With extended-release medications, the active ingredient is released slowly, stabilizing the drug concentration in the body, so patients do not have to take the medication multiple times (which can lead to forgetfulness). However, if used improperly, this formulation can also cause many dangers.
In extended-release medications, after the brand name, you often see additional letters: LP (libération prolongée = prolonged release), LA (long acting), SR (sustained release), retard release (slow release), slow release (slow release), timed release (time-released), delayed (delayed)…
To create an extended effect, a special formulation method is required:
Tablet form: This often uses dissolution or osmotic techniques. In the dissolution technique, the active ingredient is placed in polymer coatings of varying thickness or solubility. When it enters the body, the release of the active ingredient depends on this thickness or solubility. In the osmotic technique, the active ingredient and electrolytes are placed in a precisely perforated, uniform semipermeable membrane (made with laser). Upon entering the body, fluid passes through the semipermeable membrane, dissolving the active ingredients and electrolytes, creating osmotic pressure that pushes the active ingredient out through the perforations.
Lozenge form: This typically uses a technique that mixes the active ingredient with excipients that have a slow solubility. When held in the mouth, the active ingredient is released gradually.
Injection form: This usually involves a special solvent or a specific binding method with the solvent, injected into a specific location to reduce the elimination of the active ingredient, allowing it to remain in the body longer.
Benefits of Extended-Release Medications
Reduces the need for multiple doses during the day or treatment course: For instance, a hypertensive individual using Adalat retard (slow-release nifedipine) will take fewer doses than someone using Adalat (regular nifedipine). For patients with chronic conditions requiring medication for years or a lifetime, such as epilepsy (using Tergeton LP) or diabetes (using Glizipid LP), this formulation is much more convenient. In mountainous areas, depending on the level of iodine deficiency, a single injection of 0.2 ml-0.5 ml, up to 1 ml of Lipiodol, can prevent simple goiter for three years. This is particularly beneficial for those with chronic conditions who need to take multiple doses daily, often affecting the elderly who may forget to take their medications.
Concentrates the medication at a specific site for greater effect: In treatment, it is sometimes necessary for the active ingredient to be released gradually at a specific location. For example, the slow-dissolving Mycelex troches (containing clotrimazole) releases the active ingredient to treat Candida infections in the mouth and throat. The Mycelex-7 vaginal inserts (containing 100 mg of clotrimazole) only require one insert in the vagina at bedtime to treat vaginal Candida. Without using these slow-release lozenges or inserts, patients would need to take medications multiple times in higher doses.
Less risk of acute toxicity even with higher doses: Using Adalat 10 mg can sometimes cause sudden drops in blood pressure, but Adalat retard 20 mg is unlikely to have this side effect because the active ingredient is released gradually into the bodily fluids.
However, improper use can lead to ineffectiveness and sometimes cause harm:
Extended-release medications typically have a slow action; using them in emergency situations will not be effective. For example, if a patient has a high fever and needs immediate relief, they cannot use aspirin – pH8 (as it requires time to dissolve in the stomach and then gradually release in the intestines) but should use paracetamol instead. If needed, they can use rectal paracetamol for direct absorption into the bloodstream.
Within a specific timeframe, extended-release medications release an adequate amount of the active ingredient to treat the condition. If dosages are not calculated correctly or if they are not taken at the right time, it can be harmful. Between doses of Glizipid LP for diabetes, if additional medication or another glucose-lowering drug is taken, the continued release of the old medication combined with the new drug can lead to overdose and excessive glucose reduction.
More importantly, using these medications incorrectly can destroy the product’s structure, rendering it ineffective and sometimes toxic. With tablet forms, they must be swallowed whole, not broken or chewed. If broken or chewed, the polymer coating or semipermeable membrane will rupture, causing the active ingredient to be released all at once, leading to toxicity. For instance, the effective dose of Adalat is 10 mg. If Adalat retard 20 mg is broken or chewed, the active ingredient will release 20 mg all at once, double the necessary dose, causing a sudden drop in blood pressure.
A type of oil-soluble injectable medication is designed for subcutaneous injection; if injected deep into the muscle, the active ingredient will no longer be enveloped by the subcutaneous fat, releasing it faster and failing to achieve the desired extended effect.
DS Hữu Nam (Health & Life)
