pharmacology of vasoconstrictors Flashcards
(57 cards)
What are vasoconstrictors?
Substances that cause contraction of smooth muscle in the vasculature, increasing vascular tone.
How do vasoconstrictors affect arteries and arterioles?
They cause contraction, increasing blood pressure by raising vascular resistance.
How do vasoconstrictors affect venules and veins?
They cause contraction, increasing blood pressure by decreasing the space available for blood storage.
What is one use of vasoconstrictors in dentistry related to local anesthesia?
They are co-formulated with local anesthetics (LAs) to provide local anesthesia.
How are vasoconstrictors used in oral surgery?
They help control bleeding (hemostatic effect)
How do vasoconstrictors assist in emergency situations?
They are used to treat acute anaphylaxis.
What is the action of vasoconstrictors with local anesthetics?
They act as agonists at α1 adrenergic receptors.
What is the effect of vasoconstrictors on vascular smooth muscle?
They cause contraction of vascular arteriolar smooth muscle.
What is the response of vasoconstrictors on blood flow at the site of local anesthetic injection?
They reduce blood flow to the site of injection.
How do vasoconstrictors affect the absorption of local anesthetics?
They slow the rate of absorption into systemic circulation, limiting side effects.
How do vasoconstrictors enhance the effectiveness of local anesthetics?
They prolong the duration of the anesthetic at the injection site.
What are the two vasoconstrictors co-formulated with local anesthetics?
Epinephrine
Levonordefrin (only combined with mepivacaine)
How do epinephrine and levonordefrin differ in potency and concentration?
Levonordefrin is less potent than epinephrine.
Higher concentrations of levonordefrin (e.g., 1:20,000) are used compared to epinephrine (e.g., 1:50,000 or 1:100,000) to achieve a similar effect.
What is a common side effect of local anesthetics, and how does it affect their duration?
vasodilating activity, which enhances their absorption into the blood.
This results in a shorter duration of anesthesia if used without a vasoconstrictor.
What is Epinephrine (Epi)?
Structural Class: Catecholamine.
Source: Endogenous hormone released from the adrenal medulla (inner part of the adrenal gland) in response to sympathetic nervous system (SNS) activation.
What happens when the SNS is activated (e.g., fight or flight response)?
Epinephrine is released into the blood, enhancing:
Cardiac output.
Blood flow to muscles.
What does “catecholamine” mean?
Catechol: two OH groups on adjacent carbons of a ring.
Amine: Refers to a nitrogen-containing group.
What are the key effects of a short-term stress response?
Heart rate increases
Metabolic rate increases
Blood pressure increases
Bronchioles dilate
Liver converts glycogen to glucose and releases glucose to the blood
Blood flow changes, reducing digestive system activity and urine output
What are the key effects of a long-term stress response?
Kidneys retain sodium and water
Blood volume, blood pressure blood glucose increases
Proteins and fats are converted to glucose or broken down for energy
Immune system is suppressed
What are the receptors for catecholamines called?
Adrenergic receptors.
Why are they called adrenergic receptors?
They are the receptors for adrenaline (epinephrine).
What is norepinephrine (NE)?
A catecholamine similar in activity to epinephrine.
Released by neurons instead of the adrenal medulla.
How does epinephrine affect the heart?
Sinoatrial node and Ectopic pacemakers: Accelerates via β1, β2
Contractility: increases via β1, β
How does epinephrine affect blood vessels?
Skin, Mucosa, Splanchnic Vessels: Causes contraction via α receptors.
Skeletal Muscle Vessels: Relaxes via β2 receptors, Contracts via α receptors.
