Pharmacology - NAPLEX

Sequential folate synthesis inhibition (DHPS then DHFR). The combination synergistically blocks tetrahydrofolate production, essential for bacterial nucleotide synthesis and growth.

Inhibit DNA gyrase (topoisomerase II) and topoisomerase IV. Fluoroquinolones interfere with bacterial DNA replication and repair by targeting enzymes essential for supercoiling and decatenation.

Potentiates antithrombin to inhibit thrombin (IIa) and factor Xa. Heparin enhances the activity of a natural anticoagulant, rapidly inactivating key clotting factors to prevent thrombus formation.

Bind $50S$ ribosome to inhibit translocation and protein synthesis. Macrolides prevent the movement of the peptidyl-tRNA from the A site to the P site during translation elongation.

Irreversibly bind $30S$ ribosome causing misreading and bactericidal effect. Aminoglycosides disrupt protein synthesis by interfering with mRNA reading on the ribosome, resulting in faulty proteins and bacterial death.

Binds $D$-Ala-$D$-Ala to inhibit peptidoglycan cell wall synthesis. Vancomycin targets the terminal dipeptide in peptidoglycan precursors, halting cell wall assembly in Gram-positive bacteria.

Inhibit PBPs (transpeptidases) to block bacterial cell wall cross-linking. Beta-lactams weaken bacterial cell walls by preventing the final cross-linking step in peptidoglycan synthesis, leading to cell lysis.

Binds ergosterol to form membrane pores causing cell leakage. Amphotericin B creates channels in fungal membranes, allowing leakage of cellular contents and leading to cell death.

Irreversibly blocks P2Y12 (ADP) receptor to inhibit platelet aggregation. Clopidogrel prevents ADP-mediated activation of glycoprotein IIb/IIIa, crucial for platelet cross-linking and clot formation.

Inhibit ACE, decreasing angiotensin II and increasing bradykinin. ACE inhibitors reduce vasoconstriction and sodium retention while potentiating a vasodilatory peptide, lowering blood pressure.

Guanosine analog; inhibits viral DNA polymerase after phosphorylation. Acyclovir mimics a nucleoside and, once activated by viral thymidine kinase, terminates DNA chain elongation in herpes viruses.

Four-factor PCC plus vitamin K (phytonadione). This combination rapidly replenishes vitamin K-dependent factors and supports long-term correction of coagulopathy.

Irreversibly inhibits COX-1, decreasing thromboxane A2. Aspirin suppresses platelet activation by reducing a pro-aggregatory eicosanoid, providing antithrombotic effects.

Protamine sulfate. Protamine neutralizes heparin's anticoagulant effect by forming a stable complex, restoring normal clotting.

Block angiotensin II type 1 (AT1) receptors. ARBs prevent angiotensin II from binding its receptor, mitigating vasoconstriction and aldosterone release without affecting bradykinin.

Inhibit NaCl cotransporter in distal convoluted tubule. Thiazides promote diuresis by blocking sodium reabsorption in the distal nephron, reducing blood volume and pressure.

Inhibit Na-K-2Cl cotransporter in thick ascending limb. Loop diuretics cause potent natriuresis by inhibiting salt transport in the loop of Henle, decreasing extracellular fluid volume.

Aldosterone receptor antagonist in collecting duct (potassium-sparing). Spironolactone blocks mineralocorticoid effects, reducing sodium reabsorption while preserving potassium in the distal nephron.

Decreases hepatic gluconeogenesis and increases insulin sensitivity. Metformin improves glycemic control by suppressing liver glucose output and enhancing peripheral glucose uptake.

Close pancreatic KATP channels to increase insulin release. Sulfonylureas stimulate beta cells by blocking potassium efflux, depolarizing the membrane and triggering insulin secretion.

Inhibit HMG-CoA reductase to decrease hepatic cholesterol synthesis. Statins lower LDL cholesterol by blocking the rate-limiting step in the mevalonate pathway, upregulating LDL receptors.

Competitive opioid receptor antagonist (highest affinity for $\mu$). Naloxone reverses opioid effects by competitively displacing agonists from receptors, particularly the mu subtype involved in analgesia and respiratory depression.

Inhibit $14$-$\alpha$-demethylase to reduce ergosterol synthesis. Azoles disrupt fungal membrane integrity by inhibiting a key enzyme in the ergosterol biosynthetic pathway.

Neuraminidase inhibitor that blocks influenza virion release. Oseltamivir prevents sialic acid cleavage, trapping new influenza viruses on the host cell surface and limiting spread.