Classification and pharmacokinetics
Nitrong tablets belong to the group of microencapsulated tablet formulations. Other representatives of this category include Nitrogranulong and Sustac Forte.
Since the formulation is intended for swallowing (absorption occurs via the gastrointestinal tract), the drug has specific timeframes of action:
- Latent period (the time from administration to the onset of action) is 10–20 minutes.
- Duration of effect persists for approximately 6 hours, making it convenient for maintaining a prolonged therapeutic result.
Dosage features and metabolism
Students need to understand why the dosage of nitroglycerin in Nitrong tablets differs significantly from sublingual forms.
The drug contains significantly higher doses (greater than 0.005 g). This is not accidental, but a pharmacokinetic necessity. Upon absorption from the gastrointestinal tract, the active substance enters the liver first via the bloodstream. There, it undergoes intensive degradation (first-pass effect). For a sufficient number of molecules to reach the systemic circulation to produce a therapeutic effect, the initial dose in the microencapsulated tablet must be high.
Alternatives: transdermal forms
To bypass hepatic degradation and avoid gastrointestinal absorption, transdermal (topical) formulations are used in pharmacology. In this case, absorption occurs directly through the skin.
There are two main topical formulations:
- Nitroglycerin ointment (2%) — starts acting in 30–40 minutes, with a total duration of effect reaching up to 5 hours.
- Transdermal therapeutic systems (TTS or patches) — these include Nitropercuten TTS and Deponit.
Patches are applied to healthy skin for 10–12 hours. Their mechanism is based on the uniform release of the substance (at a dose of 0.0005 g per 1 cm² per 24 hours). The effect of TTS develops on average within 30 minutes, and the total duration of action directly depends on how long the patch remains on the skin.
Briefly: answers to topical questions
What are the pharmacokinetic features of Nitrong tablets?
The pharmacokinetic features of Nitrong tablets include a delayed onset and prolonged maintenance of the therapeutic effect.
- Onset of action — the latent period is 10–20 minutes.
- Duration of effect — persists for about 6 hours.
- Metabolism — upon absorption from the gastrointestinal tract, the drug undergoes intensive degradation in the liver, which is why the tablets contain high doses of nitroglycerin (more than 0.005 g).
What are the main indications for Nitrong tablets?
The primary use of prolonged-release nitrate tablet formulations is the prevention of angina attacks.
- Prevention of attacks — sources indicate that prolonged-release nitrate formulations, including tablets, are used for prevention.
- Nitrong tablets belong to microencapsulated tablet formulations of nitroglycerin; the onset of action is 10–20 minutes, and the duration of effect is about 6 hours.
What side effects may occur when taking Nitrong tablets?
Side effects when taking Nitrong tablets may occur due to the systemic vasodilating action of nitroglycerin.
- Central nervous system — severe headache and dizziness.
- Cardiovascular system — hypotension (up to orthostatic collapse), reflex tachycardia, facial flushing, and a feeling of warmth.
- Blood system — methemoglobinemia is possible in case of overdose.
Because the drug is a prolonged-release formulation, there is a high risk of developing tolerance with its use, and withdrawal syndrome upon abrupt cessation.
What is the mechanism of the antianginal action of nitroglycerin?
The mechanism of the antianginal action of nitroglycerin is based on systemic vasodilation, which reduces myocardial oxygen demand.
- Molecular level — enzymatic release of nitric oxide (NO) involving thiol enzymes, leading to cGMP accumulation and vascular relaxation.
- Reduction of preload — venous dilation decreases venous return to the heart.
- Reduction of afterload — arterial dilation decreases peripheral vascular resistance.
- Coronary blood flow — redistribution of blood flow occurs in favor of ischemic subendocardial layers.
The word "Nitrong" can be broken down as "NITROglycerin + lONG". These are microcapsules that work for a long time — about 6 hours.
Class and exam questions
Why is the active substance dose in Nitrong tablets greater than 0.005 g?
The high dose is necessary to compensate for the intensive degradation of the drug in the liver. Upon absorption from the gastrointestinal tract, the substance inevitably passes through the hepatic barrier, where it loses part of its activity.
How soon will the patient feel the effect after administration?
The latent (hidden) period for microencapsulated tablets ranges from 10 to 20 minutes.
Which drugs belong to the same group as Nitrong?
Microencapsulated tablet formulations also include Nitrogranulong and Sustac Forte.
What is the main difference between transdermal forms and Nitrong tablets?
Transdermal forms (ointments and patches) are absorbed through the skin, completely bypassing the gastrointestinal tract and first-pass hepatic metabolism.
What else to study on this topic
- Comparative characteristics of Nitrogranulong, Nitrong, and Sustac Forte
- Mechanism of uniform release in TTS (Nitropercuten TTS, Deponit)
- Pharmacokinetics of 2% nitroglycerin ointment
- Advantages of transdermal absorption over gastrointestinal absorption
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