Depressants

Depressants Depress the central nervous system by interfering with the transmission of neural impulses in the nerve cells (neurons) Depress the central nervous system by interfering with the transmission of neural impulses in the nerve cells (neurons)

Effects of Depressants Slow down bodily functions especially motor activity and mental activity Slow down bodily functions especially motor activity and mental activity Low doses Low doses –Feelings of calm and reduced anxiety –Induced sleep Large doses Large doses –Loss of consciousness, coma, death

Alcohol Ethanol is the only common alcohol that can be consumed. Other common alcohols such as methanol and isopropyl are much too toxic Ethanol is the only common alcohol that can be consumed. Other common alcohols such as methanol and isopropyl are much too toxic Alcohols are used as antiseptics for injections and to harden skin Alcohols are used as antiseptics for injections and to harden skin

Alcoholism Prolonged consumption of alcohol leads to both psychological and physiological dependence Prolonged consumption of alcohol leads to both psychological and physiological dependence Alcoholism also results in Alcoholism also results in –Violent antisocial behavior –Social costs to families –Safety issues especially road accidents

Alcohol Consumption Short term effects Short term effects –Relaxation, confidence, and increased sociability –Dialation of blood vessels leads to feelings of warmth –Impaired judgment –Lengthened neural response time

Alcohol consumption Long term effects of heavy drinking Long term effects of heavy drinking Cirrhosis of the liver and liver disease Cirrhosis of the liver and liver disease Coronary heart disease Coronary heart disease High blood pressure and strokes High blood pressure and strokes Dementia Dementia Miscarriage Miscarriage Fetal abnormalities and fetal alcohol syndrome Fetal abnormalities and fetal alcohol syndrome

Alcohol Withdrawal Sudden discontinuation of alcohol by heavy drinkers leads to withdrawal symptoms including Sudden discontinuation of alcohol by heavy drinkers leads to withdrawal symptoms including –Delirium –Tremors’

Synergistic effects of ethanol increased risk of stomach bleeding with aspirin increased risk of stomach bleeding with aspirin increased risk of heavy sedation with any drug that has a sedative effect on the central nervous system. increased risk of heavy sedation with any drug that has a sedative effect on the central nervous system.

Legal limits for driving Most states in the US and many countries have established 0.08% blood alcohol as the legal limit for driving Most states in the US and many countries have established 0.08% blood alcohol as the legal limit for driving After drinking the concentration of alcohol in the blood (BAC) increases as the alcohol is absorbed and then gradually declines After drinking the concentration of alcohol in the blood (BAC) increases as the alcohol is absorbed and then gradually declines

Alcohol detection Breathalyser tests Breathalyser tests Reduction of potassium dichromate to Cr 3+ ion Reduction of potassium dichromate to Cr 3+ ion Fuel cell where alcohol is oxidized to produce an electric current Fuel cell where alcohol is oxidized to produce an electric current Gas Chromatography Gas Chromatography Infrared spectroscopy- intoximeter Infrared spectroscopy- intoximeter

Breathalyzer test involves a redox reaction in which acidified K 2 Cr 2 O 7 is used as the oxidizing agent. It oxidizes any alcohol in the breath to ethanoic acid. The orange Cr(VI) is reduced to green Cr(III) with the gain of three electrons per Cr. The two half reactions and the overall reaction are:

The redox reaction, involving transfer of electrons generates, an e.m.f. that is converted to a signal in the breathalyzer device to indicate the BAC in the sample of breath. Such devices generally suffer from inaccuracy and unreliability when used in legal cases. More accurate analysis is carried out by gas liquid chromatography (glc) and infra-red spectroscopy.

Intoximeter Police use the Intoximeter to confirm a road side breathalyzer test. This is an IR spectrophotometer in which the IR radiation is passed through the breath sample. If alcohol is present, the frequencies are absorbed by the sample depending on the bands present (such as C–H and O–H) and the rest of the radiation is transmitted. The recorder then produces the IR spectrum as % transmittance against wavenumber. Intoximeter does not distinguish between ethanol and propanone which is often present in the breadth of a diabetic patient.

Gas Liquid Chromatography unlike the Intoximeter, gas chromatography is able to distinguish between ethanol and propanone (found in the breadth of diabetics).

Other Depressants Certain medicines known as antidepressants are used to treat anxiety, stress, and clinical depression Certain medicines known as antidepressants are used to treat anxiety, stress, and clinical depression These include These include –Diazepam (Valium) –Nitrazepam –Fluoxetine hydrochloride (Prozac)

Fluoxetine Hydrochloride(Prozac) Prozac is an example of the selective serotonin reuptake inhibitor (SSRI) Prozac is an example of the selective serotonin reuptake inhibitor (SSRI) SSRIs work by preventing neurons (nerve cells) from pulling in the serotonin that is floating in the space between neurons. This allows more serotonin to build up and improves communication between the neurons. SSRIs work by preventing neurons (nerve cells) from pulling in the serotonin that is floating in the space between neurons. This allows more serotonin to build up and improves communication between the neurons.

Prozac ® (Fluoxetine hydrochloride) is an anti-depressant drug that is used to treat mental depression and is thought to work by increasing the activity of serotonin, a neurotransmitter, in the brain. The chemical structure of Prozac® is unlike that of Valium® or Mogadon®. Prozac® contains the amine group which can react with HCl to produce fluoxetine hydrochloride which is water soluble.

Tranquilizers Valium Valium is a sedative drug. It is the most prescribed drug in the world and is used in the relief of anxiety and tension. It is believed to function by inhibiting nerve transmission by interacting with neurotransmitters.

Nitrazepam Nitrazepam (Mogadon®, a common sleeping pill) is a hypnotic drug that induces sleep and it is also used to control seizures and infantile spasms.

Valium® and Mogadon ® are synthetic drugs known as benzodiazepines. Both have a common structure consisting of a phenyl (C 6 H 5 ) group, a fused benzene ring with a seven membered heterocyclic ring consisting of two nitrogen atoms, one of which is a secondary amine. On the fused benzene ring, valium contains Cl whereas Mogadon® contains the NO2 group.

Barbiturates are short acting, and include pentobarbital, secobarbital, and amobarbital. Affect the cortex and create a state similar to alcoholic intoxication in large doses. Extremely dangerous when mixed with alcohol or other drugs. A person in withdrawal suffers anxiety, agitation, loss of appetite, nausea and vomiting, sweating, a fast heartbeat, tremors, and cramps. These symptoms can escalate to convulsions, delirium, and hallucinations.Barbituates

How depressants affect behaviour