Drugs
Introduction
- DRUG According to “WHO“ can be defined as “A Drug is any substance that is used to modify or explore physiological structures or pathological states for the benefit of the recipient.”
- Eg: paracetamol, ciprofloxacin, sal-butamol, or it can be said that
- The definition of drug in pharmacology, can be stated as “a chemical substance used in the treatment, cure, prevention or diagnosis of disease or otherwise used to enhance physical or mental well-being.” For chronic disorders, Drugs can be prescribed for a limited duration or on a regular basis.
- Drugs which are taken from outside the organism this usually distinguished from endogenous biochemical. For example, when hormone insulin is synthesized in the body; it is called a hormone when it is synthesized by the pancreas inside the body, but it is called a drug when it is introduced into the body from outside.
Classification of Drugs
On the basis of the purpose of their use, different drugs can be classified into following two
heads: ·
- Therapeutic Drugs
- Psychoactive Drugs
Therapeutic Drugs : A Therapeutic drug is a substance that has healing or preventive properties in relation to certain diseases, or is administered to enable a medical diagnosis.
The therapeutic drugs are classified chiefly into following four
categories:
- Analgesics and Antipyretics : An analgesic is a type of drug that relives pain. On the other part, an antipyretic is a type of drug that is used to reduce the temperature of the body. Aspirin and Paracetamol are the commonly used drugs in this category Aspirin and Paracetamol are the commonly used drugs in this category.
- Aspirin (Acetylsalicylic Acid) is a white crystalline powder having an acidic taste and is used commonly in houses for pains, aches, etc. Even small doses of this drug may prove to be fatal due to idiosyncrasy. However, minimum fatal dose is about 5-10 grams.
- Paracetamol (Acetaminophen) is a metabolite of phenacetin, and is widely in use these days in place aspirin. Ingestion of 20 tablets of 500 milligram each within three to five days is proved to be fatal.
2. Antihistaminics : These are the drugs which antagonize the action of histamine. These are
commonly used in allergic disorders and other conditions like common cold. The common
preparations include: Promethazine hydrochloride (Phenergan), Diphenhydramine (Benadryl),
Chlorcyclizine (Histantin), Antazoline (Antistine), etc. Its fatal dose is about one gram.
3. Antidepressants :These are the drugs which are generally used in psychiatric disorders to
treat the endogenous depression. These drugs have an initial sedative effect which is followed by an antidepressant effect within a week or more. Commonly used antidepressant drugs are:
Imipramine, Amitriptyline, etc.
4. Tranquilizers : These are the drugs that produce a general tranquility without the impairment
of high- thinking facilities or the inducement of a sleep. To reduce tension and anxiety of
mental patients Tranquilizers like reserpine and chlorpromazine are useful
Hence these are the four groups in which we classify therapeutic drugs . Now lets move to Psychoactive drugs
Psychoactive Drugs
Psychotropic drug is a chemical substance that acts principally upon the central nervous
system where it affects brain function, resulting in modification in perception, mood,
consciousness, cognition and behaviour
Psychoactive drugs bring about marked changes in consciousness and mood that the user
may find pleasant Despite health risks and neglecting consequences, many psychoactive
substances are misused/ abused, that is, used excessively, with continuous use of some
substances, psychological and physical dependence ("addiction") may develop.
Generally used psychoactive drugs are:- Narcotics, stimulants, Hallucinogens, Depressants and
Anabolic steroids.
1) Narcotics :The term is originated from Greek word narkotikos that means ‘a state of
lethargy’. This group comprises of substances that act on the CNS and bring relief from
discomfort and produce sleep. The origin of most narcotics is opium, a sticky milky juice
obtained from the unripe pod of poppy (Papaver somniferium). Example: Opium, morphine,
heroin, codeine, synthetic opiates, etc.
2) Stimulants : Stimulants consist of substances that, stimulates the mind, wakes
one up and euphoria (a feeling of well-being), but do not affect perception. These drugs are
also referred in the terminology of “speed”. Examples: Amphetamines,
methamphetamines, caffeine, nicotine, cocaine, etc.
3) Hallucinogens : including psychedelics, dissociatives and deliriants. This category comprises
all those substances that produce distinct alterations in normal thought processes,
perceptions and mood. There are a number of substances with varying chemical
compositions that have hallucinogenic properties. Examples: LSD (lysergic acid
diethylamide), PCP (phencyclidine), DMT (dimethyltryptamine), mescaline, psilocybin, etc
4) Depressants : including sedatives, hypnotics, and narcotics. This category consist
of all of the sleep inducing, calmative, anxiety-reducing, anesthetizing substances, which
induces perceptual changes like dream sequences, . Examples: Alcoholic beverages
(ethanol), barbiturates, benzodiazepines, etc.
LSD is synthesized from lysergic acid, a substance derived from ergot, which is a type of fungus
that attacks certain type of grains. This is a very potent drug, only 25 mg is sufficient to start
clear visual hallucinations in the mind that may last for about 12 hours. This drug produces
noticeable changes in mood, leading to laughing and crying at the slightest provocation. Feeling
of anxiety and tension always accompanied LSD use.
Marijuana is an example of a psychoactive drug that combines properties of each of these
groups. Cannabis plant (charas, bhaang, ganja & hashish)
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