In early days drugs were mostly derived from plants, even today extracts of plant tissues are employed to some extent e.g. Eucalyptus oil. The word 'drug's is derived from the French word, 'drogue which means 'dry hurb'. In this article, we will discuss in details about the pharmaceutical industry.
Drugs ate defined in number of ways;
A drug is a chemical substance that has known biological effects on human or other animals.
A drug is a chemical substance used in the treatment, cure, prevention or diagnosis of disease or used to otherwise exchange physical or mental well-being. Pharmaceutical drugs may be used for a limited duration or on regular basis for chromic disorder.
These are chemical substances that effect the function of the nervous system, altering perception, mood or consciousness. e.g. Alcohol, Nicotine and Caffeine are the most widely consumed psychoactive drugs worldwide.
These are drugs that are not used for medicinal purposes, but are instead used for pleasure. Common recreational drugs include alcohol, nicotine and caffeine, as well as other substances such as Opiates (one of several drugs, derived from opium and including morphine and codeine) and amphetamines.
Many drugs are illegal for recreational purposes and international treaties such as the single convention on Narcotic. Drugs exist for the purpose of legally prohibiting certain substances.
A drug is a substance with an abnormal effect on certain body functons, e.g.strichine stimultes the action of heart where as excessive dose of aspirin stops the action of heart.
It is well known fact that many diseases are caused by invanding pathogenic organisms like bacteria, protozoa, viruses, fungi etc. A chemical which is capable of controlling the infection caused by such micro-organisms is called Chemotherapeutic agent, provided it is not toxic to the infected host.
Many compounds, e.g. formaldehyde, phenol, iodine etc. are also capable of destroying bacterial, but they tend to destroy the tissues of the host. Hence, these compounds are always used externally and that is why these compounds are not included under the heading of therapeutic agents. Such compounds are known as disinfectants.
The therapeutic properties of compounds depend upon their relative toxicity to the parasite and the host. It should be highly toxic to the invanding micro-organisms and least toxic to the host. The ratio of the amount of drug necessary to kill the patient to that required for a maximum curative dose, is known as therapeutic index. The medical value of the drugs is generally represented by therapeutic index, which may be expressed as,
Therapeutic index = MTD/MCD ;
where, MTD= Maximum tolerated dose
And MCD =Maximum curative dose.
A therapeutic index 10 means that, ten times a dose used for curative purpose would kill the patient as well as parasite.
Drugs can be classified according to various criteria including chemical structure or pharmaceutical action. The preferred classification is the latter one which may be divided into main three groups as follows:
Chemotherapy deals with the use of chemical agents in the treatment of infectious diseases. The substances so employed are called chemotherapeutic agents.
These agents are designed to kill the invanding organisms without harmful effects upon the host. e.g. Sulpha drugs, antibiotics, antiseptics, anti-inflammatory drugs, anti-malerials, anti-fungal, anti-neoplastic drugs, anti-tubereular and anti-leprocy drugs, organo metallic compounds.
These are the drugs which act on the various functions of the body. They stimulate or depress various functions of the body so as to provide relief from symptoms of discomfort.
Although these agents have a characteristic effect on the animal, they are not specific remedies for particular diseases. These agents are mainly used in case of non-infectious diseases to correct abnormal functions. e.g. Cholinergic, Adrenegic, Anti-histamines and antipyretics, diuretics, tranquilizers, cardiovascular agent etc.
These drugs are specific for particular organ. e.g. Narcotic analgesics, local anesthetics.
Drugs have three or more names:
The chemical name is assigned to rules of nomenclature of chemical compound.
The brand or trade name is always capitalized and is selected by the manufacturer.
The genetic name refers to a common established name irrespective of its manufacturer.
In most cases, a drug bearing a genetic name is equivalent to the same drug with a brand name. However, this equivalency is not always true. Although drugs are chemically equivalent, different manufacturing processes may cause differences in pharmacological action. Several differences may be crystal size or form, isomers, crystal hydration, purity, vehicles, binders, coatings, dissolution rate and storage stability.
The action of drugs on the human body is called pharmacodynamics and what the body with the drug is called pharmacokinetics. The drugs that enter the human body tend to stimulate certain receptors, ion channels, act on enzymes or transporter proteins. As a result, they cause the human body to react in a specific way.
Many cells have specialized areas, known as receptors, on their outer walls. Natural chemical messengers, such as hormone, bind with these receptors to produce changes in cells and thereby affect body processes. In order to treat some disorders, it may be necessary to increase or decrease the effect of a particular natural chemical.
There are two different types of drugs:
These drugs bind with specific receptors to produce an effect similar to that of the natural chemical. They stimulate and activate the receptors. An agonist drug mimics the action of body chemicals. It occupies an empty receptor and enhances the natural chemicals effect.
An antagonist drug occupies cell receptors, preventing the body chemicals from binding to them, thereby inhibiting their action. They stop the agonists from stimulating the receptors.
Once the receptors are activated, they either trigger a particular response directly on the body, or they trigger the release of hormones and or other endogenous drugs in the body to stimulate a particular response.
Drugs interact with receptors by bonding at specific binding sites. Most receptors are made up of protein, and the drugs can therefore interect with amino acids to change the conformation of the receptors protein. These interactions are very basic, just like that of other chemical bonding.
There are many isomers of a particular drug, and each one will have its own effects. Differences in isomer affect not only what drug activates, but also changes the potency of each drug.
Following factors affect the drug action:
It is a measure of how much a drug is required in order to produce a particular effect. Therefore, only a small dosage of a high potency drug is required to induce a large response.
Drug companies invest significant effort in designing drug that interact specifically with particular receptor, since non-specific drugs can cause more side effects.
Example: The endogenous drug acetyl choline is used by the para-sympathetic nervous system to activate muscarinic receptors and by neuro-muscular system to activate nicotinic receptors. However, the compounds Muscarine and nicotine can each preferentially interact one of the two receptors types, allowing them to activate only one of the two systems where ACh itself would activate both.
Affinity of a drug is a measure of how tightly a drug binds to the receptors. If the drug does not bind well, then the action of the drug will be shorter and the chance of binding will also be less.
Drug metabolism is the process by which the body breaks down and converts medication into active chemical substances.
1) The primary site of drug metabolism is the liver, which plays a major role in metabolism, digestion, de-toxification and elimination of substances from the body.
2) Enzymes in the liver are responsible for chemical changing drug components into substances known as metabolites.
3) Metabolites are then bound to other substances for excretion through the lungs or bodily fluids such as saliva, sweat, breast milk, and urine or through re-absorption by the intestines.
4) Excretion: The primary mode of excretion is through the kidneys.
5) Crypto chrome P-450: The family of liver isoenzymes known as cytochrome P-450 are crucial to drug metabolism. These enzymes have catabolic action on substances,breaking them down into metabolites. Consequently, they also act to lower the concentration of mediation in the blood stream.
6) Action of P-450: Drug intereactions can occur when one drug inhibits or induces a P-450 that acts on another drug. e.g. nicotine, a drug contained on tobacco, and known to induce P-450 s. Individuals with liver disease may also have insufficient levels of P-450 enzymes. As a result, the concentration of drugs metabolized by these enzymes remains high and can build up to toxic levels in the bloodstream.
7) Remidy: Certain medications and foods, such as grapefruit juice, can inactivate or lesson the metabolic activity of P-450s. Changing the dosage can alleviate the problem in some cases.
8) Other factors: a) The metabolic rate can vary significantly from person to person, and drug dosages that work quickly and effectively in one individual may not work well for another.
b) Factors such as generics, environment, nutrition, and age also influence drug metabolism, infants and elderly patients may have a reduced capacity to metabolize certain drugs, and may require adjustment in dosage.
Methods of Production of drugs:
Drug manufacturing is the process of industrial scale synthesis of pharmaceutical drugs by pharmaceutical companies. The process of drug manufacturing can be broken down into a series of unit operations, such as - milling, graduation, coating, tablet pressing, and others.
Milling is often required in order to reduce the average particle size in a drug powder. This step is essential for increasing homogenaity and dosage uniformity, increasing bioavailability, and increasing the solubility of the drug compound.
Granulation can be throught of as the opposite of milling. Granulation is the process by which small particles are bound together to form large particles called granules.
Granulation is used for several reasons. It prevents the 'demixing' of components in the mixture, by creating a granule which contain all of the components in their required proportions, improves flow characteristics of powders (because small particles do not flow well), and improves compaction properties for tablet formation.
In pharmacology, biological activity or pharmacological activity describes the beneficial or adverse effects of a drug on living matter, when a drug is a complex chemical mixture, this activity is exerted by the substance's active ingredient or pharmacophore but can be modified by the other constituents.
Among the various properties of chemical compounds, pharmacological activity plays a crucial role, since it suggests use of the compounds in the medical applications. However, chemical compounds may show some adverse and toxic effects which may prevent their use in medical practice.
1) Pharmacological activity is generally dosage-dependent.
2) It is common to have effects ranging from beneficial to adverse for one substance when going from low to high doses.
3) Activity depends critically on fulfillment of the ADME (Absorption, Distribution, metabolism, and Excretion).
4) To be an effective drug, a compound not only must be active against a target, but also possess the appropriate ADME properties necessary to make it suitable for use as a drug.
5) A material is considered bioactive if it has intereaction with or effect on any cell-tissue in the human body, pharmacological activity is usually taken to describe beneficial effects i.e. the effects of drug candidates as well as a substance's toxicity.
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| Pharmaceutical industry |
Definition of drugs:
Drugs ate defined in number of ways;
1) In the broadest term:
A drug is a chemical substance that has known biological effects on human or other animals.
2) In pharmacology:
A drug is a chemical substance used in the treatment, cure, prevention or diagnosis of disease or used to otherwise exchange physical or mental well-being. Pharmaceutical drugs may be used for a limited duration or on regular basis for chromic disorder.
3) Psychoactive drugs:
These are chemical substances that effect the function of the nervous system, altering perception, mood or consciousness. e.g. Alcohol, Nicotine and Caffeine are the most widely consumed psychoactive drugs worldwide.
4) Recreational drugs:
These are drugs that are not used for medicinal purposes, but are instead used for pleasure. Common recreational drugs include alcohol, nicotine and caffeine, as well as other substances such as Opiates (one of several drugs, derived from opium and including morphine and codeine) and amphetamines.
5) Addition and habituation (drug dependent) drugs:
Many drugs are illegal for recreational purposes and international treaties such as the single convention on Narcotic. Drugs exist for the purpose of legally prohibiting certain substances.
6) Most acceptable definition:
A drug is a substance with an abnormal effect on certain body functons, e.g.strichine stimultes the action of heart where as excessive dose of aspirin stops the action of heart.
It is well known fact that many diseases are caused by invanding pathogenic organisms like bacteria, protozoa, viruses, fungi etc. A chemical which is capable of controlling the infection caused by such micro-organisms is called Chemotherapeutic agent, provided it is not toxic to the infected host.
Many compounds, e.g. formaldehyde, phenol, iodine etc. are also capable of destroying bacterial, but they tend to destroy the tissues of the host. Hence, these compounds are always used externally and that is why these compounds are not included under the heading of therapeutic agents. Such compounds are known as disinfectants.
Therapeutic Index:
The therapeutic properties of compounds depend upon their relative toxicity to the parasite and the host. It should be highly toxic to the invanding micro-organisms and least toxic to the host. The ratio of the amount of drug necessary to kill the patient to that required for a maximum curative dose, is known as therapeutic index. The medical value of the drugs is generally represented by therapeutic index, which may be expressed as,
Therapeutic index = MTD/MCD ;
where, MTD= Maximum tolerated dose
And MCD =Maximum curative dose.
A therapeutic index 10 means that, ten times a dose used for curative purpose would kill the patient as well as parasite.
Classification of drugs:
Drugs can be classified according to various criteria including chemical structure or pharmaceutical action. The preferred classification is the latter one which may be divided into main three groups as follows:
1) Chemotherapeutic agents (drugs):
Chemotherapy deals with the use of chemical agents in the treatment of infectious diseases. The substances so employed are called chemotherapeutic agents.
These agents are designed to kill the invanding organisms without harmful effects upon the host. e.g. Sulpha drugs, antibiotics, antiseptics, anti-inflammatory drugs, anti-malerials, anti-fungal, anti-neoplastic drugs, anti-tubereular and anti-leprocy drugs, organo metallic compounds.
2) Pharmacodynamic agents (drugs):
These are the drugs which act on the various functions of the body. They stimulate or depress various functions of the body so as to provide relief from symptoms of discomfort.
Although these agents have a characteristic effect on the animal, they are not specific remedies for particular diseases. These agents are mainly used in case of non-infectious diseases to correct abnormal functions. e.g. Cholinergic, Adrenegic, Anti-histamines and antipyretics, diuretics, tranquilizers, cardiovascular agent etc.
3) Miscellaneous agents:
These drugs are specific for particular organ. e.g. Narcotic analgesics, local anesthetics.
Nomenclature of drugs:
Drugs have three or more names:
a) Chemical name:
The chemical name is assigned to rules of nomenclature of chemical compound.
b) Brand or trade name:
The brand or trade name is always capitalized and is selected by the manufacturer.
c) Genetic or Common name:
The genetic name refers to a common established name irrespective of its manufacturer.
In most cases, a drug bearing a genetic name is equivalent to the same drug with a brand name. However, this equivalency is not always true. Although drugs are chemically equivalent, different manufacturing processes may cause differences in pharmacological action. Several differences may be crystal size or form, isomers, crystal hydration, purity, vehicles, binders, coatings, dissolution rate and storage stability.
Action of Drugs:
The action of drugs on the human body is called pharmacodynamics and what the body with the drug is called pharmacokinetics. The drugs that enter the human body tend to stimulate certain receptors, ion channels, act on enzymes or transporter proteins. As a result, they cause the human body to react in a specific way.
Many cells have specialized areas, known as receptors, on their outer walls. Natural chemical messengers, such as hormone, bind with these receptors to produce changes in cells and thereby affect body processes. In order to treat some disorders, it may be necessary to increase or decrease the effect of a particular natural chemical.
Types of Drugs:
There are two different types of drugs:
a) Agonist drugs:
These drugs bind with specific receptors to produce an effect similar to that of the natural chemical. They stimulate and activate the receptors. An agonist drug mimics the action of body chemicals. It occupies an empty receptor and enhances the natural chemicals effect.
b) Antagonist drugs:
An antagonist drug occupies cell receptors, preventing the body chemicals from binding to them, thereby inhibiting their action. They stop the agonists from stimulating the receptors.
Once the receptors are activated, they either trigger a particular response directly on the body, or they trigger the release of hormones and or other endogenous drugs in the body to stimulate a particular response.
Drugs interact with receptors by bonding at specific binding sites. Most receptors are made up of protein, and the drugs can therefore interect with amino acids to change the conformation of the receptors protein. These interactions are very basic, just like that of other chemical bonding.
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Drugs interaction |
Factors affecting Drug action-
There are many isomers of a particular drug, and each one will have its own effects. Differences in isomer affect not only what drug activates, but also changes the potency of each drug.
Following factors affect the drug action:
a) Potency:
It is a measure of how much a drug is required in order to produce a particular effect. Therefore, only a small dosage of a high potency drug is required to induce a large response.
b) The specificity of drugs:
Drug companies invest significant effort in designing drug that interact specifically with particular receptor, since non-specific drugs can cause more side effects.
Example: The endogenous drug acetyl choline is used by the para-sympathetic nervous system to activate muscarinic receptors and by neuro-muscular system to activate nicotinic receptors. However, the compounds Muscarine and nicotine can each preferentially interact one of the two receptors types, allowing them to activate only one of the two systems where ACh itself would activate both.
c) Affinity:
Affinity of a drug is a measure of how tightly a drug binds to the receptors. If the drug does not bind well, then the action of the drug will be shorter and the chance of binding will also be less.
Metabolism of drugs:
Drug metabolism is the process by which the body breaks down and converts medication into active chemical substances.
Process of metabolism:
1) The primary site of drug metabolism is the liver, which plays a major role in metabolism, digestion, de-toxification and elimination of substances from the body.
2) Enzymes in the liver are responsible for chemical changing drug components into substances known as metabolites.
3) Metabolites are then bound to other substances for excretion through the lungs or bodily fluids such as saliva, sweat, breast milk, and urine or through re-absorption by the intestines.
4) Excretion: The primary mode of excretion is through the kidneys.
5) Crypto chrome P-450: The family of liver isoenzymes known as cytochrome P-450 are crucial to drug metabolism. These enzymes have catabolic action on substances,breaking them down into metabolites. Consequently, they also act to lower the concentration of mediation in the blood stream.
6) Action of P-450: Drug intereactions can occur when one drug inhibits or induces a P-450 that acts on another drug. e.g. nicotine, a drug contained on tobacco, and known to induce P-450 s. Individuals with liver disease may also have insufficient levels of P-450 enzymes. As a result, the concentration of drugs metabolized by these enzymes remains high and can build up to toxic levels in the bloodstream.
7) Remidy: Certain medications and foods, such as grapefruit juice, can inactivate or lesson the metabolic activity of P-450s. Changing the dosage can alleviate the problem in some cases.
8) Other factors: a) The metabolic rate can vary significantly from person to person, and drug dosages that work quickly and effectively in one individual may not work well for another.
b) Factors such as generics, environment, nutrition, and age also influence drug metabolism, infants and elderly patients may have a reduced capacity to metabolize certain drugs, and may require adjustment in dosage.
Methods of Production of drugs:
Drug manufacturing is the process of industrial scale synthesis of pharmaceutical drugs by pharmaceutical companies. The process of drug manufacturing can be broken down into a series of unit operations, such as - milling, graduation, coating, tablet pressing, and others.
1) Milling:
Milling is often required in order to reduce the average particle size in a drug powder. This step is essential for increasing homogenaity and dosage uniformity, increasing bioavailability, and increasing the solubility of the drug compound.
2) Granulation:
Granulation can be throught of as the opposite of milling. Granulation is the process by which small particles are bound together to form large particles called granules.
Granulation is used for several reasons. It prevents the 'demixing' of components in the mixture, by creating a granule which contain all of the components in their required proportions, improves flow characteristics of powders (because small particles do not flow well), and improves compaction properties for tablet formation.
Pharmacological Activity of drugs:
In pharmacology, biological activity or pharmacological activity describes the beneficial or adverse effects of a drug on living matter, when a drug is a complex chemical mixture, this activity is exerted by the substance's active ingredient or pharmacophore but can be modified by the other constituents.
Among the various properties of chemical compounds, pharmacological activity plays a crucial role, since it suggests use of the compounds in the medical applications. However, chemical compounds may show some adverse and toxic effects which may prevent their use in medical practice.
1) Pharmacological activity is generally dosage-dependent.
2) It is common to have effects ranging from beneficial to adverse for one substance when going from low to high doses.
3) Activity depends critically on fulfillment of the ADME (Absorption, Distribution, metabolism, and Excretion).
4) To be an effective drug, a compound not only must be active against a target, but also possess the appropriate ADME properties necessary to make it suitable for use as a drug.
5) A material is considered bioactive if it has intereaction with or effect on any cell-tissue in the human body, pharmacological activity is usually taken to describe beneficial effects i.e. the effects of drug candidates as well as a substance's toxicity.
