Introduction to Pharmacology/High School (Nurse)

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Pharmacology deals with:

  • pharmacodynamics − the mechanisms and effects of drugs → what a drug does to an organism,
  • pharmacokinetics − the fate of drugs in the body (absorption, distribution, metabolism, excretion).

For didactic reasons, we divide pharmacology into:

  • general pharmacology
  • special pharmacology

General pharmacology[edit | edit source]

Defines, on the basis of experiments, the generally valid laws manifested in the interaction between the organism and the pharmaceutical. Its knowledge is a prerequisite for understanding special pharmacology.

Special pharmacology[edit | edit source]

Classifies drugs in terms of pharmacodynamics. It studies the properties of drugs in their specific form. Examines and determines their pharmacokinetics.

Recipes[edit | edit source]

A set of basic provisions that must be followed when handling and creating a prescription.

Medicinal forms[edit | edit source]

Drug Elimination[edit | edit source]

  • more about on Elimination of drugs
  • Determined by the chemical properties of the substance of interest.
→ water-soluble substances can be eliminated relatively quickly by the kidneys (PNC)
→ fat-soluble drugs are poorly excreted in urine → require transport binding to proteins (e.g. plasma albumin) that are not present in urine → lipophilic drugs require conversion to more hydrophilic metabolites, i.e. are biotransformed

Biotransformation - metabolism[edit | edit source]

  • Processes occurring predominantly in the liver that are mediated by a number of enzymes.
  • Two phases:
Phase I reactions → change in drug structure (oxidation, reduction, hydrolysis).
  • Enzymes of the cytochrome P450 family. A metabolite often retains some liposolubility.
Phase II reactions → conjugation reactions, such as binding to glucuronic acid, sulfuric acid, or glycine → metabolites with larger molecules and good water solubility to allow hepatic and renal elimination.

Excretion[edit | edit source]

  • I.e. the removal of a substance from the internal environment of the body.
  • It takes place mainly in the liver and kidneys, less significantly in the lungs, intestine, salivary and sweat glands, etc.
  • Binding during excretion by the liver is substrate specific, therefore drug-drug interactions may occur when multiple drugs are administered simultaneously.

Distribution[edit | edit source]

  • Means the penetration of the drug from the systemic circulation into the tissues.
  • The process of distribution is strongly influenced by the properties of the administered substance.
  • For example, highly lipophilic drugs rapidly penetrate barriers and therefore tend to rapidly escape from the circulation and concentrate in tissues.
  • Hydrophilic drugs are unable to penetrate barriers and remain predominantly in the blood or extracellular fluid (see below).

Volume of distribution - Vd[edit | edit source]

Receptors[edit | edit source]

  • Receptor mechanisms → the substance acts through a receptor, i.e. protein macromolecules with which it reacts and thereby induces a cellular response,
→ when endogenous or exogenous regulatory substances interact, they trigger a series of events that manifest themselves as a phamacological effect.
  • Affinity - characterizes the ability of a substance to bind at a given concentration to a given receptor.
  • Intrinsic activity - the ability of an attractant to elicit an effect.
  • Agonist - binds to a receptor and produces an effect by interacting with it. (Full agonist = 100% effect)¨¨
  • Partial agonist - has little agonist effect when acting alone, competitively antagonizes their effect when acting with stronger agonists.
  • Antagonist - inhibits the effect of agonists but has no effect on its own.
  • Reversibly interacting antagonists are referred to as competitive antagonists (they have relatively high affinity but very low intrinsic activity).
  • Non-competitive antagonists either bind irreversibly to the receptor while having very low intrinsic activity or inhibit the signal transduction induced by the agonist.

Non-receptor mechanisms[edit | edit source]

  • Influenced by the chemical properties of substances or their interaction with other protein molecules, e.g. in body fluids.
  • These include:
  • Increase in substrate supply (e.g., used to treat Parkinson's disease),
  • administration of a false precursor (e.g., α-methylnoradrenaline instead of NA is formed at the terminals),
  • Blockade of bioactive substance degradation (e.g., inhibition of a Physostigmine leading to acetylcholine accumulation; also e.g., inhibition of MAO),
  • affecting DNA function (cytostatics),
  • action of antibiotics and chemotherapeutics (affecting metabolism and function of the micro-organism).

Doses[edit | edit source]

Changes with repeated administration[edit | edit source]

  • more about on Tachyphylaxis
  • more about on Tolerance
  • After repeated administration, allergy may occur on immunological grounds.

Drug interactions[edit | edit source]


Links[edit | edit source]

External links[edit | edit source]

Sources[edit | edit source]

  • MUDR. PETR VOJTÍŠEK, . Základy farmakologie [lecture for subject Modul Algeziologie, specialization Sestra pro intenzivní péči – postgraduální studium, Vyšší odborná škola zdravotnická škola Střední a vyšší zdravotnická škola Ústí nad Labem]. Ústí nad Labem. 11.11. 2011.