Blood Coagulation and Anemia Overview

Blood Coagulation

• Clots are dissolved by plasmin, which is formed from plasminogen.
• Anticoagulants prevent blood clotting by interfering with various stages of the process.
• Thrombolytic drugs dissolve existing clots by activating the plasminogen system.
• Hemostatic drugs stop bleeding by replacing clotting factors or preventing clot dissolution.
• Hemophilia is a genetic disorder characterized by excessive bleeding due to a lack of clotting factors.

Anemia

• Blood consists of plasma and formed elements (RBCs, WBCs, and platelets).
• Erythropoiesis, the production of RBCs in the bone marrow, is regulated by erythropoietin, a glycoprotein produced by the kidneys.
• RBCs have a lifespan of around 120 days and are recycled after lysis.
• Iron deficiency anemia results from inadequate iron intake or absorption, leading to decreased hemoglobin production and oxygen carrying capacity.

Diuretics

• Loop diuretics are potent diuretics that block reabsorption of sodium and chloride in the loop of Henle.
• Carbonic anhydrase inhibitors block carbonic acid and bicarbonate formation in the renal tubule, resulting in alkaline urine and loss of bicarbonate buffer.
• Potassium-sparing diuretics are mild diuretics that conserve potassium while promoting sodium and water excretion.
• Osmotic diuretics like mannitol use hypertonic pull to remove fluid from the intravascular spaces and promote diuresis.

Urinary Tract

• Urinary tract anti-infectives include antibiotics effective against gram-negative bacteria and drugs that acidify urine to kill bacteria.
• Urinary tract antispasmodics relieve urinary tract spasms by blocking parasympathetic activity and relaxing muscles.
• Phenazopyridine is a urinary tract analgesic that relieves symptoms of irritation, burning, urgency, and pain.

Respiratory System

• The upper respiratory tract has protective features like hairs, mucus, cilia, and cough/sneeze reflexes.
• Alveoli are the sites of gas exchange, producing surfactant to reduce surface tension.
• Respiration is controlled by the medulla and involves a balance between the sympathetic and parasympathetic systems.
• Inflammation of the upper respiratory tract can lead to conditions like the common cold, rhinitis, sinusitis, pharyngitis, and laryngitis.
• Obstructive disorders like asthma, COPD, cystic fibrosis, and respiratory distress syndrome interfere with air delivery to the alveoli.

Drugs Acting on the Upper Respiratory Tract

• Antitussives suppress cough by acting centrally or locally.
• Decongestants cause vasoconstriction and reduce blood flow to irritated nasal membranes, potentially leading to rebound vasodilation (rhinitis medicamentosa).
• Topical nasal steroids block inflammation and are preferred for allergic rhinitis.
• Antihistamines block histamine at H1 receptors, reducing allergic response.
• Expectorants liquefy lower respiratory tract secretions.
• Mucolytics break down mucus, aiding expectoration.

Drugs Acting on the Lower Respiratory Tract

• Pulmonary obstructive diseases like asthma and COPD obstruct major airways, while RDS affects the alveoli.
• Xanthine derivatives directly affect smooth muscle in the respiratory tract and blood vessels.

Drugs Affecting the Female Reproductive System

• Abortifacients stimulate uterine activity to induce abortion or evacuation after fetal death.
• Tocolytics relax uterine smooth muscle to prevent premature labor, with hydroxyprogesterone caproate being the only approved drug in the US.

Drugs Affecting the Male Reproductive System

• Androgens are male sex hormones responsible for male characteristics and secondary sex characteristics.
• Anabolic steroids are testosterone analogues with greater protein-building effects than androgenic effects, often abused for performance enhancement with potentially deadly consequences.
• Penile erectile dysfunction is treated with alprostadil (injected) and PDE5 inhibitors (oral), which enhance vascular filling of the corpus cavernosum.