Cocaine is the Only Vasoconstrictor Among the Listed Options
Among the options provided - procaine, bupivacaine, lidocaine, and cocaine - only cocaine is a vasoconstrictor. 1
Mechanism of Action of Cocaine as a Vasoconstrictor
- Cocaine blocks the reuptake of norepinephrine and dopamine at presynaptic adrenergic terminals, causing an accumulation of catecholamines at postsynaptic receptors, acting as a powerful sympathomimetic agent 1
- Even small doses of cocaine taken intranasally have been associated with vasoconstriction of coronary arteries 1
- Vasoconstriction with cocaine use is primarily due to stimulation of α-adrenergic receptors in smooth muscle cells in coronary arteries 1
- Cocaine also increases levels of endothelin-1 (a powerful vasoconstrictor) and decreases production of nitric oxide (a vasodilator) 1
Characteristics of the Other Local Anesthetics
- Procaine, bupivacaine, and lidocaine are all amide or ester local anesthetics that do not possess significant vasoconstrictive properties 2
- In fact, most local anesthetics (including procaine, bupivacaine, and lidocaine) actually cause mild vasodilation rather than vasoconstriction 2
- Due to this vasodilatory effect, epinephrine is often added to local anesthetic formulations to provide vasoconstriction and prolong the anesthetic effect 3
Clinical Implications of Cocaine's Vasoconstrictive Properties
- Cocaine's vasoconstrictive effects contribute to its cardiovascular toxicity, including hypertension, myocardial ischemia, and myocardial infarction 1
- In clinical settings where vasoconstriction is desired (such as nasal procedures), cocaine has historically been used as both an anesthetic and vasoconstrictor 4
- However, safer alternatives to cocaine for achieving vasoconstriction in clinical settings are now available, such as combinations of lidocaine with oxymetazoline 5
Important Cardiovascular Effects of Cocaine
- Cocaine causes increased heart rate and blood pressure in a dose-dependent fashion 1
- In humans, intranasal cocaine use results in increases in heart rate, mean systemic arterial pressure, cardiac index, and contractility 1
- The combination of cocaine and cigarette use results in greater increases in heart rate and vasoconstriction than either cocaine use or cigarette smoking alone 1
- Cocaine users can develop ischemic chest discomfort due to these vasoconstrictive effects 1
Treatment Considerations for Cocaine-Induced Vasoconstriction
- Calcium channel blockers can reverse cocaine-induced increases in coronary vascular resistance 1
- Beta blockers alone should be avoided in patients with acute cocaine intoxication due to the risk of potentiating coronary spasm through unopposed alpha-adrenergic stimulation 1
- Benzodiazepines alone or in combination with nitroglycerin are reasonable for management of hypertension and tachycardia in patients with signs of acute cocaine intoxication 1
In summary, among the options presented, only cocaine acts as a vasoconstrictor through its sympathomimetic effects, while procaine, bupivacaine, and lidocaine do not possess significant vasoconstrictive properties.