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Elaboration on lectures, Physiology and PharmacologyLecture 1 Introduction Pharmacology Part 1, Schmidt
Medicinal drugs that are important to learn are the active substances, these substances are approved
and harmless. The dosage has an effect for a maximum of one hour, individuals that take medicine
should preferably not participate in activity. This is true for the following substances:
Adrenaline
Propranolol
Prazosin
Nicotine
Placebo
Digoxin
Carbachol
Atropine
Pharmacology is the treatment of diseases, this can be in the cardiovascular system, such as heart
failure and hypertension (high blood pressure), the respiratory system, such as bronchial asthma and
COPD (loss of lung tissue), the endocrine pancreas, such as diabetes mellitus and a metabolic
syndrome.
Pharmaceuticals = medicinal drugs
Physiology studies the function of the body, regarding homeostasis, integrative physiology and
pathophysiology.
Until late into the 19th century diseases were treated with natural products that were obtained from
living and inanimate things, these has a healing and thus therapeutic effect, but there were also
substances with a toxic effect. Morphine was for example isolated from a plant, it has a analgesic
effect. From this morphine codeine is made and which is a cough syrup. This action takes place via
receptors which means that it are proteins.
Pharmaceuticals are isolated in order to:
Identify the active substance
Determine the pharmacodynamics (analysis of the biological effect) and the
pharmacokinetics (analysis of their ‘fate’ in the body).
Guarantee the exact and unchanged dose is preserved using the isolated pharmakon in
treatments.
Option of chemical synthesis (making the chemical more favourable because of the change in
pharmacological characteristics).
Altering the chemical structure (medicinal drugs that have a stronger effect).
Pharmacokinetics: regards ADME: Absorption, Distribution, Metabolism and E. The absorption
happens after the drug is administered. The most favourable way of administering a drug are oral
administration and inhalation. Oral administration does need to take into a count that there is a first
pass effect and that the pH of the stomach is low. It does however have a high patient compliance.
Inhalation can be done using the respiratory system the main advantage of this is the low systemic
load. The administration and distribution can be done various ways, also topical (at site of action) and
via injection are options. Some ‘pro’-drugs are activated in the liver and will then be activated
substances. Blood-tissue barriers need to be taken into a count, the polarity and charge of
pharmaceuticals determine if it has a central effect (blood-brain barrier can be crossed, permeable)
or a peripheral effect (blood-brain barrier cannot be crossed, impermeable). Normally the blood-
,brain barrier cannot be crossed, only a drug with a transporter or a drug that is lipophilic. Of the
plasma proteins Albumin is one of the most abundant ones. Albumin has a low affinity for the active
substance (drug) of the plasma protein. The affinity for specific binding sites, such as receptors, is
high. The binding sites of the albumin are far from saturated and a medicinal drug-protein complex
will result in no effect from the medicinal drug. The drug either binds to albumin or to the specific
binding receptor. Elimination can already happen before the drug is active, this is due to the first-
pass effect. High presystemic elimination can be desirable in certain therapeutic situations, so it is
not necessarily a bad thing. Propranolol is used when heart and vessel functions need to be altered -
> this will most likely result in a high first-pass effect.
Development of medicinal drugs are developed in pharmacological studies or clinical
pharmacological studies. There are a number of candidate substances that might work as a drug but
these need to be approved and harmless.
A drug can have side effects, however a right dose makes the difference between a poison and a
remedy. A substance in itself is never toxic however, when overdosed any substance can be toxic.
Increased sensitivity will cause diseases and chronic diseases require repeated administration.
Physiology studies the heart rate, blood pressure and ECG as well as the effects of exertion. Whilst
pharmacology studies the effects of medicinal drugs on the cardiovascular system.
Some effects that do not involve medicinal drugs are found in the human behaviour.
Digoxin is used to treat cardiac oedema (heart failure), active substances are always steroids that are
bound to C3 with one or more sugar molecules.
Atropine is used as a cosmetic, as eye drops. It helps relax the muscles in the eye. It is currently the
most important substance among the competitive antagonists of the muscarinic acetylcholine
receptors.
Effects of medicinal drugs are classified by a quantification:
EC: effective concentration
Emax: maximum possible effect
EC50: effective concentration to achieve 50% of the biological effect.
Lecture 2 Introduction Pharmacology Part 2, Schmidt
The number of binding sites that are free and available to respond decreases as the saturation of the
binding sites increase. Then the increase in binding no longer corresponds to the increase in
concentration.
The characteristics of receptor-binding experiments:
Saturability
Specificity
Binding affinities
NO discrimination between agonist and antagonist.
Agonist will induce an active conformation of
the receptor protein whilst the antagonist
only occupies the receptor without any
effects. An agonist causes intrinsic activity and
an antagonist no intrinsic activity. Antagonist
selects inactive receptor conformation whilst
an agonist selects active receptor
conformation. Agonist A in the picture has a
, higher efficacy than agonist B and reaches the maximum efficacy, agonist A is therefore a full agonist
and agonist B a partial agonist. The use of an agonist will cause a biological response. The use of an
antagonist will lead to no response and will prevent an agonist from binding to the receptor. Agonist
(mimetic drug) will bind to a receptor due to its affinity and will cause the stimulus of a cellular
response due to the efficacy of that agonist. An antagonist (blocker, lytic drugs) will bind to a
receptor due to its affinity will but will not cause a cellular response. It will also block or supress the
effect of the agonist. In order for an antagonist to work an agonist needs to be present.
There are different classes for antagonists
as visible on the picture. An antagonist can
be competitive or can be non-competitive.
When an agonist binds to the receptor a
conformatial change can be put in motion.
But when this agonist has a competitive
antagonist this antagonist might bind to the
receptor and will cause this change to be
undone. An allosteric antagonist binds to an
allosteric site which will block the effect
from the agonist disregarding the agonist,
that might have been bound. The non-competative antagonist has a different binding place than the
agonist which causes the receptor to disfunction anyhow. Pharmaceuticals (medicinal drugs) is
competitive antagonism. When an agonist acts alone this will have a quicker response time in
comparison to an agonist coupled with an antagonist, this is only valid when the antagonist is a
competative antagonist. When a noncompetitive antagonist is used only half of the effect that the
agonist would cause is reached. Because half of the receptors is blocked with this noncompetitive
antagonist. When the antagonist is used alone there will be no response in either of the examples.
Smooth muscle cells in the airways will contract when acetylcholinie binds to an M3 receptor.
Adrenaline will bind to the Beta2 receptor, this will cause ATP to form cAMP which will cause
relaxation in the smooth muscle cells in the airways. Antagonistic neurons control heart rate: some
speeds it up, while others slow it down. Parasympathetic stimulation will cause a decrease in heart
rate while the sympathetic stimulation causes a increase in heart rate.
Cell function can be influenced by pharmaceuticals, neural control, hormonal control, cellular
transport or direct action can be used to transfer a drug into the cell.
There are different receptor types that
have a unique time scale. The ligand-
gated ion channels react when a
agonist binds to the receptor. This will
cause hyperpolarisation or
depolarisation. The ligand-gated ion
channels consist of 5 subunits. Two
acetylcholine molecules or nicotine
molecules can bind in order for the
channel to become active. The
activation will cause Na to be pumped
in the cell and K out of the cell.
Nicotinic acetylcholine receptors can be found on the muscles or on neurons.
G protein-coupled receptors consist of an membrane protein that activates a G-protein that will
activate an effector protein which will lead to the desired effect. There are two types of receptors:
Muscarinic ACh receptors: M1, M2, M3, M4, M5. Adrenoceptors: α1, α2, β1, β2, β3. On the receptor
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