DOPAMINE
INTRODUCTION:-
• Dopamine is an endogenous catecholamine that serve as both a neurotransmitter and a
precursor of nor epinephrine synthesis.
• When given as an exogenous drug dopamine activates a variety of receptors in dose
dependent manner.
• Regulates cardiac, vascular and endocrine function.
Pharmacokinetic parameters:-
• Absorption;
• Following IV administration
• Onset of action is 2 min
• Peak plasma cons. of drug is 10 min after initiation of an IV infusion.
• Distribution;
• Metabolism; ( in liver)
MECHASIM OF ACTION:-
• The adrenergic drugs aXect receptors that are stimulated by norepinephrine
(noradrenaline) or epinephrine (adrenaline). These receptors are known as adrenergic
receptors or adrenoceptors. Adrenergic drugs that activate adrenergic receptors
are termed sympathomimetics, and drugs that block the activation of adrenergic receptors
are termed sympatholytics.
• Adrenergic neurons release norepinephrine as the primary neurotransmitter.
These neurons are found in the central nervous
MECHASIM OF ACTION:-
• Dopamine occurs naturally in the CNS in the basal ganglia, where it functions as a
neurotransmitter. Dopamine can activate a- and §- adrenergic receptors. For example,
at higher doses, it causes vasoconstriction by activating a1 receptors (These
receptors are present on the postsynaptic membrane of the elector organs),
whereas at lower doses, it stimulates §1 cardiac receptors. In addition,
Therapeutic uses:-
• Dopamine is the drug of choice for cardiogenic (is a state where the heart has been
damaged to the point where it is unable to supply enough blood to the organs of the body) and
septic shock ( is a serious condition that occurs when a body-wide infection leads to
dangerously low blood pressure) and is given by continuous infusion. It raises blood pressure
by stimulating the §1 receptors on the heart to increase cardiac output and a1 receptors on
blood vessels to increase total peripheral
Adverse effects::-
• Dopamine is rapidly metabolized, and its adverse effects (nausea, hypertension, and
arrhythmias) are therefore, short-lived.
PRECAUTIONS:-
• Before dopamine is administered to pt in shock ,hypovolemia should be corrected by
transfusion of whole blood, plasma or other appropriate fluid
DOBUTAMINE
Pharmacokinetic:-
• Absorption;
• Following IV administration
• Onset of action is 2 min
• Peak plasma conc. of drug is 10 min after initiation of an IV infusion
• Distribution; well distributed throughout the body tissues
• Metabolism; ( in liver)
MECHANISM OF ACTION:-
• Dobutamine is a direct-acting agent whose primary activity results from stimulation
of the §₁-adrenoceptors of the heart, increasing contractility and cardiac output. Since
it does not act on dopamine receptors to induce the release of norepinephrine (another
a₁agonist), dobutamine is less prone to induce hypertension than is dopamine.
• Dobutamine is predominantly a §₁-adrenergic agonist, with weak
§₂ activity, and a₁ selective activity, although it is used clinically in
Therapeutic use:-
Inotropic support
Congestive heart failure
Open heal surgery
stress testing
ADRs:-
Immune s stem disorders: Hypersensitivity reactions including;
Anaphylactic reactions and severe life-threatening asthmatic episodes.
Pharmacokinetics:-
• Absorption:
• Rapidly absorbed, reaching Cpax in 1 to 2 h.
• Can be given orally, IM, IV, Inhalational and topical.
• Distribution:
• Plasma protein binding 70% to 90%.
Mechanism of Action:-
The corticosteroids bind to specific intracellular cytoplasmic receptors in target
tissues. Glucocorticoid receptors are widely distributed throughout the body. These receptors
are found in the brain also. After dimerizing, the receptor—hormone complex recruits coactivator
(or corepressor) proteins and translocates into the nucleus, where it attaches to gene
promoter elements. There it acts as a transcription factor to turn genes on or off,
depending on the tissue. This mechanism requires time to produce an ezect. However,
other glucocorticoid eXects are immediate, such as the
Mechansim of Action:-
The antiinflammatory actions of glucocorticoids are thought to involve phospholipase A2
inhibitory proteins, lipocortins, which control the biosynthesis of potent
mediators of inflammation such as prostaglandins and leukotrienes. Prednisolone reduces
inflammatory reaction by limiting
Therapeutic Uses:-
Relief of inflammatory symptoms: Corticosteroids significantly reduce the manifestations of
inflammation associated with rheumatoid arthritis and inflammatory skin conditions, including
redness, swelling, heat, and tenderness that may be present at the site of inflammation.
These agents are also important for maintenance of symptom control in persistent
asthma, as well as management of asthma exacerbations and active
Therapeutic Uses:-
• dermatologic diseases;
• endocrine conditions;
• GI diseases;
• hematologic diseases;
• neoplastic conditions; neoplastic diseases;
• nervous system conditions (eg, acute exacerbations of multiple
ADRs:-
• Decreased growth in children
• Glaucoma
• Centripetal distribution of body
• Increased appetite
• Emotional disturbances
• Hypokalemia
• Hypertension
• Peripheral edema
Discontinuation:-
Sudden discontinuation of these drugs can be a serious problem if the patient has
suppression of the HPA axis. In this case, abrupt removal of corticosteroids causes acute
adrenal insuXiciency that can be fatal. This risk, coupled with the possibility that
withdrawal might cause an exacerbation of the disease, means that the dose must be tapered
slowly according to individual tolerance. The patient must be monitored carefully.