guanabenz

Action and Spectrum

Actions and Spectrum: 

• guanabenz’s primary target is the alpha-2 adrenergic receptors in the brain’s vasomotor center. Activation of these receptors inhibits the release of norepinephrine, a neurotransmitter involved in regulating blood pressure. By reducing sympathetic activity, guanabenz decreases peripheral vascular resistance, leading to a reduction in blood pressure. 
• In addition to its antihypertensive effects, guanabenz exhibits sedative properties due to its action on alpha-2 adrenergic receptors in the central nervous system.  
• Regarding the spectrum of activity, guanabenz primarily acts on the alpha-2 adrenergic receptors in the central nervous system. Its effects are, therefore, mainly seen in regulating blood pressure and sympathetic outflow from the brain. 

Drug Interaction

Adverse Reaction

Frequency not defined 

Dry mouth 

Sedation/drowsiness 

Dizziness 

Black Box Warning

Black box warning: 

None 

Contraindication / Caution

Contraindications/caution: 

Contraindications: 

Hypersensitivity 

Caution: 

Hypotension 

Sedation 

Abrupt discontinuation 

Pregnancy / Lactation

Pregnancy consideration: Insufficient data available 

Lactation: Excretion of the drug in human breast milk is unknown 

Pregnancy category: 

Category A: well-controlled and Satisfactory studies show no risk to the fetus in the first or later trimester. 

Category B: there was no evidence of risk to the fetus in animal studies, and there were not enough studies on pregnant women. 

Category C: there was evidence of risk of adverse effects in animal reproduction studies, and no adequate evidence in human studies must take care of potential risks in pregnant women.    

Category D: adequate data with sufficient evidence of human fetal risk from various platforms, but despite the potential risk, and used only in emergency cases for potential benefits.    

Category X: Drugs listed in this category outweigh the risks over benefits. Hence these categories of drugs need to be avoided by pregnant women.    

Category N: There is no data available for the drug under this category 

Pharmacology

Pharmacology: 

It involves selective activation of alpha-2 adrenergic receptors in the central nervous system, reducing sympathetic outflow, peripheral vasodilation, and decreased blood pressure. 

Pharmacodynamics: 

As a centrally acting alpha-2 adrenergic agonist, it exerts its antihypertensive effects by targeting alpha-2 adrenergic receptors in the central nervous system. By stimulating these receptors, guanabenz inhibits sympathetic outflow from the brain, leading to vasodilation, reduced peripheral vascular resistance, and ultimately a decrease in blood pressure 

Pharmacokinetics: 

Absorption 

Its bioavailability is approximately 70%. The time to reach peak plasma concentration (Tmax) is typically within 1 to 4 hours after oral dosing. 

Distribution 

guanabenz is extensively distributed throughout the body. It has a moderate volume of distribution, indicating that it distributes well into tissues. The drug readily crosses the blood-brain barrier, allowing it to exert its effects on central alpha-2 adrenergic receptors. 

Metabolism 

guanabenz undergoes extensive metabolism in the liver. The primary metabolic pathway is glucuronidation, which is conjugated with glucuronic acid to form inactive metabolites. The main metabolite formed is guanabenz glucuronide.  

Elimination and Excretion 

The elimination of guanabenz and its metabolites occurs primarily through renal excretion. Approximately 60% to 70% of the administered dose is excreted in the urine, primarily as the glucuronide metabolite. The remaining portion is excreted in feces. The elimination half-life of guanabenz is approximately 5 to 7 hours, indicating that it is eliminated relatively quickly from the body. 

Adminstartion

Administration: 

The dosage is typically initiated at a low dose and gradually increased as needed to achieve the desired blood pressure control. guanabenz tablets should be swallowed whole with a glass of water. 

Patient Information Leaflet

Patient information leaflet 

Generic Name: guanabenz 

Why do we use guanabenz? 

guanabenz is primarily used to treat hypertension (high blood pressure). It is classified as a centrally acting alpha-2 adrenergic agonist and exerts its antihypertensive effects by acting on alpha-2 adrenergic receptors in the central nervous system. Here are the primary uses of guanabenz: 

• Hypertension: guanabenz is indicated for the management of hypertension. guanabenz helps lower blood pressure by reducing sympathetic outflow from the brain, leading to vasodilation and decreased peripheral vascular resistance.