SQ-standardized house dust mite immunotherapy as an immunomodulatory treatment in patients with asthma

BACKGROUND

  Specific immunotherapy is the only treatment with the potential to prevent progression of the allergic disease and the potential to cure patients. The immunomodulatory ability of SQ-standardized house dust mite (HDM) subcutaneous immunotherapy (SCIT) was investigated in patients with allergic asthma.

METHODS

Fifty-four adults with HDM-allergic asthma were randomized 1:1 to receive SQ-standardized HDM SCIT (ALK) or placebo for 3 years. At baseline, and after 1, 2 and 3 years of treatment, the lowest possible inhaled corticosteroid dose required to maintain asthma control was determined, followed by determinations of nonspecific and HDM-allergen-specific bronchial hyperresponsiveness, late asthmatic reaction (LAR), immediate and late-phase skin reactions, and immunological response.

RESULTS

  SQ-standardized HDM SCIT provided a statistically significantly higher HDM-allergen tolerance (P<0.05 vs placebo) in terms of a 1.6-fold increase in PD(20) (HDM-allergen inhalation challenge), a 60-fold increase in skin test histamine equivalent HDM-allergen concentrations, reduced immediate- and reduced or abolished late-phase skin reactions, as well as fewer patients with LAR. PD(20) (methacholine inhalation challenge) increased initially and was similar between groups. House dust mite SCIT induced an initial increase in serum HDM-allergen-specific IgE (P=0.028 vs placebo), which then declined to baseline value. House dust mite SCIT induced an increase in components blocking IgE binding to allergen [ΔIgE-blocking factor: 0.31; 95% CI of (0.26; 0.37)] after 1 year that remained constant after 2 and 3 years (P < 0.0001 vs placebo).

CONCLUSION

  SQ-standardized HDM SCIT induced a consistent immunomodulatory effect in adults with HDM-allergic asthma; the humoral immune response was changed and the HDM-allergen tolerance in lung and skin increased.

Steroid-sparing effect of subcutaneous SQ-standardised specific immunotherapy in moderate and severe house dust mite allergic asthmatics

BACKGROUND

The present study evaluated the steroid-sparing effect of subcutaneous SQ-standardized specific immunotherapy (SIT) in moderate and severe house dust mite (HDM) allergic asthmatics.

METHODS

Fifty-four adult asthmatics allergic to HDM requiring at least inhaled corticosteroids (ICS) doses equivalent to 500 microg fluticasone propionate daily were randomized to subcutaneous SIT or placebo injections for a period of 3 years. The minimum required ICS dose, 4 week diary of asthma symptom score, use of rescue medication, peak expiratory flow (PEF) measurements and visual analog scale for asthma symptoms were assessed before start of treatment and after 1, 2 and 3 years of treatment.

RESULTS

In patients with moderate and severe asthma, the reduction in ICS was statistical significant after 2 years of treatment (P = 0.03) but not after 3 years. The median reductions were 82% and 42% after the third year for active and placebo respectively. In patients with moderate persistent asthma the reduction was statistical significant larger for those treated with SIT compared with placebo after year 2 and year 3. The median reductions after 3 years were 90% for SIT and 42% for placebo (P = 0.04). Despite significant steroid reduction, there was no difference in asthma assessments between the two groups. No serious reactions related to SIT injections were seen.

CONCLUSION

This study shows that SIT with a SQ-standardized HDM extract is safe. An ICS sparing effect was evident in patients with moderate persistent asthma.

Steroid-sparing effect of subcutaneous SQ-standardised specific immunotherapy in moderate and severe house dust mite allergic asthmatics

BACKGROUND

The present study evaluated the steroid-sparing effect of subcutaneous SQ-standardized specific immunotherapy (SIT) in moderate and severe house dust mite (HDM) allergic asthmatics.

METHODS

Fifty-four adult asthmatics allergic to HDM requiring at least inhaled corticosteroids (ICS) doses equivalent to 500 microg fluticasone propionate daily were randomized to subcutaneous SIT or placebo injections for a period of 3 years. The minimum required ICS dose, 4 week diary of asthma symptom score, use of rescue medication, peak expiratory flow (PEF) measurements and visual analog scale for asthma symptoms were assessed before start of treatment and after 1, 2 and 3 years of treatment.

RESULTS

In patients with moderate and severe asthma, the reduction in ICS was statistical significant after 2 years of treatment (P = 0.03) but not after 3 years. The median reductions were 82% and 42% after the third year for active and placebo respectively. In patients with moderate persistent asthma the reduction was statistical significant larger for those treated with SIT compared with placebo after year 2 and year 3. The median reductions after 3 years were 90% for SIT and 42% for placebo (P = 0.04). Despite significant steroid reduction, there was no difference in asthma assessments between the two groups. No serious reactions related to SIT injections were seen.

CONCLUSION

This study shows that SIT with a SQ-standardized HDM extract is safe. An ICS sparing effect was evident in patients with moderate persistent asthma.

Population pharmacokinetics of tiagabine in epileptic patients on monotherapy

A retrospective study of the population pharmacokinetics of tiagabine was performed from sparse data collected in a multicentre clinical trial in patients with newly diagnosed partial seizures. The purpose was to estimate the inter patient variability and to study the influence of various demographic, environmental and pathophysiological parameters on the pharmacokinetics of tiagabine in patients on monotherapy. A total of 593 plasma concentrations from 130 patients dosed with 2.5, 5, 7.5 or 10 mg tiagabine twice daily were used for modelling. A one-compartment open model with first-order absorption and elimination was fitted to the concentration-time data using the NONMEM program. Selection of covariates was initially performed using stepwise linear regression analyses. The selected covariates were incorporated in the population model and the importance of each covariate was investigated by means of backwards elimination. A one-compartment model with first-order absorption and elimination adequately described the tiagabine concentration-time profile. The apparent clearance as well as the apparent volume of distribution were both significantly correlated to body height in a nonlinear relationship. No other demographic, environmental or clinical chemical parameters were identified as covariates although only a few pathological values of the latter were present in the data. The mean values of CL/f was 6.10 l/h, of V/f was 62.0 l and of k(a) was 1.25 h(-1) for a subject of 170-cm height. The population half-life was 5.72 h. The apparent clearance and volume of distribution of tiagabine in epilepsy patients on monotherapy were both dependent on body height. Prospective studies are required in order to reveal if dose adjustments based on body height will result in improved therapeutic outcome.

Lack of pharmacokinetic interaction between tiagabine and erythromycin

This study was conducted to investigate the effects on the pharmacokinetics of tiagabine at steady state when coadministered with therapeutic doses of erythromycin. Tiagabine doses of 4 mg twice daily and erythromycin doses of 500 mg twice daily were administered for 4 days in an open-label, crossover, two-period interaction trial in 13 healthy volunteers. No statistically significant differences in maximum plasma concentration (Cmax), area under the concentration-time curve (AUC tau), or half-life (t1/2) of tiagabine were observed when tiagabine was administered alone or in combination with erythromycin. A statistically significant treatment effect was observed for time to maximum concentration (tmax; 0.72 after tiagabine alone versus 0.56 hours after administration with erythromycin). No statistically significant differences were seen between men and women except in tmax and t1/2; these differences were thought to be of no clinical significance. The decrease in tmax seen in women in this study is interpreted as a differential effect of erythromycin on gastric emptying of females and not as an interaction between tiagabine and erythromycin. No changes in laboratory parameters or vital signs were attributable to trial medication. The most common treatment-emergent adverse events that were possibly related to trial medication were central nervous system effects (e.g., headache, dizziness); all adverse events were transient, the majority were rated mild in severity, and did not require additional action. Coadministration of erythromycin in healthy subjects does not significantly affect the pharmacokinetics of tiagabine at the doses tested.