Journal Athaar Yosuef Jaha User 4263 Sedative /Hypnotics/Anxiolytics drug (Barbiturates) Introduction According to what I studied about (Barbiturates). I will write a journal about it. Barbiturate is one of the most famous drug , using for several reasons as, sedative, anxiolytics to relief the feeling of Distress or uneasiness of mind caused by fear of danger or misfortune, and as hypnotics for people who suffering from insomnia . these disorders are belong to psychological situations or to defect in body functions. I will also remind it is mechanism of action, types , (SAR) Structure –activity relationship. To get simple,interesting, and benefit information about this drug. Body Barbiturates are drugs that act on central nervous system as depressant and it's one of the older drug choice. And can cause relaxation and sleeping in relatively low doses . Barbiturate bind to specific sites on gamma-aminobutyric acid (GABA) heteromultimeric structure contain α,β,δ,ε,γ,π polypeptide subtypes. And they work on (β) .it's sensitive ion channels found in the central nervous system (CNS),where they allow an influx of chloride into cell membranes and subsequently hyper polarize the post synaptic neuron . Their types :1-long duration barbiturate barbital (5,5diethylbarbituric acid), phenobarbital (5-ethyl-5-phenyl barbituric acid). e.g (Phenobarbital) 2-Intermediate duration of action Amobarbital(5-ethyl 5-isopentile barbituric acid), butabarbital(5-secbutyl 5 ethylbarbituric acid). e.g (Amobarbital) 3- Short duration barbiturates pentobarbital(5-ethyl 5-secpentyl barbituric acid), secobarbital (5-allyl5-secpentyl • barbituric acid) e.g Pentobarbital (SAR) Structure activity relationship :In order to possess good hypnotic activity, a barbiturate must be a weak acid and must have a lipid /water partition coefficient between certain limit. In position number (5) , R1 and R2 may be : alkayl group ,arayl group, or Benzen ring. In position number (1) ,(H)N may it be R3 as H,CH3 and the last is more lipophilicity. In position number (3), NH give the acidity . After reading about Barbiturate, I knew different types of it ,their mechanism of action ,and the structure activity relationship,I had a correlation between the information that I study it in pharmacology and now in medicinal chemistry, and I though it's big benefit for me to remember the information and make it stuck in my mind. Conclusion At the end of my writing about barbiturates, I realized that the comparing between different types of barbiturates it's depend on their Potency ,not on their efficacy .because they all give the same effects but in different durations and potency. And they work as depressant agent on central nervous system on GABA receptor , for several reasons as, sedative ,anxiolytics ,and hypnotics . and you must know that ,It's an important kind of the drugs that people may can't live with out it . just by taking the cautions and follow the instruction.