A Phase 2 Trial of Sibeprenlimab in Patients with IgA Nephropathy

BACKGROUND

A proliferation-inducing ligand (APRIL) is implicated in the pathogenesis of IgA nephropathy. Sibeprenlimab is a humanized IgG2 monoclonal antibody that binds to and neutralizes APRIL.

METHODS

In this phase 2, multicenter, double-blind, randomized, placebo-controlled, parallel-group trial, we randomly assigned adults with biopsy-confirmed IgA nephropathy who were at high risk for disease progression, despite having received standard-care treatment, in a 1:1:1:1 ratio to receive intravenous sibeprenlimab at a dose of 2, 4, or 8 mg per kilogram of body weight or placebo once monthly for 12 months. The primary end point was the change from baseline in the log-transformed 24-hour urinary protein-to-creatinine ratio at month 12. Secondary end points included the change from baseline in the estimated glomerular filtration rate (eGFR) at month 12. Safety was also assessed.

RESULTS

Among 155 patients who underwent randomization, 38 received sibeprenlimab at a dose of 2 mg per kilogram, 41 received sibeprenlimab at a dose of 4 mg per kilogram, 38 received sibeprenlimab at a dose of 8 mg per kilogram, and 38 received placebo. At 12 months, the geometric mean ratio reduction (±SE) from baseline in the 24-hour urinary protein-to-creatinine ratio was 47.2±8.2%, 58.8±6.1%, 62.0±5.7%, and 20.0±12.6% in the sibeprenlimab 2-mg, 4-mg, and 8-mg groups and the placebo group, respectively. At 12 months, the least-squares mean (±SE) change from baseline in eGFR was -2.7±1.8, 0.2±1.7, -1.5±1.8, and -7.4±1.8 ml per minute per 1.73 m2 in the sibeprenlimab 2-mg, 4-mg, and 8-mg groups and the placebo group, respectively. The incidence of adverse events that occurred after the start of administration of sibeprenlimab or placebo was 78.6% in the pooled sibeprenlimab groups and 71.1% in the placebo group.

CONCLUSIONS

In patients with IgA nephropathy, 12 months of treatment with sibeprenlimab resulted in a significantly greater decrease in proteinuria than placebo. (Funded by Visterra; ENVISION ClinicalTrials.gov number, NCT04287985; EudraCT number, 2019-002531-29.).

Safety, Pharmacokinetics, and Pharmacodynamics of Subcutaneous Sibeprenlimab in Healthy Participants

Sibeprenlimab blocks the cytokine "A Proliferation-Inducing Ligand" (APRIL), which may play a key role in immunoglobulin A nephropathy pathogenesis. A phase 1 study of subcutaneous (SC) sibeprenlimab evaluated preliminary safety, tolerability, pharmacokinetics, and pharmacodynamics in healthy participants. This was an open-label, single-ascending-dose study. Twelve participants in each of 4 sequential dosing cohorts received 1 SC dose of sibeprenlimab (200 mg [1×1 mL injection], 400 mg [2×1 mL injections], 400 mg [1×2 mL injection], or 600 mg [1 mL+2 mL injections]) and underwent 16-week follow-up for adverse events, pharmacokinetics, and pharmacodynamics (serum APRIL, immunoglobulin [Ig] levels). Sibeprenlimab in single SC doses of 200-600 mg was slowly absorbed into the systemic circulation, with a median time to maximum serum concentration of approximately 6-10.5 days, and a mean elimination half-life of approximately 8-10 days. Serum APRIL, IgA, IgM, and, to a lesser extent, IgG decreased in a dose-dependent and reversible manner. Maximal reduction in serum IgA was approximately 60% at the 400- and 600-mg doses and 40% at 200 mg. Serum APRIL rapidly decreased to near the lower limit of quantification, and duration of suppression was dose-dependent, with near complete suppression until weeks 4-6 at the 400-mg dose and week 8 at the 600-mg dose. Adverse events occurred in 30/48 (62.5%) participants; none were serious or led to study discontinuation. Sibeprenlimab rapidly and sustainably reduced target APRIL and Ig biomarkers in a dose-dependent and reversible manner, with acceptable preliminary safety and pharmacokinetics.

Safety, tolerability, pharmacokinetics and pharmacodynamics of VIS649 (sibeprenlimab), an APRIL-neutralizing IgG2 monoclonal antibody, in healthy volunteers

Introduction

VIS649 (sibeprenlimab), a humanized IgG₂ monoclonal antibody that inhibits APRIL, is being developed as a potential treatment for IgA nephropathy (IgAN). This phase 1, first-in-human, randomized, double-blind, single ascending dose study aimed to evaluate the safety, pharmacokinetics (PK), and pharmacodynamics (PD) of VIS649 in healthy adults.

Methods

Participants were randomized to VIS649 (sequential i.v. dosing cohorts: 0.5, 2.0, 6.0, 12.0 mg/kg) or placebo; a further cohort received VIS649 6.0 mg/kg or placebo followed by a tetanus/diphtheria vaccine challenge.

Results

A total of 51 participants were randomized, dosed, and analyzed for safety (7 for each VIS649 dose; 8 for placebo; 10 for VIS649 + vaccine; 5 for placebo + vaccine). There were no serious adverse events (AEs) or AEs leading to study discontinuation. VIS649 had nonlinear PK: half-life increased with dose and drug exposure increased in a greater than dose-proportional manner. Serum APRIL, IgA, galactose-deficient (Gd) IgA₁, IgG, and IgM were reversibly suppressed in a dose-dependent manner, with a dose–response in time to recovery. Tetanus and diphtheria serum IgG titers increased after recall vaccination.

Conclusion

VIS649 was safe, well tolerated, and reversibly suppressed APRIL and various immunoglobulins, without loss of antigen-specific vaccination response. Further clinical development of VIS649 for IgAN is warranted. Trial registration: ClinicalTrials.gov: NCT03719443.

MO283IMPACT OF VIS649, AN APRIL-NEUTRALIZING IGG2 MONOCLONAL ANTIBODY, ON TETANUS- AND DIPHTHERIA-TOXOID VACCINATION-ELICITED IMMUNE RESPONSES IN HEALTHY VOLUNTEERS: PHASE 1, RANDOMIZED, DOUBLE-BLIND, PLACEBO-CONTROLLED STUDY

Background and Aims

VIS649, a humanized immunoglobulin G (IgG2) monoclonal antibody that binds to and blocks the biological actions of a proliferation-inducing ligand (APRIL), is in clinical development as a potential treatment for immunoglobulin A (IgA) nephropathy (IgAN). In a Phase 1 study, VIS649 was associated with dose-dependent reductions in serum IgA, IgG and IgM, which were reversible and showed a dose-response effect with respect to time-to-recovery. The aim of the present analysis was to determine if VIS649 suppression of APRIL influences antibody responses to tetanus and diphtheria toxoid vaccination.

Method

This was a Phase 1, randomized, double-blind, placebo-controlled, single ascending dose study of VIS649 in healthy adult male and female volunteers (ClinicalTrials.gov identifier: NCT03719443). In one cohort within the study, participants were randomized in a 2:1 ratio to receive intravenous administration of VIS649 6.0 mg/kg or placebo, followed by a vaccine composed of tetanus and diphtheria toxoids (TENIVAC®, Sanofi Pasteur Limited), in order to evaluate the effect of VIS649 on recipients’ ability to generate a vaccine booster response (exploratory endpoint). Participants received intravenous administration of study drug on Day 1, were discharged from the institution on Day 2, received a single intramuscular dose of vaccine at the Week 4 visit, and were followed for 16 weeks in total on an outpatient basis. Blood samples were taken at regular intervals, and anti-tetanus toxoid and anti-diphtheria toxoid IgG, IgM and IgA quantitative ELISA assays were performed. Tetanus and diphtheria anti-toxoid IgG titers ≥0.1 IU/mL are generally considered to be protective.

Results

In the vaccination cohort, 15 participants were randomized and dosed with study drug or placebo, of whom 14 completed the study, and one participant who received VIS649 was lost to follow-up prior to receiving the vaccine. Both groups (placebo and VIS649) demonstrated increased tetanus anti-toxoid IgG titers following immunization, with a mean 7.9-fold increase in IU/mL at Week 6 for placebo recipients and a mean 6.4-fold increase in IU/mL for VIS649 recipients (Figure). At visits after Week 6, tetanus anti-toxoid IgG titers declined faster in the VIS649 group than in the placebo group (consistent with the reduction in total IgG associated with VIS649 administration) but remained above the protective threshold of 0.1 IU/mL for all participants throughout the study. Similar trends were observed for diphtheria anti-toxoid IgG titers, with a mean 5.5-fold increase in IU/mL at the Week 6 visit for placebo recipients and a mean 5.1-fold increase for VIS649 recipients (Figure). There was no evidence of tetanus- or diphtheria-toxoid elicited IgM responses in either the placebo or VIS649 groups, consistent with the recall nature of the vaccination. In a post hoc analysis, pre-existing serum tetanus/diphtheria anti-toxoid IgA titers fell between Day 1 and Week 4 in the VIS649 group, consistent with the overall suppression of total serum IgA, were boosted after vaccination in both groups, and declined faster in the VIS649 recipients thereafter.

Conclusion

VIS649 treatment did not interfere with participants’ ability to mount an antigen-specific serum IgG or IgA boost response to tetanus and diphtheria toxoid vaccination. There was no evidence of tetanus- or diphtheria-specific IgM responses in either the placebo or VIS649 groups, consistent with recall vaccination exposure. These data indicate that qualitative antibody responses are preserved during APRIL suppression.

MO258SAFETY, TOLERABILITY, PHARMACOKINETICS AND PHARMACODYNAMICS OF VIS649, AN APRIL-NEUTRALIZING IGG2 MONOCLONAL ANTIBODY, IN HEALTHY VOLUNTEERS: PHASE 1, RANDOMIZED, DOUBLE-BLIND, PLACEBO-CONTROLLED, SINGLE ASCENDING DOSE STUDY

Background and Aims

Immunoglobulin A (IgA) nephropathy (IgAN) is a glomerulonephritis characterized by the presence of circulating and glomerular immune complexes containing galactose-deficient (Gd) IgA1. A proliferation-inducing ligand (APRIL), a member of the tumor necrosis factor superfamily of ligands, is thought to play a key role in the pathogenesis of IgAN by virtue of its role in class-switching to IgA production. VIS649, a humanized immunoglobulin G (IgG2) monoclonal antibody that binds to and blocks the biological actions of APRIL, is in clinical development as a potential treatment for IgAN. The primary objective of this first-in-human study was to evaluate the safety and tolerability of VIS649 in healthy volunteers. Secondary objectives included characterization of the pharmacokinetics (PK) and pharmacodynamics (PD) of VIS649.

Method

This was a Phase 1, randomized, double-blind, placebo-controlled, single ascending dose study of VIS649 in healthy adult male and female volunteers (ClinicalTrials.gov identifier: NCT03719443). The study was conducted in sequential dosing cohorts. The first four cohorts (0.5, 2.0, 6.0, and 12.0 mg/kg, respectively) each enrolled 9 participants (4 of Japanese descent and 5 of non-Japanese descent) who were randomized to VIS649 or placebo in a ratio of 7:2. In addition, a fifth cohort enrolled 15 adults randomized to receive VIS649 6.0 mg/kg or placebo (10:5), followed by tetanus/diphtheria vaccine challenge after 28 days (TENIVAC®, Sanofi Pasteur Limited; the effect of APRIL inhibition on vaccine response is described in a companion abstract). Participants received intravenous administration of study drug on Day 1, were discharged from the institution on Day 2, and were followed for 16–24 weeks on an outpatient basis. Standard safety assessments and blood sampling for PK and PD were performed at regular intervals.

Results

51 participants were randomized and dosed with study drug, of whom 47 (92.2%) completed the study. VIS649 was well tolerated, with no serious adverse events (AEs) or AEs that led to study discontinuation. Most treatment-emergent AEs (TEAEs) were mild; the incidence and severity of TEAEs were not dose dependent. One participant in the 2.0 mg/kg group experienced a severe TEAE of syncope following phlebotomy that the investigator considered unlikely to be related to study drug. There was no clinically relevant effect of treatment on laboratory tests, vital signs, electrocardiogram parameters, or physical examinations. VIS649 had non-linear PK: half-life (t½) increased with dose, while drug exposure (AUC) increased in a greater than dose proportional manner. Serum IgA, Gd-IgA1, IgG, and IgM were reversibly suppressed in a dose-dependent manner following VIS649 administration. The maximum mean percentage reductions from baseline occurred at Week 12 for the 12.0 mg/kg dose: IgA, -57.2% (Figure); Gd-IgA1, -71.6% (Figure); IgG, -33.6%; and IgM, -67.2%. These reductions were reversible and showed a dose-response effect with respect to time-to-recovery. Mean free (non-VIS649 bound) serum APRIL levels decreased to the lower limit of quantification (50 pg/mL) for all VIS649 doses at Week 1, and also showed a dose-response effect with respect to time-to-recovery. No depletions in circulating lymphocyte populations were observed. There were no significant PK or PD differences between Japanese and non-Japanese participants.

Conclusion

A single dose of VIS649, up to 12.0 mg/kg, was safe and well tolerated in healthy adults and was able to suppress free serum APRIL to the lower level of quantification. Serum Gd-IgA1 decreased in parallel with total serum IgA and recovered in a dose-dependent manner following reappearance of free APRIL in serum. These data support the further clinical development of VIS649 as a potential treatment for IgAN.

Disposition of firocoxib in equine plasma after an oral loading dose and a multiple dose regimen

The objective of this study was to determine if a single loading dose (LD), 3× the label dose of firocoxib oral paste, followed by nine maintenance doses at the current label dose achieves and maintains near steady state concentrations. Six healthy, adult mares were administered 0.3mg/kg of firocoxib on Day 0, and 0.1 mg/kg 24 h later on Day 1, and at 24 h intervals from Day 2 to Day 9, for a total of 10 doses. Blood samples were collected throughout the study. The mean firocoxib maximum plasma concentration and standard deviation was 199±97 ng/mL, 175±44 ng/mL and 183±50 ng/mL after the LD, and first and last maintenance doses, respectively. The minimum mean concentration (C(min)) increased from 100±23 ng/mL after the LD to 132±38 ng/mL at Day 7. Then, the C(min) remained constant until Day 9. The average concentration at steady state (C(avg)) was 150±45 ng/mL, which compares well to the C(avg) (130±36 ng/mL) reported after multiple daily doses at 0.1 mg/kg. The administration of the single LD allowed achievement of the average steady state drug concentrations faster than a multi-dose regimen without a loading dose. After the LD, firocoxib at 0.1 mg/kg every 24 h was able to maintain a relatively constant average drug concentration which should produce less variability in onset of action and efficacy.

The 1996 Paso del Norte Ozone Study: analysis of meteorological and air quality data that influence local ozone concentrations

The 1996 Paso del Norte Ozone Study and subsequent data analyses were implemented to develop an understanding of the chemical and physical processes which lead to high concentrations of ozone in the Paso del Norte study area which includes El Paso County, Texas, Sunland Park, New Mexico, and Ciudad Juárez, Mexico. Both the data and data analysis results are being used to support photochemical grid modeling. El Paso County and Sunland Park fail to meet the National Ambient Air Quality Standard (NAAQS) for ozone, and neighboring Ciudad Juárez fails to meet the Mexican ambient standard for ozone. This paper summarizes the measurement campaigns of the 1996 Paso del Norte Ozone Study and the findings and conclusions that arose from subsequent data analyses. Data analyses showed that high ozone concentrations resulted from a combination of conditions, including high surface temperatures, strong sunlight with few clouds, light surface winds and high concentrations of ozone precursors at ground level in the morning, and slow convective boundary layer (CBL) growth. Synoptic-scale meteorological conditions observed during high ozone episodes included an aloft high-pressure system and aloft warming. Aloft carryover of ozone and ozone precursors did not significantly contribute to high concentrations of ozone at the surface.

Compilation and evaluation of a Paso del Norte emission inventory

Emission inventories of ozone precursors are routinely used as input to comprehensive photochemical air quality models. Photochemical model performance and the development of effective control strategies rely on the accuracy and representativeness of an underlying emission inventory. This paper describes the tasks undertaken to compile and evaluate an ozone precursor emission inventory for the El Paso/Ciudad Juárez/Southern Doña Ana region. Point, area and mobile source emission data were obtained from local government agencies and were spatially and temporally allocated to a gridded domain using region-specific demographic and land-cover information. The inventory was then processed using the US Environmental Protection Agency (EPA) recommended Emissions Preprocessor System 2.0 (UAM-EPS 2.0) which generates emissions files compatible with the Urban Airshed Model (UAM). A top down evaluation of the emission inventory was performed to examine how well the inventory represented ambient pollutant compositions. The top-down evaluation methodology employed in this study compares emission inventory ratios of non-methane hydrocarbon (NMHC)/nitrogen oxide (NOx) and carbon monoxide (CO)/NOx ratios to corresponding ambient ratios. Detailed NMHC species comparisons were made in order to investigate the relative composition of individual hydrocarbon species in the emission inventory and in the ambient data. The emission inventory compiled during this effort has since been used to model ozone in the Paso del Norte airshed (Emery et al., CAMx modeling of ozone and carbon monoxide in the Paso del Norte airshed. In: Proc of Ninety-Third Annual Meeting of Air & Waste Management Association, 18-22 June 2000, Air & Waste Management Association, Pittsburgh, PA, 2000).

Suicide by cop

STUDY OBJECTIVE

"Suicide by cop" is a term used by law enforcement officers to describe an incident in which a suicidal individual intentionally engages in life-threatening and criminal behavior with a lethal weapon or what appears to be a lethal weapon toward law enforcement officers or civilians to specifically provoke officers to shoot the suicidal individual in self-defense or to protect civilians. The objective of this study was to investigate the phenomenon that some individuals attempt or commit suicide by intentionally provoking law enforcement officers to shoot them.

METHODS

We reviewed all files of officer-involved shootings investigated by the Los Angeles County Sheriff's Department from 1987 to 1997. Cases met the following criteria: (1) evidence of the individual's suicidal intent, (2) evidence they specifically wanted officers to shoot them, (3) evidence they possessed a lethal weapon or what appeared to be a lethal weapon, and (4) evidence they intentionally escalated the encounter and provoked officers to shoot them.

RESULTS

Suicide by cop accounted for 11% (n=46) of all officer-involved shootings and 13% of all officer-involved justifiable homicides. Ages of suicidal individuals ranged from 18 to 54 years; 98% were male. Forty-eight percent of weapons possessed by suicidal individuals were firearms, 17% replica firearms. The median time from arrival of officers at the scene to the time of the shooting was 15 minutes with 70% of shootings occurring within 30 minutes of arrival of officers. Thirty-nine percent of cases involved domestic violence. Fifty-four percent of suicidal individuals sustained fatal gunshot wounds. All deaths were classified by the coroner as homicides, as opposed to suicides.

CONCLUSION

Suicide by cop is an actual form of suicide. The most appropriate term for this phenomenon is law enforcement-forced-assisted suicide. Law enforcement agencies may be able to develop strategies for early recognition and handling of law enforcement-forced-assisted suicide (suicide by cop). Health care providers involved in the evaluation of potentially suicidal individuals and in the resuscitation of officer-involved shootings should be aware of law enforcement-forced-assisted suicide as a form of suicide.

A novel delta opioid agonist, BW373U86, in squirrel monkeys responding under a schedule of shock titration

The squirrel monkey titration procedure was used to assess the antinociceptive effects of the novel delta opioid agonist (+/-)-4-(a-R*)-a(2S*,5R*)-4-allyl-2,5-dimethyl-1-piperazinyl)-3-hydroxyb enzyl)- N,N-diethylbenzamide (BW373U86). Under this procedure shock increased every 15 sec from 0.01 to 2.0 mA in 30 steps. Five responses terminated the shock for 15 sec, after which the shock resumed at a lower intensity. The intensity at which the monkeys maintained the shock 50% of the time (median shock level, MSL) was determined. BW373U86 (1.0-30.0 mg/kg i.m.) increased MSL, but these increases were not dose-dependent and lasted only 15 min or less. Doses of BW373U86 that increased MSL often produced tremors and/or convulsions immediately after administration. When 1.0 mg/kg of naltrindole, a delta opioid antagonist, was given in combination with BW373U86, doses of BW373U86 up to 30 mg/kg no longer increased MSL nor did tremors and/or convulsions occur. Doses of BW373U86 (0.01-0.3 mg/kg i.m.) that did not increase MSL when administered alone shifted the dose-effect curve for the mu agonist l-methadone to the left. These shifts were antagonized dose-dependently by naltrindole. In monkeys that were tolerant to morphine, BW373U86 (0.03-0.1 mg/kg i.m.) shifted the morphine dose-effect curve leftward. In addition, BW373U86 altered the effects of the partial opioid agonists, buprenorphine, nalbuphine, butorphanol and levallorphan such that doses of these drugs that did not increase MSL when administered alone, often did so in the presence of BW373U86. Taken together, these findings indicate that BW373U86 has a delta agonist profile in the squirrel monkey; however, its antinociceptive effects in the shock titration procedure may be due to its toxic effects.

Agonist and antagonist effects of mixed action opioids in the pigeon drug discrimination procedure: influence of training dose, intrinsic efficacy and interanimal differences

The stimulus effects of selective, high efficacy mu opioids and mixed action opioids with varying degrees of intrinsic efficacy at the mu receptor were examined in pigeons trained to discriminate between saline and either 0.056 (low) or 0.18 (high) mg/kg of fentanyl. The stimulus profiles produced by the various opioids could be separated into three groups: 1) opioids that substituted completely for both training doses of fentanyl, with steep slopes and little interanimal differences in the lowest dose (lowest discriminable dose) that produced complete substitution (fentanyl, morphine and l-alpha-acetylmethadol); 2) opioids that substituted completely for the low training dose and produced high levels of substitution for the high training dose, with relatively shallow slopes and interanimal differences in the lowest discriminable dose (butorphanol, buprenorphine, ethylketocyclazocine, ketocyclazocine, proxorphan, (-)-pentazocine and (-)-metazocine); and 3) opioids that substituted completely for the low training dose, with relatively shallow slopes and large interanimal differences in the lowest discriminable dose. Each of these opioids also antagonized the high-dose fentanyl stimulus with large interanimal differences in the lowest antagonist dose (nalbuphine, nalorphine, (-)-cyclorphan, (-)-cyclazocine, (-)-n-ally-normetazocine and levallorphan). These patterns of substitution and antagonism most likely reflect differences in the intrinsic efficacy of these drugs at the mu receptor, with low intrinsic efficacy associated with shallow dose-effect functions, large interanimal differences in the drug's lowest discriminable dose and low levels of substitution for the high-dose fentanyl stimulus. During antagonism tests with naloxone, two patterns were observed: 1) opioids against which naloxone had apparent pA2 values of approximately 7.0, with little interanimal differences and with the slopes of the Schild plots approximating -1.0 (fentanyl and morphine) and 2) opioids against which naloxone had apparent pA2 values an order of magnitude higher, with large interanimal differences and with the slopes of Schild plots being relatively shallow (butorphanol, nalbuphine, nalorphine and levallorphan). The present findings emphasize the importance of training dose, intrinsic efficacy and interanimal differences when analyzing drug discrimination data.

Carbohydrate and oxygen metabolism during hepatocellular proliferation: a study in perfused livers from mirex-treated rats

Liver regeneration after partial hepatectomy is accompanied by altered hepatic intermediary metabolism. Because the organochlorine compound mirex also causes liver cell growth, the purpose of this study was to investigate hepatic carbohydrate and oxygen metabolism in perfused livers from mirex-treated rats and to localize cell proliferation in this model. Pretreatment with mirex (100 mg/kg, intragastrically) increased liver/body weight ratios and DNA synthesis in livers of fed rats, effects that were markedly diminished in livers of fasted rats. This finding shows that liver growth caused by mirex, as is the case after partial hepatectomy, is hindered when animals are deprived of food. Furthermore, perfused livers from mirex-treated rats had depleted glycogen stores but significantly elevated oxygen uptake compared with livers from control rats. Increases in oxygen uptake and hepatocellular proliferation were observed mostly in periportal regions of the liver lobule. In regenerating livers, most DNA synthesis was reported to also occur in these regions of the liver lobule. Taken together, these data show that liver cell growth caused by mirex is accompanied by changes in hepatic intermediary metabolism and sublobular proliferation similar to those observed after partial hepatectomy.

Cross-tolerance and enhanced sensitivity to the response rate-decreasing effects of opioids with varying degrees of efficacy at the mu receptor

The purpose of the present experiment was to determine whether the effects of opioids with varying degrees of efficacy at the mu receptor are differentially altered in morphine-tolerant pigeons. To this end, dose-effect curves were determined for high, intermediate, and low efficacy mu agonists in pigeons responding under a schedule of food presentation prior to, during, and after exposure to a regimen of chronic morphine administration. In pigeons treated with 56 mg/kg/daily morphine, the dose-effect curves for the rate-decreasing effects of the high-efficacy mu agonists morphine and fentanyl were shifted to the right of their prechronic positions (i.e., tolerance). A small degree of tolerance was also conferred to the intermediate-efficacy mu agonists (-)-pentazocine and (-)-metazocine, but not to nalbuphine or butorphanol. In contrast to the effects obtained with these mu agonists, the chronic morphine regimen shifted the dose-effects curves of the mu antagonist naloxone and the low-efficacy mu agonists nalorphine and levallorphan to the left of their prechronic positions (i.e., enhanced sensitivity). These findings demonstrate that morphine tolerance confers cross-tolerance to other high efficacy mu agonists, enhanced sensitivity to mu antagonists and low efficacy mu agonists, and little or no cross-tolerance to intermediate efficacy mu agonists. Disadvantages of using schedule-controlled responding to examine the effects of intermediate efficacy mu agonists are discussed.

Metered dose inhaler induced bronchospasm in asthmatic patients

Beta-adrenergic agonists in metered dose inhalers (MDIs) are used extensively in the treatment of asthma. Previously we reported that 23 of 1450 (1.6%) of our asthmatic patients experienced immediate bronchoconstriction after using MDI-albuterol. In this study we investigated immediate bronchoconstriction after use of MDI-metaproterenol and after placebo-inhaler with "inert ingredients" only. Results suggest that those patients who complained of chest tightness or lack of relief following the use of MDI beta-adrenergic agonists are having true bronchoconstriction. The bronchoconstrictive response is most likely caused by the propellants or the other inert ingredients contained in these MDIs.

Cromolyn modifies histamine bronchial reactivity in symptomatic seasonal asthma

Sixteen adults with symptomatic seasonal asthma were treated with either cromolyn or placebo during the pollen season, in a double blinded fashion. Over the study time (three months) bronchial histamine tolerance increased in the treated group while decreasing in the placebo group (P less than .002 at three months). Other measurements, such as FEV1, PEFR and symptom scores supported the idea that cromolyn therapy benefitted the course of seasonal asthma.

Effects of ascorbic acid on pulmonary functions in mild asthma

Twenty subjects with mild asthma took a short course of moderately high doses of Vitamin C (500 mg four times daily for 3 days and 1 g prior to spirometric evaluation). There were no differences in pulmonary functions just prior to and after therapy. There were no adverse reactions noted. If, as reported, Vitamin C has a beneficial effect in asthma, it does not appear to be due to a bronchodilatory effect.