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Note that kp = k12, kd = k21. (D) Two compartment model defined in terms of the drug amount, where Nbl is the amount of drug in blood (mg), and Np is the amount in peripheral tissue (mg). (E) Three compartment model with the addition of a tumor “compartment” where Nt is the amount of drug in the tumor.
The drugs are classified in BCS on the basis of solubility and permeability. Solubility class boundaries are based on the highest dose strength of an immediate release product. A drug is considered highly soluble when the highest dose strength is soluble in 250 ml or less of aqueous media over the pH range of 1 to 6.8.
Multiphasic absorption: Drugs injected intravenously are removed from the plasma through two primary mechanisms: (1) Distribution to body tissues and (2) metabolism + excretion of the drugs. The resulting decrease of the drug's plasma concentration follows a biphasic pattern (see figure). Plasma drug concentration vs time after an IV dose
Equation 1: = / / The drug apparent permeability (P app) is calculated by normalizing the drug flux (j) over the initial concentration of the API in the donor compartment (c 0) as: Equation 2: = / Dimensionally, the P app represents a velocity, and it is normally expressed in cm/sec. The highest is the permeability, the highest is expected to ...
Absorption is the journey of a drug travelling from the site of administration to the site of action. [ 1 ] [ 2 ] The drug travels by some route of administration ( oral , topical-dermal , etc.) in a chosen dosage form (e.g., tablets , capsules , or in solution ). [ 3 ]
At the beginning of the test, the drug is added to the donor compartment, and the acceptor compartment is drug-free. After an incubation period which may include stirring, the sandwich is separated and the amount of drug is measured in each compartment. Mass balance allows calculation of drug that remains in the membrane.
Distribution in pharmacology is a branch of pharmacokinetics which describes the reversible transfer of a drug from one location to another within the body.. Once a drug enters into systemic circulation by absorption or direct administration, it must be distributed into interstitial and intracellular fluids.
Pulmonary drug delivery is mainly utilized for topical applications in the lungs, such as the use of inhaled beta-agonists, corticosteroids and anticholinergic agents for the treatment of asthma and COPD, the use of inhaled mucolytics and antibiotics for the treatment of cystic fibrosis (CT) and respiratory viral infections, [1] and the use of inhaled prostacyclin analogs for the treatment of ...