Pharmaceutics & Dosage Forms

Dissolution

TRÇözünme (Dissolüsyon)
Also known as:Drug dissolution

The process by which a solid drug passes into solution in a solvent such as gastrointestinal fluid; for solid oral dosage forms it is a prerequisite for absorption and often its rate-limiting step.

Formula

dM/dt = D × A × (Cs − C) / h

In depth

Dissolution rate is described by the Noyes–Whitney equation, in which dM/dt is the rate of dissolution, D the diffusion coefficient, A the surface area, Cs the saturation solubility, C the concentration in the bulk medium and h the diffusion-layer thickness. Particle-size reduction, amorphous or salt forms, solid dispersions and surfactants are used to speed dissolution of poorly soluble drugs.

Dissolution testing with pharmacopoeial apparatus (basket, paddle) under defined pH and agitation is a key quality-control test, is used to compare generic and reference products and supports BCS-based biowaivers when both products dissolve rapidly and similarly.

Clinical pearl

Dissolution-limited absorption explains why some poorly soluble drugs, such as itraconazole capsules, are better absorbed with food or in an acidic stomach and poorly absorbed with acid-suppressing drugs.

Example drugs

Itraconazole
TRIn Turkish

Çözünme (Dissolüsyon)

Katı bir ilacın gastrointestinal sıvı gibi bir çözücü içinde çözeltiye geçme sürecidir; katı oral dozaj şekillerinde absorpsiyonun ön koşulu ve çoğu zaman hız sınırlayıcı basamağıdır.

Çözünme hızı Noyes–Whitney denklemiyle tanımlanır; burada dM/dt çözünme hızı, D difüzyon katsayısı, A yüzey alanı, Cs doygunluk çözünürlüğü, C ortamdaki konsantrasyon, h ise difüzyon tabakası kalınlığıdır. Az çözünen ilaçlarda çözünmeyi hızlandırmak için partikül boyutunun küçültülmesi, amorf veya tuz formları, katı dispersiyonlar ve yüzey etkin maddeler kullanılır.

Farmakope aparatlarıyla (sepet, palet) tanımlı pH ve karıştırma koşullarında yapılan çözünme testi temel bir kalite kontrol testidir; jenerik ve referans ürünlerin karşılaştırılmasında kullanılır ve her iki ürün hızlı ve benzer biçimde çözündüğünde BCS temelli biyomuafiyeti destekler.

Çözünmeyle sınırlı absorpsiyon, itrakonazol kapsül gibi az çözünen bazı ilaçların yemekle veya asidik mide ortamında daha iyi, asit baskılayıcı ilaçlarla ise yetersiz absorbe edilmesini açıklar.

Diğer adları:Dissolüsyon
Updated 24.09.2026 0 views Educational reference — verify against current sources before clinical use.

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SolubilityÇözünürlük

The maximum amount of a substance that dissolves in a given volume of solvent at equilibrium under specified conditions of temperature, pH and medium composition.

 Biopharmaceutics Classification SystemBiyofarmasötik Sınıflandırma Sistemi

A scientific framework that classifies drug substances into four classes according to their aqueous solubility and intestinal permeability, the two main determinants of the rate and extent of oral absorption.

 BioequivalenceBiyoeşdeğerlik

The absence of a significant difference in the rate and extent of absorption of the active substance when two pharmaceutically equivalent or alternative products are given at the same molar dose under similar conditions.

 Immediate-Release FormulationHemen Salımlı Formülasyon

A dosage form designed to release the active substance promptly after administration, without deliberate modification of the release rate, so that absorption is governed mainly by dissolution and gastrointestinal physiology.

 AbsorptionAbsorpsiyon

The process by which a drug enters the bloodstream from the site of administration, such as the gastrointestinal tract, skin, or lungs.

 Salt FormTuz Formu

A form of an ionisable drug substance combined with a pharmaceutically acceptable counterion, such as hydrochloride, sodium, maleate or mesilate, chosen to improve solubility, stability, crystallinity or manufacturability.