Transcatheter Aortic Valve Replacement and Impact of Subclinical Leaflet Thrombosis in Low-Risk Patients: LRT Trial 4-Year Outcomes

BACKGROUND

The LRT trial (Low-Risk Transcatheter Aortic Valve Replacement [TAVR]) demonstrated the safety and feasibility of TAVR in low-risk patients, with excellent 1- and 2-year outcomes. The objective of the current study is to provide the overall clinical outcomes and the impact of 30-day hypoattenuated leaflet thickening (HALT) on structural valve deterioration at 4 years.

METHODS

The prospective, multicenter LRT trial was the first Food and Drug Administration-approved investigational device exemption study to evaluate feasibility and safety of TAVR in low-risk patients with symptomatic severe tricuspid aortic stenosis. Clinical outcomes and valve hemodynamics were documented annually through 4 years.

RESULTS

A total of 200 patients were enrolled, and follow-up was available on 177 patients at 4 years. The rates of all-cause mortality and cardiovascular death were 11.9% and 3.3%, respectively. The stroke rate rose from 0.5% at 30 days to 7.5% at 4 years, and permanent pacemaker implantation rose from 6.5% at 30 days to 11.7% at 4 years. Endocarditis was detected in 2.5% of the cohort, with no new cases reported between 2 and 4 years. Transcatheter heart valve hemodynamics remained excellent post-procedure and were maintained (mean gradient 12.56±5.54 mm Hg and aortic valve area 1.69±0.52 cm²) at 4 years. At 30 days, HALT was observed in 14% of subjects who received a balloon-expandable transcatheter heart valve. There was no difference in valve hemodynamics between patients with and without HALT (mean gradient 14.94±5.01 mm Hg versus 12.3±5.57 mm Hg; P=0.23) at 4 years. The overall rate of structural valve deterioration was 5.8%, and there was no impact of HALT on valve hemodynamics, endocarditis, or stroke at 4 years.

CONCLUSIONS

TAVR in low-risk patients with symptomatic severe tricuspid aortic stenosis was found to be safe and durable at 4 years. Structural valve deterioration rates were low irrespective of the type of valve, and the presence of HALT at 30 days did not affect structural valve deterioration, transcatheter valve hemodynamics, and stroke rate at 4 years.

REGISTRATION

URL: https://www.

CLINICALTRIALS

gov; Unique identifier: NCT02628899.

Impact of Close Surveillance on Dual-Antiplatelet Therapy Compliance in Myocardial Infarction Patients Post-Percutaneous Coronary Intervention

BACKGROUND

Dual-antiplatelet therapy (DAPT) with aspirin and a P2Y12 receptor inhibitor is the mainstay regimen for acute coronary syndrome (ACS) patients after percutaneous coronary intervention (PCI). We aimed to investigate DAPT compliance and switching patterns in ACS patients prescribed ticagrelor and aspirin. Secondly, we evaluated the impact of a pilot strategy of close surveillance telephone calls.

METHODS

The study enrolled 150 consecutive ACS patients who underwent PCI and were prescribed DAPT (aspirin and ticagrelor). This cohort, the "close surveillance arm," then received telephone calls from a healthcare professional to inquire about DAPT for up to one year. These findings, and clinical outcomes, were then compared to a "historical arm" of ACS patients (n = 505) who received PCI and were prescribed DAPT before initiation of the program. Finally, healthcare providers were surveyed about their experience with prescribing DAPT.

RESULTS

The rate of ticagrelor cessation trended lower in the close surveillance arm (22.00 % versus 31.70 %, p = 0.0783). The most common reasons for ticagrelor cessation were adverse medication reaction (dyspnea), bleeding, and financial burden. Nevertheless, the adverse events were few and similar between the two groups during follow-up. Over 96 % of healthcare providers surveyed stated that they worry about their patients' DAPT compliance post-PCI.

CONCLUSION

Noncompliance and switching medications are still common for patients who undergo PCI for ACS. A close surveillance program identified patients at risk for medication cessation or switching and could potentially mitigate this phenomenon and improve quality of care.

The Clinical Profile and Natural History of Patients Who Fail Screening for Transcatheter Mitral Valve Replacement: Rationale and Design of the Prospective Multicenter Mitral Valve Screening Survey (MVSS)

Mitral valve disease is insidious and associated with a decreased quality of life and survival over time. Despite surgery being the standard of care, many patients are at prohibitive surgical risk. Furthermore, a substantial proportion of patients with symptomatic mitral valve disease fail stringent screening criteria for transcatheter mitral valve replacement (TMVR). The natural history of patients who fail screening is not well-characterized, and data are limited on the reasons for screen failure in this population. The Mitral Valve Screening Survey (MVSS) seeks to detail the clinical profile and natural history of patients who fail screening for TMVR. The MVSS is a prospective, multicenter registry enrolling up to 1000 consecutive subjects who, after screening for TMVR, are deemed not to be candidates. Subjects will be followed for 30 days after failing screening for TMVR and annually for up to 5 years with clinical evaluations. The primary study endpoint of the MVSS registry is all-cause mortality at 1 year. Additional secondary endpoints include all-cause mortality, hospitalizations, subsequent mitral valve intervention (transcatheter or surgical), reason for screen failure, and quality-of-life assessments at 30 days and annually up to 5 years of follow-up. The MVSS registry is the first prospective multicenter study to characterize the clinical and anatomical profile of patients who fail screening for TMVR while providing longitudinal clarification on the natural history and outcomes of these patients. CLINICAL TRIAL REGISTRATION: Mitral Valve Screening Survey (MVSS), https://clinicaltrials.gov/ct2/show/NCT04736667, NCT04736667.

Implementation of preemptive DNA sequence-based pharmacogenomics testing across a large academic medical center: The Mayo-Baylor RIGHT 10K Study

PURPOSE

The Mayo-Baylor RIGHT 10K Study enabled preemptive, sequence-based pharmacogenomics (PGx)-driven drug prescribing practices in routine clinical care within a large cohort. We also generated the tools and resources necessary for clinical PGx implementation and identified challenges that need to be overcome. Furthermore, we measured the frequency of both common genetic variation for which clinical guidelines already exist and rare variation that could be detected by DNA sequencing, rather than genotyping.

METHODS

Targeted oligonucleotide-capture sequencing of 77 pharmacogenes was performed using DNA from 10,077 consented Mayo Clinic Biobank volunteers. The resulting predicted drug response-related phenotypes for 13 genes, including CYP2D6 and HLA, affecting 21 drug-gene pairs, were deposited preemptively in the Mayo electronic health record.

RESULTS

For the 13 pharmacogenes of interest, the genomes of 79% of participants carried clinically actionable variants in 3 or more genes, and DNA sequencing identified an average of 3.3 additional conservatively predicted deleterious variants that would not have been evident using genotyping.

CONCLUSION

Implementation of preemptive rather than reactive and sequence-based rather than genotype-based PGx prescribing revealed nearly universal patient applicability and required integrated institution-wide resources to fully realize individualized drug therapy and to show more efficient use of health care resources.

Prosthetic valve endocarditis after transcatheter aortic valve replacement in low-risk patients

OBJECTIVES

We sought to report details of the incidence, organisms, clinical course, and outcomes of prosthetic valve endocarditis (PVE) after transcatheter aortic valve replacement (TAVR) in low-risk patients.

BACKGROUND

PVE remains a rare but devastating complication of aortic valve replacement. Data regarding PVE after TAVR in low-risk patients are lacking.

METHODS

We performed a detailed review of all patients in the low-risk TAVR trials who underwent TAVR from 2016 to 2020 and were adjudicated to have definitive PVE by the independent Clinical Events Committee.

RESULTS

We analyzed 396 low-risk patients who underwent TAVR (including 72 with bicuspid valves). PVE occurred in 11 patients at a median 379 days (210, 528) from TAVR. The incidence within the first 30 days was 0%; days 31-365, 1.5%; and after day 365, 2.8%. The most common organism identified was Streptococcus (n = 4/11). Early PVE (≤ 365 days) occurred in five patients, of whom three demonstrated evidence of embolic stroke and two underwent surgical aortic valve re-intervention. Late PVE (> 365 days) occurred in six patients, of whom thee demonstrated evidence of embolic stroke and only one underwent surgical aortic valve re-intervention. Of the six patients with evidence of embolic stroke, two died, two were discharged to rehabilitation, and two were discharged home with home care.

CONCLUSIONS

PVE was infrequent following TAVR in low-risk patients but was associated with substantial morbidity and mortality. Embolic stroke complicated the majority of PVE cases, contributing to worse outcomes in these patients. Efforts must be undertaken to minimize PVE in TAVR.

Integrating pharmacogenomics into the electronic health record by implementing genomic indicators

Pharmacogenomics (PGx) clinical decision support integrated into the electronic health record (EHR) has the potential to provide relevant knowledge to clinicians to enable individualized care. However, past experience implementing PGx clinical decision support into multiple EHR platforms has identified important clinical, procedural, and technical challenges. Commercial EHRs have been widely criticized for the lack of readiness to implement precision medicine. Herein, we share our experiences and lessons learned implementing new EHR functionality charting PGx phenotypes in a unique repository, genomic indicators, instead of using the problem or allergy list. The Gen-Ind has additional features including a brief description of the clinical impact, a hyperlink to the original laboratory report, and links to additional educational resources. The automatic generation of genomic indicators from interfaced PGx test results facilitates implementation and long-term maintenance of PGx data in the EHR and can be used as criteria for synchronous and asynchronous CDS.

A review of the evidence of zolpidem efficacy in neurological disability after brain damage due to stroke, trauma and hypoxia: A justification of further clinical trials

During 15 years, 23 clinical reports and 6 studies have demonstrated associations between sub-sedative doses of zolpidem and recoveries from brain damage due to strokes, trauma and hypoxia. Clinical findings include unexpected awakenings from vegetative states and regressions of stroke symptoms after dosing that disappear during elimination and reappear on repeat dosing. Initially single-photon emission computed tomography scans showed improved perfusion within, around and distant from infarctions. Then positron emission tomography scans and electroencephalography detected renewed metabolic and neuronal activity. Placebo or a similar, gamma-aminobutyric acid (GABA)-ergic, sedative zopiclone has no such effect. The effect appears only several months after the injury, reflecting recent evidence in mice of substantial differences between the states of GABA receptors in acute and chronic repair phases of recovery. Zolpidem's good safety record and rapid absorption further indicate a need for more clinical trials. List of acronyms: BOLD, Blood-Oxygen-Level Dependent contrast imaging in MRI; CRS, Coma Recovery Scale; CRS-R, Coma Recovery Scale Revised; CSI, Cerebral State Index; CSM, Cerebral State Monitor; DOC, Disorder of Consciousness; EEG, Electro Encephalography; FDG-PET, FluoroDeoxyGlucose-Positron Emission Tomography; FTD, Frontotemporal dementia; GABA, Gamma-Aminobutyric Acid; MCS, Minimally Conscious State; M-EEG, Magneto-Encephalography; MRI, Magnetic Resonance Image; MSN, Median Spiny Neurones; PET, Positron Emission Tomography; PVS, Persistent Vegetative Sate; RLAC, Rancho Los Amigos Cognitive scores; SPECT, Single-photon emission computed tomography; TFES, Tinetti Falls Efficacy Scale; 99mTc HMPAO, Technetium hexamethylpropyleneamine oxime.

Technical Challenges and Opportunities when Implementing Pharmacogenomics Decision Support Integrated in the Electronic Health Record

Clinical use of pharmacogenomic (PGx) knowledge at the bedside is new and complex. Our program has implemented multiple PGx-CDS interventions in different clinical settings and in multiple commercial EHRs. Herein, we discuss lessons learned and propose general technical guidelines related to PGx implementation.

Physiological interpretation of electrical impedance epigastrography measurements

Measurement of the electrical impedance of the gastric region is carried out with the epigastrograph. This generates and applies alternating current around the abdominal area and measures the potential difference in order to determine the impedance externally, via electrodes. The change of epigastric impedance for a subject, given a meal after fasting, depends on the conductivity of the meal compared to the stomach and surrounding tissues. Typically a conductive meal has conductivity >7 mS cm(-1), non-conductive <2 mS cm(-1) and neutral about 4.5 mS cm(-1). Half-emptying times (T50s) from gastric emptying studies in volunteers using three test meals of 450 ml volume were obtained and found to be shorter than expected from the literature. The meals were a 10% glucose solution and two milk shakes of energy 1,300 kJ and 2,850 kJ, respectively. These electrical impedance epigastrography (EIE) measurements were carried out with scintigraphy. The T50 values of the latter were significantly longer. The direct comparison of the normalized experimental data obtained by both methods led to the concept that EIE measurements are mainly influenced by gastric secretion. Thus the EIE trace of a 'neutral' meal suggests the hypothesis that the volume of the meal is not the significant factor but is influenced by gastric acid secretions. Physiology of the gastric mucosa during the digestion of a meal and intragastric pH values also suggests this. Gastric function studies using EIE measurements may therefore reflect gastric ionic concentration rather than the volume of the contents of the stomach. In turn this could lead to the development of a non-invasive method for the continuous recording of gastric acid secretions.

Solvent/detergent treatment does not alter the tolerance or uptake of human normal immunoglobulin for intramuscular injection

BACKGROUND AND OBJECTIVES

The tolerability and pharmacokinetics of a solvent/detergent-treated intramuscular immunoglobulin were compared with those of the standard product.

MATERIALS AND METHODS

Single, 750-mg intramuscular (i.m.) injections were administered to a total of 36 healthy individuals: 23 in a double-blind trial and 13 in an open trial. Changes in specific serum hepatitis A and hepatitis B antibodies were monitored for a period of up to 3 months postinjection.

RESULTS

No serious adverse reactions were reported, and the bioavailability of the solvent/detergent-treated preparation was equivalent to that of the standard i.m. immunoglobulin.

CONCLUSION

There is no evidence that solvent/detergent treatment alters the pharmacokinetics or tolerance of human normal immunoglobulin, but it offers additional assurance against potential virus transmission.

Sildenafil citrate potentiates the hypotensive effects of nitric oxide donor drugs in male patients with stable angina

OBJECTIVE

We sought to study the effects of a single oral dose of sildenafil citrate (50 mg) on blood pressure (BP) in men taking the nitric oxide (NO) donor drugs isosorbide mononitrate (ISMN) or glyceryl trinitrate (GTN) for stable angina.

BACKGROUND

Sildenafil, a selective phosphodiesterase type 5 inhibitor, is an orally effective treatment for erectile dysfunction. The presence of phosphodiesterases in the vasculature suggests the possibility of an interaction between sildenafil and NO donor drugs.

METHODS

Two double-blind, placebo-controlled, randomized, two-way crossover trials were undertaken. Sixteen male patients received oral ISMN (20 mg twice a day) for five to seven days before their dose of sildenafil or placebo and continued receiving ISMN daily until administration of the alternate drug seven days later. For the second study, 15 male patients received sublingual GTN (500 microg) 1 h after sildenafil or placebo on each of two study days, which were seven days apart. Sitting or standing BP was measured before and for 6 h after the administration of the study drug.

RESULTS

The effects of sildenafil plus ISMN on BP (standing mean maximum reductions from baseline in systolic/diastolic BP, -52/-29 mm Hg) were greater than the effects of placebo plus ISMN on BP (-25/-15 mm Hg; p < 0.001). Sildenafil plus GTN also resulted in greater sitting mean maximum reductions from baseline in systolic/diastolic BP (-36/-21 mm Hg) compared with placebo plus GTN (-26/-12 mm Hg; p < 0.01).

CONCLUSIONS

Coadministration of sildenafil with ISMN or GTN produced significantly greater reductions in BP than ISMN or GTN alone. Based on these data, sildenafil should not be administered to patients taking nitrates.

No effect of glucagon-like peptide-1 on short-term satiety and energy intake in man

Centrally administered glucagon-like peptide-1 (GLP-1) inhibits feeding in fasted rats, but its role in human satiety has been largely unexplored. The present study investigated the effect of peripheral GLP-1 infusion on gastric emptying and satiety in man. Ten non-obese male subjects were infused in a randomized single-blind within-subject crossover study using saline infusion as control. They received either a GLP-1 infusion (1.2 pmol/kg per min) or a saline infusion for 1 h, at 18.00 hours. At 20 min after starting the infusion the gastric emptying of a 400 ml water load was measured. Subjects completed behavioural self-rating scales to assess hunger and satiety. After 40 min subjects were given a buffet meal ad libitum and their food intake was recorded. GLP-1 infusion raised circulating GLP-1 concentrations to approximately twice those seen following a meal. It did not affect circulating insulin levels but caused a small fall in glucose levels. Gastric emptying of the water load was significantly delayed by the GLP-1 infusion. Energy intake from the buffet was unaffected by GLP-1 infusion. Self-assessment of hunger and satiety was similarly unaffected by the infusion before the buffet meal, although subjects tended to be less hungry after the buffet meal following GLP-1 infusion (P < 0.09). GLP-1 infusion delayed gastric emptying but had a minimal effect on food intake and satiety. This study casts doubts on whether GLP-1 is a major satiety factor in man, although a raised circulating plasma glucose level, as would normally occur postprandially, might be necessary for GLP-1 to increase satiety.

Opioid-induced delay in gastric emptying: a peripheral mechanism in humans

BACKGROUND

Opioids delay gastric emptying, which in turn may increase the risk of vomiting and pulmonary aspiration. Naloxone reverses this opiate action on gastric emptying, but it is not known whether this effect in humans is mediated by central or peripheral opiate antagonism. The importance of peripheral opioid receptor antagonism in modulating opioid-induced delay in gastric emptying was evaluated using methylnaltrexone, a quaternary derivative of the opiate antagonist naltrexone, which does not cross the blood-brain barrier.

METHODS

In a randomized, double-blind, crossover placebo-controlled study, 11 healthy volunteers were given either placebo (saline), 0.09 mg/kg morphine, or 0.09 mg/kg morphine plus 0.3 mg/kg methylnaltrexone on three separate occasions before ingesting 500 ml deionized water. The rate of gastric emptying was measured by two methods: a noninvasive epigastric bioimpedance technique and the acetaminophen absorption test.

RESULTS

The epigastric bioimpedance technique was sufficiently sensitive to detect opioid-induced changes in the rate of gastric emptying. The mean +/- SD time taken for the gastric volume to decrease to 50% (t0.5) after placebo was 5.5 +/- 2.1 min. Morphine prolonged gastric emptying to (t0.5) of 21 +/- 9.0 min (P < 0.03). Methylnaltrexone given concomitantly with morphine reversed the morphine-induced delay in gastric emptying to a t0.5 of 7.4 +/- 3.0 (P < 0.04). Maximum concentrations and area under the concentration curve from 0 to 90 min of serum acetaminophen concentrations after morphine were significantly different from placebo and morphine administered concomitantly with methylnaltrexone (P < 0.05). No difference in maximum concentration or area under the concentration curve from 0 to 90 min was noted between placebo and methylnaltrexone coadministered with morphine.

CONCLUSIONS

The attenuation of morphine-induced delay in gastric emptying by methylnaltrexone suggests that the opioid effect is mediated outside the central nervous system. Methylnaltrexone may have the potential to decrease the side effects of opioid medications, which are mediated peripherally, while maintaining the central analgesia effect of the opioid.

Comparative central nervous system effects and pharmacokinetics of neu-metoclopramide and metoclopramide in healthy volunteers

Metoclopramide, a drug used for the relief of nausea and emesis, is currently under development as a radio- and chemosensitizing agent. Its usefulness in high doses, however, is limited by its central nervous system side effects. Neu-metoclopramide (Neu-Sensamide), a novel, concentrated, phosphate-buffered, pH-adjusted (pH = 6.5-7.0) formulation of metoclopramide, has been shown to have an improved side-effect profile in animal studies. The present double-blind, four-way crossover study compared the central nervous system effects and pharmacokinetics of neu-metoclopramide (intravenously and intramuscularly at 1.8 mg/kg) with intravenous metoclopramide and intramuscular placebo in 19 healthy male volunteers. Eight participants withdrew from the study, one because of noncompliance and seven because of adverse events. A total of 28 central nervous system events were observed with intravenous metoclopramide administration, whereas 16, 15, and 6 such events were attributed to intravenous neu-metoclopramide, intramuscular neu-metoclopramide, and placebo, respectively. Extra-pyramidal effects occurred on 10 occasions: 7 after intravenous metoclopramide, 2 after intravenous neu-metoclopramide, and 1 after intramuscular neu-metoclopramide. No significant differences were observed in the pharmacokinetic profiles of the three formulations of metoclopramide. It may be speculated, therefore, that the molecular conformational changes inherent to neu-metoclopramide result in a reduced side-effect profile compared with conventional metoclopramide formulations.

The clinical pharmacology of single doses of otilonium bromide in healthy volunteers

OBJECTIVE

Otilonium is a smooth muscle spasmolytic with greater affinity for receptors in the smooth muscle of distal than proximal gut in rats. This study was the first to compare distal and proximal GI transit effects in human subjects.

METHODS

Using an increasing dose design for the safe exploration of clinical and supraclinical single dose levels, two groups of eight volunteers received either 40, 120 and 200 mg or 80, 160 and 240 mg otilonium. Gastric emptying of 400 ml 10% glucose solution was assessed by epigastric impedance (EI), orocaecal transit time (OCTT) by the lactulose breath-hydrogen method and whole gut transit time (WGTT) by the method of Hinton et al. [1]. Potential anticholinergic effects were assessed via visual accommodation using the RAF rule and saliva flow in response to sucking a sweet.

RESULTS

Median WGTT after 120 mg significantly increased by 4.1 h relative to placebo, but at higher doses median changes relative to placebo were not significant due to wide increases in group variance. The EI t50% was delayed by 1.4 min when results from the two highest doses were combined and compared with placebo; this small difference was statistically significant but seems unlikely to achieve physiological or clinical significance. OCTT, visual accommodation and saliva flow were unaltered. Otilonium bromide was well tolerated at all doses, due mainly to low systemic absorption.

Faeces feeding by adult Phormia regina (Diptera: Calliphoridae): impact on reproduction

Fresh beef liver, sugar, and five different types of faeces were evaluated as supportive diets for egg development in the blowfly Phormia regina. Females on a sugar diet were unable to develop follicles beyond stage 3, whereas liver proved to be the best diet for complete egg maturation. Some faecal diets were unable to support egg maturation when fed upon for a short period of time; however, longer periods of feeding produced complete egg maturation. The necessity to feed for longer periods of time in order to produce eggs on most of these diets was attributed to their low protein content. Males, in a shorter period of time than females, obtained enough protein from faeces to activate the neuroendocrine system involved in mating.

Requirement for HIV-1 TAR sequences for Tat activation in rodent cells

HIV-1 gene expression is activated via an interaction between the virally encoded Tat protein and a target RNA, TAR. TAR is located at the immediate 5' end of all viral mRNAs and comprises a partially base-paired stem with a tripyrimidine bulge in the upper stem and a hexanucleotide loop. In vitro, Tat binds specifically to the bulge and upper stem region with no requirement for the loop. In contrast, when Tat activation is analyzed in primate cells, mutations in the loop abolish activation, suggesting a critical role for loop binding cellular factors. However, in rodent cells the reverse is true. Messages with a mutation in the TAR loop are activated whereas messages harboring a wild-type TAR sequence are not activated. By testing the effect of mutations in the bulge and stem in the context of mutation in the loop we now show that this loop-independent activation by Tat in rodent cells requires the critical bulge-stem sequences needed for Tat binding in vitro. These data suggest that in rodent cells, as in vitro, Tat does not require a loop binding cofactor. In rodent cells containing human chromosome 12 (CHO12), however, Tat activation is both bulge and loop dependent. It appears that rodent cells, but not CHO12 cells, are refractory to the normal Tat/TAR activation pathway not by virtue of lacking a loop binding cofactor, but rather by the presence of a loop binding inhibitor of either Tat binding or the activation process.

A correlation between severity of migraine and delayed gastric emptying measured by an epigastric impedance method

1. This study examined the ability of a bioimpedance method to detect the delay in gastric emptying which occurs during attacks of migraine. 2. In 64 non-migraineur control patients and 46 migraine patients outside an attack, gastric emptying rates were within the predicted normal range. 3. In contrast, rates in 14 migraineurs during 20 attacks were delayed during severe or moderate attacks and were significantly correlated with the intensity of headache, nausea and photophobia. 4. The epigastric impedance method was generally well tolerated by patients and appears to merit further investigation as a clinical method of monitoring gastric emptying of liquids.

A comparison of the gastric and central nervous system effects of two substituted benzamides in normal volunteers

Eight healthy male volunteers participated in a single-blind, random allocation, crossover, comparison of intravenous metoclopramide (10 mg), the peripherally acting, gastrointestinal stimulant BRL 20627 (10 mg) and saline. The central nervous system effects were assessed by quantitative electroencephalography (EEG) and by visual analogue scales. Gastric motility and emptying were assessed by epigastric impedance. Metoclopramide increased the EEG amplitude by 10.4% (a statistically significant, P less than 0.05, effect) and increased frequencies above 22 Hz, whereas both BRL 20627 and placebo had only minor effect on the EEG frequencies and slightly decreased the EEG amplitude. Ratings on visual analogue scales showed that metoclopramide caused statistically significant (P less than 0.01 difference from placebo) restlessness and slight but significantly less (P less than 0.05 difference from placebo) feeling of happiness. Epigastic impedance changes indicated that both metoclopramide and BRL 20627 increased gastric contractile activity, but the rate of gastric emptying was not significantly altered by either drug although it tended to be shortened following metoclopramide but not BRL 20627 treatment. It is concluded that since the published animal data show that BRL 20627 has only weak dopamine antagonistic properties this study further implicates dopamine receptor blockade in the akathisia but not in the gastric effect of metoclopramide.

Epigastric impedance: a non-invasive method for the assessment of gastric emptying and motility

The impedance of the epigastrium to a 4 mA, 100 KHz AC current increases while liquids of low electrical conductivity are being drunk. Logically, the decline which follows occurs as the liquid leaves the stomach. This impedance measurement of gastric emptying proved comparable with the dye dilution method. In a placebo controlled trial the impedance method recorded significantly faster gastric emptying rates after metoclopramide. The impedance trace contains regular activity in the 2-4 cycle/min range consistent with gastric contractions. This non-invasive and technically simple method may thus provide a measure of simultaneous gastric emptying rates and motility.

Measurement of gastric emptying rates by radioactive isotope scanning and epigastric impedance

When liquids of low electrical conductivity enter the stomach the impedance of the epigastric region to a 4 mA, 100 kHz current increases. There follows a decline, which logically represents gastric emptying. This method of measuring gastric emptying was compared against scintigraphy in six volunteers, and similar results were obtained. Impedance monitoring is entirely noninvasive, inexpensive, simple, and quick. The method merits further exploration.

Bioavailability and pharmacokinetics of clavulanic acid in healthy subjects

The bioavailability and pharmacokinetics of clavulanic acid were studied following oral solution and rapid intravenous administration to healthy volunteers. Plasma and urine samples were collected at frequent intervals following dose administration and were assayed for clavulanic acid by an enzyme inhibition method. Plasma data after intravenous administration were subjected to pharmacokinetic analysis using a two-compartment open model. The mean absolute bioavailability of clavulanic acid from oral solution was 0.75, derived from both urine and plasma data. No changes in the disposition pharmacokinetics of clavulanic acid with route were found, with a mean renal clearance of 0.1051 X min-1 and mean terminal elimination rate constant of 0.0134 min-1.

Pilot investigation of the quantitative EEG and clinical effects of ketazolam and the novel antiemetic nonabine in normal subjects

Nonabine is a chromenol structurally related to the cannabinoids which has shown antiemetic efficacy in clinical trials. Oral doses of 5, 10, and 15 mg were given to healthy volunteers in a crossover study with the benzodiazepine ketazolam, 30 and 45 mg. Ketazolam produced sedative effects, with decreased quantitative EEG alpha activity and increased beta activity. Nonabine also produced sedative clinical effects, but with an EEG profile which resembled that reportedly caused by cannabinoids. In contrast to cannabinoids, nonabine did not cause changes of mood or perception, suggesting that nonabine lacks the potential for social abuse at antiemetic doses.

Adverse reactions to intravenous anaesthetics

One hundred consecutive reports of reactions to intravenous anaesthetics Althesin, thiopentone and Epontol are reviewed and analysed. Ten reactions are attributed to causes other than the anaesthetic drug, and four are believed to have been caused by the muscle relaxant employed. The remaining 86 reactions were grouped according to their clinical presentation: histaminoid reactions ( 19), histaminoid with bronchospasm (33), bronchospasm (12), cardiovascular collapse (uu), delayed histaminoid reactions (6), and clonic contractions (5). None of the first four reaction types was associated with only one anaesthetic. A knowledge of the sales of Althesin has allowed the incidence of reactions to be estimated as between one in 11,000 and one in 19,000.

Sensitivity to intravenous anaesthetics: a report of three cases

Three patients with sensitivity to an intravenous anaesthetic-thiopentone, propanidid, and Althesin (alphadolone and alphaxalone)-are described. In the cases of thiopentone and Althesin the reaction was characterized by cardiovascular collapse, while bronchospasm also occurred with thiopentone. The reaction to propanidid was a direct skin sensitivity. All patients had a personal or family history of asthma and all had been previously exposed to the offending drug. A leucocyte challenge test showed an allergic response to thiopentone and Althesin in two patients but gave a negative result in the patient with the skin reaction. Allergic reactions can occur to all types of intravenous anaesthetics in a few patients.