Insights into the molecular mechanism of triazolopyrimidinone derivatives effects on the modulation of α1β2γ2 subtype of GABAA receptor: An in silico approach

Due to the importance of benzodiazepine drugs in clinical practice, such as the treatment of anxiety disorders, depression, and insomnia and the side effects of classical benzodiazepines, the study of new benzodiazepine agonists has received much attentions. In this work, we used in silico methods to explore the molecular mechanism of 1,2,4-triazolo [1,5--a] pyrimidinone derivatives in the modulation of α₁β₂γ₂ subtype of GABA_A receptor. To this aim, molecular docking, molecular dynamics simulation (MD), post-MD analysis, binding free energy calculation, and prediction of ADME properties were performed. Results showed that all new compounds have a better binding affinity for the Benzodiazepine (BZD) site of the receptor than diazepam and compound 4c had the highest affinity among them. Moreover, a good agreement was observed between the calculated ΔG_binding and experimental IC₅₀ values. Also, we noticed that residues in loop regions (particularly loop C and D-F in α₁ and γ₂ subunits, respectively) forming BZD binding site, take part in forming several H-bonds between the agonists and the receptor. Ser205, Thr207, Tyr160, and His102 of α₁ subunit and Thr207 of γ₂ subunit are mainly involved in forming H-bonds. Also, the orientation of agonists in the BZD binding site leads to π-π interactions with hydrophobic residues in loops A-F. Based on the DCCM analysis, the correlated motions in the γ₂ subunit residues are greater than those of α₁ subunit residues. Further, predicted ADME results indicated that all agonists meet the criteria. The triplicate MD simulation showed the reproducibility of the results and strengthened the study. Our results provide a comprehensive insight into the receptor-agonist interactions and clues for designing future BZD agonists.

Long-term persistence of withdrawal of temazepam, zopiclone, and zolpidem in older adults: a 3-year follow-up study

BACKGROUND

Studies on persistence of benzodiazepine agonist (BZDA) withdrawal in older outpatients are few, and few studies on long-term persistence over years have yet been published. To describe the persistence of temazepam, zolpidem, and zopiclone (BZDA) withdrawal among older outpatients at 3 years from the beginning of withdrawal, as well as any changes in use of other medications.

METHODS

92 outpatients (≥55 years) with primary insomnia, long-term BZDA use as hypnotics (mean duration of BZDA use 9.9 ± 6.2 years), and willingness to withdraw from BZDAs each received either melatonin or a placebo nightly for one month. During this period, BZDAs were meant to be gradually withdrawn. Sleep hygiene counselling and psychosocial support were provided. Three years later, use of BZDAs and other medications was determined by interview and confirmed from medical records.

RESULTS

Of the original 92 outpatients, 83 (90%) participated in the 3-year survey (mean follow-up 3.3 ± 0.2 years). The number of BZDA-free participants decreased from 34 (37%) at 6 months to 26 (28%; intention-to-treat) at 3 years, that of irregular BZDA users decreased from 44 (48%) at 6 months to 27 (29%) at 3 years, while that of regular users increased from 11 (12%) at 6 months to 30 (33%) at 3 years (P = 0.001). Those who were regular BZDA users at 3 years had at baseline (before withdrawal) higher BMI (P = 0.001) than did other participants. At 3 years, the total number of medications remained unchanged for non-users (P = 0.432), but increased for the irregular (P = 0.011) and regular users (P = 0.026) compared to baseline. At 3 years, compared to baseline, use of antidepressants, dopamine agonists, melatonin, and NSAIDs/paracetamol was significantly more common in the whole cohort, but their use did not differ between the BZDA-user subgroups. Randomization to melatonin or placebo during BZDA withdrawal was unrelated to BZDA-withdrawal result.

CONCLUSIONS

At 3 years after withdrawal, the number of BZDA-free participants had decreased, but still one-third of the subjects remained BZDA-free, and one-third had reduced their use. Successful BZDA withdrawal did not lead to any increase in total number of medications; use of symptomatic medications in the whole cohort, however, did increase.