Antituberculosis Drugs and Quinolones Overview

Quinolones

• Quinolones can damage growing cartilage, contraindicated under 18, pregnant, and lactating women due to secretion in milk.
• Can lead to tendon rupture.

Tuberculosis

• Infectious disease caused by Mycobacterium tuberculosis.
• Primarily affects lungs, but can affect other organs.
• Clinical features: fever, anorexia, hemoptysis, cough, sputum, weight loss, anemia, night sweats, enlarged lymph nodes, tubercle formation, necrosis, and lung fibrosis.

Antituberculosis Drugs

• First-line (standard) drugs: Isoniazid (INH), Rifampicin, Ethambutol, Streptomycin, Pyrazinamide.
• Second-line (reserve) drugs: used if first-line drugs fail or if microorganisms are resistant; Examples: Ciprofloxacin, Ofloxacin, Amikacin, Cycloserine, Ethionamide, Para-aminosalicylic acid, Capreomycin, Rifabutin.
• Drugs are typically given in combination to prevent bacterial resistance.

Isoniazid (INH)

• Mode of action: Inhibits mycolic acid synthesis in mycobacterial cell walls.
• Pharmacokinetics: Orally absorbed; absorption impaired by food (especially carbohydrates and antacids), best taken before breakfast. Serum and cerebrospinal fluid levels are similar. Metabolized in the liver by acetylation; excretion in urine (some unchanged drug). Dosage adjustment may be needed for liver impairment, but not for kidney impairment.
• Indications: Tuberculosis.
• Side effects: Hypersensitivity reactions (skin rashes, fever), hepatitis (most frequent serious side effect, risk increases with age, pregnancy, and postpartum), peripheral neuritis (caused by pyridoxine deficiency), which is correctable with pyridoxine supplementation.

Other Antituberculosis Drugs (brief overview)  

• Rifampicin: Inhibits DNA-dependent RNA polymerase; used for tuberculosis, leprosy, and meningitis prophylaxis.  Side effects: nausea, vomiting, rash, fever, harmless orange discoloration of fluids (urine, sweat, tears). Interactions with other medications may affect their effectiveness.

• Ethambutol: Inhibits RNA synthesis (prevents growth of resistant mutants).  Side effect: Retrobulbar neuritis (loss of visual acuity) and color blindness, contraindicated in children due to difficulty assessing side effects.

• Pyrazinamide: Action unknown, but likely inhibits protein synthesis in tubercle bacilli. Side effects: liver damage, gastrointestinal disturbances, allergic skin rashes, gout.

• Streptomycin: Inhibits protein synthesis (binding with 30S ribosomal subunit). Side effects: hypersensitivity reactions, cholestatic jaundice, hepatitis, vestibular nerve damage, nephrotoxicity, superinfection, interactions with other medications.

• Ethionamide: Inhibits protein synthesis in tubercle bacilli. Side effects: allergic reactions, gastrointestinal disturbances.

• Other drugs: Additional drugs are mentioned, but specifics are not elaborated on in a way that is informative enough for a summary here. 

Leprosy

• Caused by Mycobacterium leprae.
• Causes characteristic skin and peripheral nerve lesions.
• Drugs: Sulphones (e.g., dapsone), phenazines (e.g., clofazimine), anti-tubercular drugs (e.g., rifampicin), others (e.g., thiambutosine, amithiozone).

Antifungal Drugs (overview)

• Classification: Systemic (e.g. amphotericin B, flucytosine, azoles—ketoconazole, itraconazole, fluconazole, griseofulvin). Topical (e.g. nystatin, topical azoles).
• Systemic antifungal drugs: Used for systemic fungal infections. Side effects may include renal failure, hypotension, anemia, hypersensitivity.
• Topical antifungal drugs: Used for localized infections (skin, mucous membranes, vagina).

Antiprotozoal Drugs (overview)

• Malaria: Caused by Plasmodium parasites, transmitted by Anopheles mosquitoes.
• Life cycle: Includes sporozoite, liver, and erythrocytic stages.