Chapter 15 Adrenergic agonists and antagonists Flashcards
Adrenergic agonists
Drugs that stimulate the sympathetic nervous system because they mimic the sympathetic neurotransmitters norepinephrine and epinephrine. Act on Adrenergic receptors
Adrenergic receptor
Sites locates in the effector cells of muscles such as the heart, bronchiole walls, GI tract, urinary bladder, and ciliary muscles of the eye. Alpha and beta 1-2 receptors
Alpha 1
Increases for of heart contraction vasoconstriction increases BP, mydriasis (dilation of pupils), secretion in salivary glands decreases, urinary bladder relaxation and urinary sphincter contraction increases
Alpha 2
Inhibits release of norepinephrine, dilates blood vessels, produces hypotension, decreases GI motility and tone
Beta 1
Increases HR and force of contraction, increases renin secretion, increasing BP
Beta 2
Dilates bronchioles, promotes GI and uterine relaxation; promotes increases in blood glucose through glycogenolysis in the liver, increases blood flow in skeletal muscles
Sympathetic affects
Eye (dilate), lung. (Dilate bronchioles), heart 9increased HR), blood vessel (constrict), gastrointestinal(decrease motility), bladder (relax), uterus (relax)
Inactivation of neurotransmitters
Inactivated by regulate of the transmitter back into the neuron. Transformation or degradation, diffusion away from the receptor .
Sympathomimetics
Adrenergic agonist. Drugs that stimulate adrenergic receptors are classified into 3 categories according to their effects on organ cells.
Direct acting sympathomimetics
Direc5tky stimulate the adrenergic receptor (epi or norepinephrine
Indirect acting symp
Which stimulate the release of norepinephrine from the terminal of the nerve endings
Mixed-acting sympathomimetics
Which stimulate the adrenergic receptor sites and stimulate the release of epi and norepinephrine
(Pseudoephedrine)
Catecholamines
Chemical structures of a substance either endogenous or synthetic that can induce a sympathomimetic response
Noncatecholamines
Have a longer duration of action. Stimulate more than one adrenergic receptor
Epinephrine pharmacokinetics
Can be administered subq, IV, topically, inhalation, or intracardiac. Not given orally because It is rapidly metabolized in the GI tract and liver. Metabolized by the liver.
Epinephrine pharcadynamics
Used in emergency to treat anaphylaxis. (Allergic response). Myocardial contraction strengthening drug that increases cardiac output, promotes constriction, and systolic BP increase, increase HR and produces bronchodilation.
Albuterol pharmacokinetics
Well absorbed by Gi tract and metabolized by liver. Half-life= 2.7-6 hours
Albuterol pharmacodynamics
Prevent and treat bronchospasm. With inhalation, the onset of action of albuterol is 5-15 minutes by inhalation
Albuterol
Beta2 adrenergic agonist, is selective for beta2 adrenergic receptors, so the response is relaxation of bronchial smooth muscle and bronchodilation.
Adrenergic agonists drugs
Epinephrine (A, A2, B, B2) Ephedrine (A, B, B2) Norepinephrine (A, B) Dopamine (A, B) Midodrine (a) Phenylephrine HCl (A, A2, B) Albuterol (b2) Metaproterenol sulfate (b2) Dobutamine HCl (b) Terbutaline sulfate (b2)
Alpha 2 drugs
Act by decreasing the release of norepinephrine from sympathetic nerves
Adrenergic antagonists
Block the effects of adrenergic neurotransmitters.
Alpha adrenergic antagonists
Drugs that block or inhibit a response at the alpha adrenergic receptor. Selective and non selective blockers
Alpha 1 blocker
Vasodilation; decreases BP; reflex tachycardia might result, mydriasis occurs, suppresses evaluation, reduces contraction of smooth muscles in bladder neck and prostate gland
Beta 1 blockers
Decreases HR; reduces force of contractions
Beta 2 blockers
Constricts bronchioles, contracts uterus, inhibits glycogenolysis, which can decrease blood glucose
