Pharmacokinetic features in systemic use
As a pronounced lipophilic compound, Betaxololum is almost completely absorbed in the gastrointestinal tract. It is important to note that concomitant food intake does not alter its absorption parameters, making the therapy regimen more convenient for the patient.
A key pharmacokinetic feature of the drug is the absence of the "first-pass" effect through the liver. Due to this, its bioavailability reaches high values of 80–90%. Elimination occurs primarily via hepatic metabolism (about 85% of the substance is converted into inactive metabolites), after which these metabolites are excreted by the kidneys.
The drug belongs to long-acting agents: the clinical effect lasts up to 36 hours, and the half-life ($t_{1/2}$) ranges from 14 to 22 hours. However, if the patient has concomitant hepatic or renal impairment, this period predictably lengthens, which necessitates mandatory adjustment of the therapeutic dose.
Use in cardiology
Systemic administration of betaxolol (orally) is indicated for a number of cardiovascular pathologies. In clinical practice, it is used to treat:
- Arterial hypertension (to achieve stable control of blood pressure levels);
- Exertional angina;
- Tachyarrhythmias.
Due to its long half-life, the drug is prescribed in a convenient regimen—only once a day, which improves patient adherence to treatment.
Betaxolol in ophthalmology
In addition to cardiology, the drug has found widespread use in the treatment of eye diseases. For these purposes, a special dosage form is produced—eye drops (known under the trade name «Betoptic»).
The main indication for topical use is open-angle glaucoma. Instillation of the solution into the conjunctival sac leads to an effective decrease in intraocular pressure. The pharmacodynamic effect after a single instillation lasts for 12 hours.
Adverse reactions and risks
When using eye drops, a number of side effects may develop, which are generally divided into local and systemic.
Local reactions include:
- Burning sensation and eye pain;
- Itching and conjunctival hyperemia;
- Development of allergic conjunctivitis.
Resorptive (systemic) effects occur if the drug is absorbed from the mucous membrane of the eye into the systemic circulation. In this case, the classic effects of beta-blockers may be observed: bradycardia and arterial hypotension.
Special attention should be paid to patients with a burdened allergic and pulmonary history: in the presence of bronchial asthma, the resorptive effect of betaxolol carries a high risk of developing life-threatening bronchospasm.
Briefly: answers to topical questions
What pharmacological group does betaxolol belong to?
Betaxolol belongs to the pharmacological group of cardioselective $\beta_1$-blockers. In the classification by generations, it is included in the 2nd generation of drugs.
- Cardioselective — selective blockers of $\beta_1$-receptors.
Additionally, the drug is characterized as lipophilic, possesses weak membrane-stabilizing activity, and belongs to long-acting agents. The cardioselectivity index is 25/1.
What is the mechanism of intraocular pressure reduction when using betaxolol?
The mechanism of intraocular pressure reduction with betaxolol involves a decrease in the production of intraocular fluid. This effect is achieved through the drug's action on the ciliary epithelium, which leads to reduced fluid secretion. This property allows the drug to be used as eye drops for the treatment of open-angle glaucoma.
How does betaxolol differ from non-selective beta-blockers in ophthalmology?
Betaxolol in ophthalmology differs in that it is a cardioselective $\beta_1$-blocker and is indicated among the drugs of choice for glaucoma. Non-selective propranolol blocks $\beta_1$- and $\beta_2$-receptors and is not used in glaucoma because it has pronounced local anesthetic activity and is associated with the risk of corneal damage.
| Characteristic | Betaxolol | Propranolol |
|---|---|---|
| Selectivity | Cardioselective $\beta_1$-blocker | Non-selective $\beta_1, \beta_2$-blocker |
| Use in glaucoma | Drug of choice | Not used |
| Reason for restriction | Not specified in sources | Pronounced local anesthetic activity, risk of corneal damage |
The rule of two "P"s will help remember pharmacokinetics: Complete absorption, Almost 100% bioavailability (no First Pass effect).
Class and exam questions
Does food intake affect the absorption of betaxolol?
No, the lipophilic structure of the drug allows it to be almost completely absorbed in the gastrointestinal tract regardless of food intake.
How often should betaxolol tablets be taken?
Due to its prolonged action (effect up to 36 hours), the drug is taken orally once a day.
Why can blood pressure drop when using eye drops?
This is due to the resorptive effect: when the drug is absorbed from the conjunctival sac into the blood, its systemic action manifests (hypotension, bradycardia).
What else to study on this topic
- Mechanism of intraocular pressure reduction in open-angle glaucoma
- Principles of dose adjustment in renal and hepatic impairment
- Pathogenesis of bronchospasm development under the resorptive action of eye drops
- Differences between betaxolol and other drugs used for tachyarrhythmias
Master the entire topic in the «Pharmacology» course
This is a summary. The course covers everything tested in classes and exams.
- Complete study guide on "Betaxolol" and another 5,304 pages of the subject
- Assignments and quizzes after every topic — just like in a colloquium
- AI tutor answers questions on the topic anytime
- 116 video lessons on the subject
Other topics in the section "Drugs Acting on Adrenergic Synapses"
Free video lessons: pharmacologyShort lessons with study notes — no registration required.
Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.