♠HOW DRUGS ACTING ON THE CENTRAL NERVOUS SYSTEM. Alcohol is a hydrocarbon. They may contain one or more hydroxyl OH groups. Ethyl alcohol is the commonly used alcohol.
♠What is ethyl alcohol Ethyl alcohol is the main constituent of all kinds of alcoholic beverages. It is generally obtained by fermentation of sugar by yeast.
♠ How many types of PHARMACOLOGICAL ACTION. Nine types of PHARMACOLOGICAL ACTION OF drugs.
1) External:- External alcohol is:-
A) astringent:- since it precipitates protein.
B) refrigerant:- since it produces a cooling effect on the skin.
C) rubefacient:- since it dilates cutaneous blood vessels.
D) detergent:- it dissolves sebaceous secretion.
E) antiseptic:- since it destroys micro-organisms.
2) Gastrointestinal tract:- Alcohol increases gastric acid secretion and also produces a carminative effect.
3)Liver:- Produce fatty liver on chronic administration.
4)Central nervous system:- Alcohol produces initial excitation (characterized by incoherent speech and gait) due to depression of higher inhibitory centers. This is followed by progressive depression, drowsiness, sleep, and unconsciousness as the dose is increased.
5) Cardiovascular system:- Moderate dose of alcohol produces cutaneous vasodilation. This creates a feeling of flushing and warmth. A concentration of alcohol slightly raises blood pressure and increases heart rate due to reflecting action.
6) Respiration:- Moderate doses produce slight stimulation, whereas large amounts produce respiratory depression, which may be fatal.
7) Kidney:- Output of urine is increased due to depression of ADH production.
8)Sexual function:- Alcohol produces an aphrodisiac action ( excretion of sexual organ) due to loss of inhibitory control. Also, it provokes the sensation but takes away the performance.
9)Food value:- Alcohol gives rise to energy due to its rapid utilization. But it is not a proper food because the energy production is not sufficient even for basal metabolism.
♠ How absorption, fate, and excretion is done:-
Alcohol is absorbed in the stomach (25%) and small intestine (75%). It is metabolized in the liver as follows:- Ethyl Alcohol------Acetaldehyde Acetaldehyde---- Acetyl COA Acetyl CoA is further metabolized to carbon dioxide and water. Alcohol is eliminated chiefly through the kidneys and lungs.
♠WHAT IS ACUTE ALCOHOLISM:-
The symptoms of acute alcoholism are incoherence, incoordination, fall in body temperature and blood pressure, and respiratory depression. Treatment consists of stomach wash, oxygen inhalation, maintenance, of warmth and injection of analeptics.
♠ What is chronic alcoholism.
The manifestation of chronic alcoholism is atrophic changes in the Gastrointestinal tract, degenerative changes in the liver and nerves. Also, addiction and withdrawal symptoms may develop.
♠ WHAT IS DISULFIRAM ( TETRAETHYL THIRUM DISULFIDE ANTABUSE):-
It is a drug used for the treatment of chronic alcoholism. It acts by inhibitors the enzymes aldehyde dehydrogenase. So acetaldehyde is not converted into Acetyl CoA. This leads to the accumulation of acetaldehyde which produces nausea and vomiting. It is administered at a dose of 500mg. Once-daily for a week and later 250mg. Daily as a maintenance dose. Adverse effects:- Drowsiness, headache, cramps, and a metallic taste in the mouth.
♠WHAT IS METHYL ALCOHOL (METHANOL):- It is known as wood alcohol since it is prepared by destructive distillation of wood. It is unsuitable for drinking since it produces a poisoning effect. Formaldehyde, a metabolic product of methyl alcohol, damages optic nerves leading to blindness. In case of poisoning with methyl alcohol, ethyl alcohol is given. Ethyl alcohol is metabolized preferentially over methyl Alcohol. So methyl alcohol is excreted unchanged. In addition to this, sodium bicarbonate ( to counteract acidosis)and folinic acid may also be administered.
♠WHAT IS FOMEPIZOLE:- It is an antidote for methyl Alcohol. It inhibits the enzymes Alcohol dehydrogenase. So formaldehyde and formic acid, the toxic metabolites, are not formed.
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