Pharmacokinetics and Routes of Administration
The pharmacological properties of the drug directly depend on its route of administration:
- Sublingual (under the tongue): Provides a rapid onset of action within 2–5 minutes. It has a relatively high bioavailability (about 60%), and the effect lasts for 1–2 hours (or 15 minutes to 2 hours when tablets are chewed).
- Oral (by mouth): Acts more slowly (onset in 15–40 minutes). Due to significant first-pass hepatic metabolism, bioavailability drops to 20%. Standard tablets work for 4–6 hours, while extended-release (retard) formulations provide an effect for 8–12 hours.
Oral administration yields an important active metabolite, isosorbide-5-mononitrate, which has a half-life of 2–4 hours.
Clinical Application
In medical practice, the drug is prescribed in the following clinical scenarios:
- Angina pectoris: Sublingual forms are used for the acute relief of attacks, while oral formulations are used for routine prophylaxis.
- Chronic heart failure: Used as an effective vasodilator. It serves as an alternative therapeutic option when ACE inhibitor therapy is not feasible.
Side Effects and Dosage Forms
The adverse effect profile is similar to that of nitroglycerin, although it is generally better tolerated by patients with milder side effects.
In addition to standard sublingual and oral tablets, alternative dosage forms include:
- Solutions intended for intravenous administration;
- Special transdermal systems (e.g., transdermal patches) for cutaneous use.