Ointments are semi-solid topical preparations used to protect, soothe, or treat the skin or mucous membranes. They are typically composed of a greasy base that helps retain moisture and may contain active ingredients for various therapeutic purposes. Ointments are widely used in dermatology, wound care, and other medical applications. Preparation Methods Fusion Ingredients are melted … Read more
Several factors influence the rate and extent of drug penetration through the skin, which can be broadly classified into physiological factors, formulation factors, and physicochemical properties of the drug. 1. Physiological Factors Stratum Corneum Thickness: The stratum corneum is the primary barrier to drug penetration. Areas with thinner stratum corneum (e.g., the face, scalp) show … Read more
The skin has several layers, but drug penetration primarily occurs across the epidermis, particularly through the stratum corneum. There are three primary pathways for dermal penetration: 1. Transcellular (Trans-epidermal) Route Drugs pass directly through the keratinocytes (cells) of the stratum corneum. Challenges: This route requires the drug to partition into and out of the lipid-rich … Read more
Definition of Semisolid Dosage Forms Semisolid Dosage Forms are pharmaceutical preparations intended for external application to the skin or mucous membranes, having a consistency between solid and liquid. They are used for both local and systemic effects. These forms provide a medium for the drug to be delivered to the site of action, and their … Read more
Factors Causing Nonlinear Pharmacokinetics include enzyme saturation, protein binding, transport limits, and metabolic pathway shifts. Factors Causing Nonlinear Pharmacokinetics Nonlinear pharmacokinetics arises from the saturation of physiological processes involved in drug metabolism, absorption, distribution, or excretion. Key mechanisms include: Saturable Metabolism (Capacity-Limited Metabolism) Enzymes (e.g., CYP450, alcohol dehydrogenase) become saturated at high drug concentrations. Once … Read more
Michaelis Menten equation describes enzyme kinetics by relating reaction rate to substrate concentration in pharmacology. The Michaelis-Menten equation describes the kinetics of enzyme-catalyzed reactions, first proposed by Leonor Michaelis and Maud Menten in 1913. It expresses the relationship between reaction rate (V) and substrate concentration ([S]): $V = \frac{V_{\text{max}} \,[S]}{K_m + [S]}$ Where: V = … Read more
Michaelis-Menten Parameter Estimation Methods determine Km and Vmax values using graphical and computational approaches. Michaelis-Menten Parameter Estimation Methods Several methods estimate Vmax and Km from experimental data: Lineweaver-Burk Plot (Double Reciprocal Plot) By taking the reciprocal of the Michaelis-Menten equation: $\frac{1}{V} = \frac{K_m}{V_{\text{max}}} \cdot \frac{1}{[S]} + \frac{1}{V_{\text{max}}}$ Plot 1/V 1/[S], resulting in a straight line. … Read more
Introduction to Nonlinear Pharmacokinetics explains dose-dependent absorption, metabolism, and elimination processes in drug kinetics. Introduction to Nonlinear Pharmacokinetics Pharmacokinetics (PK) studies how drugs are absorbed, distributed, metabolized, and eliminated. Typically, drug concentration follows linear PK, where drug levels are proportional to the administered dose. However, in some cases, drug kinetics deviate from this pattern, leading … Read more
Significance of Loading and Maintenance Dose Calculations in Clinical Settings ensures safe dosing, rapid action, and sustained therapy. Significance of Loading and Maintenance Dose Calculations in Clinical Settings Proper calculation of loading and maintenance doses is critical in clinical practice to ensure safe, effective, and personalized drug therapy. Key reasons include: Rapid Achievement of Therapeutic … Read more
Calculation of Loading and Maintenance Doses determines initial and sustaining doses needed to achieve and maintain therapeutic levels. Loading Dose Definition & Purpose A loading dose is an initial higher dose of a drug given to rapidly achieve the therapeutic concentration in the plasma. Useful for drugs with long half-lives, where waiting 4–5 half-lives for … Read more
