the blood-brain barrier after oral administration. Neurotransmitter release experiments showed that they interacted with several presynaptic GABAB receptor subtypes, enhancing the release of GABA, glutamate, aspartate, and somatostatin. The new GABAB antagonists interacted also with postsynaptic GABAB receptors, as they blocked late inhibitory postsynaptic potentials. They facilitated the induction of long-term potentiation in vitro and in vivo, suggesting potential cognition enhancing effects. Fifteen compounds were investigated in various memory and learning paradigms in rodents. Although several compounds were found to be active, only 10 reversed the age-related deficits of old rats in a multiple-trial one-way active avoidance test after chronic treatment. The cognition facilitating effects of 10 were confirmed in learning experiments in Rhesus monkeys. The novel GABAB antagonists showed also protective effects in various animal models of absence epilepsy.

Level of functioning, severity of illness, and smoking status among chronic psychiatric patients

It was hypothesized that chronic psychiatric patients who had quit smoking would be more functional and have lower Brief Psychiatric Rating Scale (BPRS) scores than those who continued to smoke. We interviewed 300 chronic psychiatric patients followed in the community. Fourteen percent were former smokers and nearly 11% had never smoked. Fifty-six percent of the sample were current smokers who had no intention of quitting, 13% were considering quitting, and 6% were seriously preparing to quit or had actually quit for a short period. When compared with current smokers, former smokers were more likely to live independently (p < .026) and less likely to have a drug or alcohol problem (p < .013). A random sample of current smokers were compared with former smokers on the BPRS. Former smokers had lower total BPRS scores (p < .03), and lower withdrawal/retardation subscale scores (p < .0058) than current smokers. We concluded that better functioning patients who smoked would be more likely to quit.

CGP 35348: a centrally active blocker of GABAB receptors

The biochemical, electrophysiological and pharmacological properties of the new GABAB receptor blocker CGP 35348 are described. In a variety of receptor binding assays CGP 35348 showed affinity for the GABAB receptor only. CGP 35348 had an IC50 of 34 microM at the GABAB receptor. The compound antagonized (100, 300, 1000 microM) the potentiating effect of L-baclofen on noradrenaline-induced stimulation of adenylate cyclase in rat cortex slices. In electrophysiological studies CGP 35348 (10, 100 microM) antagonized the effect of L-baclofen in the isolated rat spinal cord. In the hippocampal slice preparation CGP 35348 (10, 30, 100 microM) blocked the membrane hyperpolarization induced by D/L-baclofen (10 microM) and the late inhibitory postsynaptic potential. CGP 35348 appeared to be 10-30 times more potent than the GABAB receptor blocker phaclofen. Ionophoretic and behavioural experiments showed that GABAB receptors in the brain were blocked after i.p. administration of CGP 35348. This compound may be of considerable value in elucidating the roles of brain GABAB receptors.

Age, pattern of consultation, and functional disability in elderly patients in one general practice

OBJECTIVE

To examine how functional disability varies with sex, age, and other variables in patients aged 75 and over living in the community and to ascertain whether a statistical model derived from the variables in this population usefully predicted functional disability in another of similar age.

DESIGN

Retrospective study of data collected by interview and by examination of medical records.

SETTING

An urban general practice with five partners and a list of 15,000 patients, very few of whom belonged to ethnic minorities.

PATIENTS

775 Patients (252 men, 523 women) aged 75 and over living in the community between September 1985 and August 1986; 13 other patients considered to be unsuitable and 14 who declined an interview were excluded. Also 94 patients who became 75 or joined the practice after August 1986.

MAIN OUTCOME MEASURE

The proportions of fit, partially disabled, and severely disabled (housebound) patients.

RESULTS

90 Men (35.7%) and 128 women (24.5%) were fit, and 27 men (10.7%) and 116 women (22.2%) were housebound; in all age groups women were significantly more likely to be disabled than men. A significant trend towards greater disability was shown with increasing age and, more noticeably, with pattern of consultation when patients were divided into three categories based on the number of times they had attended the surgery and been visited at home over about two years. Statistical models gave the forecast percentage of fit and severely disabled patients for each sex, age group, and pattern of consultation, and a simple scheme was derived to identify from information wholly contained in medical records most of those patients most prone to severe disability. The scheme was verified applying it to a population of 94 elderly patients in 1988-9.

CONCLUSION

Sex, age, and pattern of consultation together provide a quick indication of elderly patients' tendency to severe disability, which can help in screening and in day to day consultations.

3-Aminopropanephosphinic acid is a potent agonist at peripheral and central presynaptic GABAB receptors

The actions of the GABA analog 3-aminopropanephosphinic acid (3-APA) were studied in the guinea-pig isolated ileal preparation and at synapses between cultured rat hippocampal neurons. Like the GABAB receptor agonist, baclofen, 3-APA inhibited the electrically evoked ileal twitch. The EC50 for 3-APA was 0.8 microM; the EC50 for baclofen was 9 microM. In addition, the depressant responses to 3-APA and baclofen were blocked by the GABAB receptor antagonists phaclofen, saclofen, 2-hydroxy-saclofen and delta-aminovaleric acid. 3-APA also mimicked the presynaptic action of baclofen at GABAergic synapses between embryonic rat hippocampal neurons in culture. 3-APA reduced the amplitude of inhibitory postsynaptic potentials (IPSPs) and currents (IPSCs) by greater than 50% at a concentration of 1 microM, while baclofen reduced synaptic transmission to a similar degree at 10 microM. 3-APA did not alter membrane conductance, nor did the drug alter postsynaptic responses to GABA. These data show that 3-APA is a potent agonist at presynaptic GABAB receptors in the periphery and on GABAergic neurons from the central nervous system. The activity of 3-APA at central postsynaptic GABAB receptors remains to be studied.

Differing actions of baclofen and 3-amino-propylphosphinic acid in rat neocortical slices

Rat neocortical slices maintained in Mg2(+)-free Krebs medium developed spontaneous paroxysmal discharges which were attenuated or suppressed by the gamma-aminobutyric acid-B (GABAB) receptor agonist baclofen, occasionally accompanied by a slight hyperpolarisation, and antagonised by the specific GABAB-receptor antagonist, 2-OH-saclofen. Over the same dose range, the GABA-analogue 3-amino-propylphosphinic acid (3-APA) caused a marked, prompt hyperpolarisation with little or no effect on the frequency of the discharges, although their amplitude was attenuated. In the presence of 2-OH-saclofen, 3-APA still induced a hyperpolarisation but the amplitude of the discharges was no longer affected. This marked difference in action between baclofen and 3-APA in the rat neocortical slices suggests there may be a heterogeneity of GABAB-receptors.

GABAA and GABAB receptors in locus coeruleus: effects of blockers

Racemic baclofen, (-)-baclofen and muscimol depressed all spontaneously firing locus coeruleus neurons tested in a slice preparation. Racemic phaclofen (100 microM; 1 mM) moderately antagonized the effects of racemic baclofen without antagonizing those of muscimol. Bicuculline (10, 30, 100 microM) potently antagonized the action of muscimol without affecting the inhibition of baclofen. Phaclofen and bicuculline had no pronounced effect on the spontaneous discharge rate of cells. The results suggests that there are GABAA and GABAB receptors in the locus coeruleus.

A scale for the comparison of the sexual attitudes of adolescents and their parents

We developed a 14-item Attitudes Toward Sexuality Scale (ATSS) to compare the sexual attitudes of early, middle, and late adolescents and their parents. One hundred forty-one adolescents between the ages of 12 and 20 and their parents completed a questionnaire consisting of the ATSS and demographic information. The Cronbach alpha reliability coefficient for the adolescents was .75, and for the parents it was .84. A principal components analysis revealed four major dimensions of the scale: a large General factor, Legality/Morality, Alternative Modes of Sexual Expression, and Individual Rights. The correlation pattern between the ATSS and subscales of the Sex Knowledge and Attitudes Test, as well as with certain demographic variables, supports the construct validity of the ATSS. This is, therefore, a scale which may be used for research in which the sexual attitudes of adults and adolescents of various ages are to be measured and compared.

Drugs, insecticides and other agents from Artemisia

Essential oils from Artemisia (wormwood) are of botanical and pharmaceutical interest. They are used in traditional remedies in many parts of the world. In pure form the oil is a narcotic poison. Nearly all species are intensively bitter and strongly aromatic. Extracted substances from the plant have an antibacterial action and some of these substances have potential use in mosquito control. Other properties include toxicity to nematodes and inhibition of seedling growth of. Several chemical compounds have been isolated and identified.

Vein, Gore-tex or a composite graft for femoropopliteal bypass

Experience with a variety of graft materials has suggested that the nature of the material significantly affects long term graft patency. In 126 femoropopliteal bypass grafts performed during a 54 month period, the over-all patency rate for RSV (68.0 per cent at three years) was significantly superior to either Gore-tex alone (34.1 per cent at three years) or a composite graft of RSV below the knee anastomosed to Gore-tex above the knee (49.3 per cent at three years). The composite graft performed significantly better than Gore-tex alone, however, in patients with poor runoff or when a distal anastomosis was performed below the knee. The reason for the superior performance of RSV or the composite over Gore-tex alone probably relates to compliance mismatch at the site of the distal anastomosis. While RSV remains the graft material of choice for femoropopliteal bypass grafting, a extensive role exists for the use of a composite graft rather than Gore-tex graft alone especially in patients with poor runoff with an anastomosis below the knee.

Inflammatory aneurysms of the abdominal aorta

Over a 5 year period 268 abdominal aortic aneurysms were operated on, 15 of these (5.6%) showed the characteristic features of inflammatory aneurysms. Rupture of the aneurysm was an unusual method for presentation (one patient), and back and abdominal pain were present in 13 patients. The ESR may be of value in the pre-operative diagnosis. Ultrasound and CT scanning can, by the detection of a peri-aortic mass lead to confusion in the diagnosis. Two patients were initially diagnosed as having lymphoma. Strict adherence to the surgical principles outlined resulted in no mortality or significant morbidity in these 15 patients.

Effects of orally administered activated charcoal on intestinal gas

The effectiveness of activated charcoal in treating intestinal gas, following a gas producing meal, was compared with a placebo. Both the number of flatus events and breath hydrogen levels were measured. These experiments showed that orally administered activated charcoal was effective in preventing the large increase in the number of flatus events and increased breath hydrogen concentrations that normally occur following a gas-producing meal.

Effects of rapid smoking. Physiologic evaluation of a smoking-cessation therapy

We studied 24 healthy young male smokers to ascertain the medical safety of a highly effective smoking-abatement technique called rapid smoking. In comparison with results obtained after a 12-h cigarette fast or after normal smoking, statistically significant increases occurred after rapid smoking in heart and respiratory rates, systolic blood pressure, carboxyhemoglobin, and pH (p less than 0.05), while arterial PCO2, HCO3-, and serum [K+] fell (p less than 0.05). Rapid smoking produced alveolar hyperventilation in all subjects. In eight, arterial PO2 increased appropriately, but in 16, fell paradoxically (p less than 0.01); seven had arterial PO2 below 80 torr. Because this fall could represent ventilation/perfusion mismatch due to early bronchoconstrictive disease, in subjects with normal flow/volume loops and spirometry rapid smoking may be a simple, provocative screening test for early airway disease. Despite the changes produced there were no arrhythmias. Rapid smoking is safe for healthy subjects but should not now be used for higher-risk patients.

Endoscopy in the elderly

The endoscopic experience involving the study of 114 patients in the geriatric age group (65-89 years) in a district general hospital is described. The cases examined were mainly patients with dyspepsia, gastrointestinal blood loss, suspected upper alimentary tract carcinoma or those who had undergone gastric surgery. The procedure was well tolerated and safe. Useful information was obtained in the majority of patients (93 per cent). When the endoscopic and radiological findings were compared the endoscopist and radiologist were in agreement in 55 per cent of the cases examined by both techniques. In the others endoscopy played an essential role in establishing the presence of radiologically undetected or undetectable disease, and in confirming or excluding radiologically doubtful disease.