Unit-I General Pharmacology Pharmacology-I

    

1)General Pharmacology

a) Introduction to pharmacology 

Pharmacology:

To study about the drugs Pharmacon (Drug) + Logy(Study)

• It is the branch of science which deal with the study of Pharmacodynamics and Pharmacokinetics.
• It is all about study about study of drug and effect of drug on body and body's response for the drugs.

(i) Pharmacodynamics : pharmaco - drugs , Dynamics- effects

    The branch of pharmacology concerned with the effect of drugs and the mechanism of their action

(ii) Pharmacodynamics: The branch of pharmacology concerned 

Definition:-

(i) Pharmacology: it is the branch of the science which deal with the study of uses, effects and mode of action of drugs.

(ii) Clinical Pharmacology: study of the drugs with their clinical uses.

(iii) Drugs: a medicine or other substance which give therapeutic effect when ingested into body.

(iv) Pharmacokinetics: it is a branch of pharmacology concern with the movement of drug in body or study about (ADME) adsorption distribution metabolism excretion of drug in body.

(v) Pharmacodynamics: it is a branch of pharmacology concerned with the effect of drug on body (what does drug do to the body)

(vi) Toxicology: the branch of science concern with the study of the poisons, toxic substances and their antidote or treatment.

(vii) Chemotherapy-it is the branch in which we study about the use of chemical drugs for the disease (effect of drugs).

(viii) Adverse reaction: in Pharmacology, any unexpected or dangerous reaction to a drug.

An unwanted if it caused by the administration of a drug.

(ix) Bioavailability: it is defined as, "the rate and extent to who is the active substance absorbed from a pharmaceutical from and becomes available at the site of action.

 

Historical Landmarks 

• The knowledge of drugs and their uses for disease are old as history of mankind.
• Primitive man(Ancient) gather the knowledge of healing and medicines by observing the nature, noticing the animals while ill and personal experience  after consuming plants and herbs as remedies.
• They discovered that extracts from plants, animals and minerals had medicinal had medicinal effects on body tissue.

Landmarks: 

• Hippocrates(460-375BC) A Greek physician consider "father of Medicines".
• He was the first person who recognize disease as abnormal reaction of body.
• He introduce use of metallic salts for the treatment of disease
• Paracelsus(1493-1541) Grandfather of pharmacology he introduces the use of chemicals for treatment of disease

Modern Pharmacology

• Oswald Schmiedeberg(1838-1921)- Father of pharmacology
• He established pharmacology as an independent discipline.
• estimation of chloroform in blood.
• John Jacob Abel (1857-1938)

• Isolation of histamine from pituitary.
• Preparation of pure crystalline. 
•  Paul Enrich(1854-1915
• Paul Enrich was a Nobel prize winner - Father of chemotherapy.
• Find a cure for syphilis in 1909 (used arsenical for syphilis).
• Alexander Fleming (881-1955)
• Scottish physician.
• He discovered world's first broadly effective antibiotic substance which he named penicillin.

• Ramnath Chopra(1882-1973)
• He was an Indian medical service officer(IMS).
• Father of Indian Pharmacology.
• System study of Indian medicinal Plant.

  

Scope Of Pharmacology

• Study  about drugs and their actions.
• Study about disease or disorder which is comes under pathophysiology.
• Study about Pharmacodynamics, what is the effects of drug to the body in which study about both desirable and undesirable effects of Drug 
• Study about Pharmacokinetics, what does body to do the drug(ADME).
• So, In present time their are many scopes  in pharmacology such as research, Industries and  academics etc.
• Study of clinical Pharmacology, in which we study contraindication of drugs, their Bioavailability and also about posology.
• Study of forensic science
• Their are also great scope of Pharmacology in research such as, Drug development, Drug discovery and clinical trials.
• Drug development:- Development of new drugs or discovery for new drugs 
• then clinical trials first is pre clinical(according to their phase) trials(drugs applied on animals) then second trials for humans if suitable or pass in pre-clinical trials.
• Pharmacogenomics:- It is use of genetic information to guide the choice of drug & dose it helps in drug discovery and minimize adverse drug reaction.
• Pharmacogenetics: It is study of genetic basis for variability in drug response, it also helps in development  of drugs 
• Pharmacology is the Backbone of Medicine

Nature And Sources of Drugs

1) Nature of Drugs:

    All drugs are chemical entities with simple or complex molecules 

• Inorganic drugs- some drugs are of inorganic nature, e.g. Ferrous sulphate, Lithium carbonate etc.
• Organic drugs:- Majority of drugs are of organic compounds it may be 
• It may be - weakly acidic (aspirin, penicillin) or weakly basic (basic), or non-electrolytes (alcohols etc )
• Mostly drugs are normally solids, e.g. Paracetamol, ampicillin etc. but liquids, and few like nitrous oxide are gaseous.
• the molecular weight of majority of drugs in the range of 100-100D

=According to their action:-

• Presentive:- These drugs which used to present the cause of the disease.
• Symptomatic: Those drugs which used to treat the symptom of that disease.
• Diagnostic:- Those drugs which helps to determine the treatment or causes of disease.
• Curative: Those drugs which used in treatment of any disease 
• Health Maintenance: Those drugs which help to maintain our health.

2) Source Of Drugs:-

• Plants:-Many plants contain biologically active substances and are the oldest sources of drugs.    
• E.g. Tulsi(Used for cough treatment &cold  remedies), Neem(antimicrobial activity)
• Animals:-Though animal parts have been used as cured since early times                                       
• Used for making vaccines.         
• Used of insulin for control diabetes.
• E.g. Thyroxine, insuline, Liver extracts(vit.B12)
  
• Microbes:-Most antibiotics are obtained from fungi, Bacteria etc.
• e.g. Penicillin, bacteria etc.
• Some times vaccines are also produced by the use of microbes.
• Minerals:-their are many more minerals which is used as a medicinal substances
• e.g. Iron(Anemia), Zinc(Wound healing), Iodine(Antiseptic), Silver (Immunity booster ) etc.
• Synthetic:- It is the largest sources of medicines
• It has the advantages of purity and uniformity of the product, they can be manufactured as per need.
• e.g. fluoroquinolones, Bismuth iodine etc.
• Biotechnology:- In which, combined biological organism with technology and generate new drugs.
• e.g peptides are now produce by recombined DNA Technology.
• Human growth hormone 
• Human Insulin.

Essential Drug Concepts and Routes of drug administration

WHO (WORLD HEALTH ORGANIZATION)  Introduced the concept of essential of essential medicines(drug) in1977. [ included 208 medications] 

• Definition:- Thses are those drugs which satisfy the priority health care needs of the population
• Criteria:- They are selected with due regard to:-
• Public health relevance.
• Clinical evidence on efficacy and safety 
• Comparative cost effective [individual & community can afford] 
• Available at all time in adequate amount 
• Appropriate dosage form
• Assured quality and adequate information.
• India proposed its first list in 1996, and has revised it in 2011, and now in April 2015 with  the title name "national list of essential medicines". [includes 376 medicines]
• The WHO Updates the list in every two Years.
• It can be differ from country to country due to change their environment.
• e.g. 
• Acetylsalicylic acid(Aspirin)
• Paracetamol
• Ibuprofen
• Morphine etc.
• Activated Charcoal used as a Antidote

Routes of Drug Administration

A route of administration in pharmacology is the path by which a drug/medicine or any other substance is taken into the body.

Classification:- On the basis of their location, they can be classified as:- 

1.Local Routes   

  It is the  simplest route, in which drug is applied only on a particular area or directly on a site of action.

• Topical route In this, drug is  applied externally on the surface of skin and give localized action.
• Advantages:
• Apply for local action.
• More convenient as well as encouring to patient.
• Painless, safe, cheap, useful for childs.
• Disadvantages
• Slow action
• Same Drugs cause irritation
• Drug can be efficiently delivered to the localized lesion on skin, in the form of lotion..
•  Inhalation /Nasal

    It also a part of systemic circulation, in which drug is inhaled through blood through blood capillaries present in mucosa/muscles(rapid absorption & effects)

E.g. Asthma used as a bronchodilators

• Rectal/Vaginal
•     In which, Special types of drug preparation is injected into rectum and vagina to give their local action on it 
• Also some part is absorbed in systemic circulation so it is also include in systemic.
• E.g. suppositories, or Enema etc.
• Advantages
• Given to unconscious patients.
• Ideal if drug cause vomiting.
• Disadvantages
• Cause irritation
• not a well accepted.
• Auricular(Ear/eyes/ear cannel)
• In this, drug is introduced into body cavity like ear, eye, and produce a local effect in it
• Eg, drops, ointment and sometimes suspensions.

2.Systemic Routes

In which, the drug administered through systemic routes means absorbed into the blood stream and distributed all over, including the site of action.

• Enteral:- It means through intestinal. In which drug pass through intestine then reach into blood 
• It shows First pass metabolism
• First Pass Metabolism:- In which drug directly goes into liver after intestine through portal vein, in which drug metabolize and their bioavailability will be decrease
• Oral route: It is the oldest and simplest method for drugs adminstration0. in which drugs  is directly swell through mouth and it reach in systemic by passing G.I.T.
• Both solid dosage form(powders, Tablets, Capsules etc..) and liquid dosage form(elixirs, syrups, emulsions etc.) can be given orally.
• Advantages:-
• safe, more convenient, does not need assistance 
• Painless, cheap & cost effective
• Easily Available
• Disadvantages:- 
• Slow responses due to first pass metabolism
• Not suitable for emergencies
• Cannot be used for unconscious patients
• Parental :- par-beyond, Enteral- Intestinal.
• In this drug is reaches into blood stream other than intestinal routes.
• It follow Bypass metabolism
• Bypass Metabolism:- In which drug directly reaches into blood then reach at site of action through circulation without passing intestine &Liver
• Sublingual/Buccal route: It may be in the part of enteral.
• The tablet or pellet containing the drug is placed under the tongue/ crushed in the mouth and spread over the mucosa, which further absorbed into the blood.
• only lipid soluble drug can be administrated; also  it is on-irritating.
• Advantages:-
• Rapid action.
• It follows bypass metabolism.
• Disadvantages:-
• Inconvenient for patient.
•  Injections: