What effect does caffeine have on the respiratory center of the medulla oblongata?

Caffeine exerts an analeptic effect by stimulating depressed vital centers of the central nervous system. The substance directly excites the respiratory center in the medulla oblongata, reducing the depressant effects of hypnotics and general anesthetics. Furthermore, the drug exhibits a moderate excitatory effect on all parts of the central nervous system.

How does caffeine affect diuresis and glomerular filtration?

Caffeine increases urine output and dilates renal blood vessels. Its effect on glomerular filtration is not specified in the referenced sources.

Why does caffeine increase blood pressure?

The drug exerts a direct stimulating effect on the vasomotor center, leading to increased vascular tone.

How does caffeine interact with PDE?

Caffeine inhibits the enzyme phosphodiesterase, preventing the breakdown of cAMP and promoting its accumulation in cells.

Does urine pH affect caffeine elimination?

Yes, because caffeine is a weak base; in acidic urine, it is ionized more actively and excreted faster, shortening its duration of action.

Home › Pharmacology › Caffeine-Sodium Benzoate

Caffeine-Sodium Benzoate

*Coffeinum-natrii benzoas*

For medical students2 min readUpdated 2026-10-10

Caffeine-sodium benzoate is a psychostimulant from the methylxanthine derivative group. The drug exerts a pronounced stimulating effect on the central nervous system, enhancing mental and physical performance.

Pharmacological groupPsychostimulants, methylxanthine derivatives.

FormulationsTablets 0.1–0.2 g; 10% and 20% solutions in 1 and 2 mL ampoules.

Mechanism of actionAdenosine receptor blockade and phosphodiesterase inhibition.

Dosing regimenOrally 0.1–0.2 g 2–3 times a day; subcutaneously (max single dose 0.4 g, max daily dose 1.0 g).

Mechanism of Action

The molecular effects of the drug are mediated through three primary pathways:

Adenosine receptor blockade: caffeine is a competitive antagonist of adenosine. By eliminating its inhibitory influence (cellular hyperpolarization), the drug activates CNS neurons.
Phosphodiesterase (PDE) inhibition: slowing the degradation of cAMP leads to its accumulation in brain and myocardial tissues, which enhances metabolic processes.
Effects on intracellular calcium: modulation of $Ca^{2+}$ ion levels within cells.

Pharmacological Effects

The drug stimulates mental and physical activity, eliminating drowsiness and fatigue. Its hemodynamic effects involve stimulation of the vasomotor center: in hypotension, caffeine raises blood pressure, whereas at normal blood pressure, it has virtually no effect. Additionally, caffeine potentiates the action of non-narcotic analgesics, making it a common component in combination medications (e.g., Citramon).

Indications for Use

Caffeine-sodium benzoate is prescribed for conditions accompanied by CNS depression, drowsiness, and hypotensive states. In combination therapy, it is used for migraines (combined with ergot alkaloids) and as a component of analgesic formulations.

Side Effects and Contraindications

Main side effects include psychomotor agitation, insomnia, tachycardia, arrhythmias, and dyspeptic symptoms (nausea, vomiting). Long-term use may lead to dependence (theism).

Contraindications: severe arterial hypertension, atherosclerosis, glaucoma, and insomnia.

Pharmacokinetics and Administration Notes

Caffeine is a substrate for the CYP1A2 isoenzyme. Its metabolism depends on diet and environmental factors (e.g., smoking induces this enzyme, accelerating caffeine clearance). The drug is excreted in breast milk. It is important to consider that caffeine is a weak base; therefore, urinary acidification accelerates its excretion and diminishes its pharmacological action.

Mnemonic

Caffeine is an "adenosine blocker": it prevents adenosine from "braking" the brain, keeping us alert.

Frequently asked questions

What effect does caffeine have on the respiratory center of the medulla oblongata?: Caffeine exerts an analeptic effect by stimulating depressed vital centers of the central nervous system. The substance directly excites the respiratory center in the medulla oblongata, reducing the depressant effects of hypnotics and general anesthetics. Furthermore, the drug exhibits a moderate excitatory effect on all parts of the central nervous system.
How does caffeine affect diuresis and glomerular filtration?: Caffeine increases urine output and dilates renal blood vessels. Its effect on glomerular filtration is not specified in the referenced sources.
Why does caffeine increase blood pressure?: The drug exerts a direct stimulating effect on the vasomotor center, leading to increased vascular tone.
How does caffeine interact with PDE?: Caffeine inhibits the enzyme phosphodiesterase, preventing the breakdown of cAMP and promoting its accumulation in cells.
Does urine pH affect caffeine elimination?: Yes, because caffeine is a weak base; in acidic urine, it is ionized more actively and excreted faster, shortening its duration of action.

Go deeper

Caffeine interaction with other CYP1A2 substrates (theophylline, warfarin).
Clinical significance of hepatic microsomal enzyme induction and inhibition.
Comparative profile of methylxanthine derivatives (theobromine, theophylline).
Mechanisms of drug dependence development (theism).
Principles of forced diuresis in intoxications.