antitubercular meds

TB

• caused by mycobacterium tuberculosis; slow growing, acid-fast rod

• characterized by granulomas (inflamm cells)

  • have cheesy or caseated consistency

• most comm found in lungs; can be found in cerebral cortex, growing ends of bones

• less comm found in liver, kidney, and GI tract

how is TB passed

• from infected humans, cows (bovine), and birds (avian)

• transmitted by droplets

what is TB more comm in

• homeless

• immunosuppressed

• elderly

• drug/alcohol abusers

• lower socioeconomic status

• crowded areas

dx of TB

step 1: tuberculin skin test

step 2: chest x-ray

step 3: sputum culture

step 1: TB skin test

• Mantoux test; also called PPD

• Read 48-72 hours for induration in mm

• if positive (> 5 mm), moves to step 2

• positive indicates exposure to TB; latent carrier or active

step 2: chest x-ray

• To rule out active TB, if chest x-ray positive, moves to step 3

step 3: sputum culture

• To confirm the presence of MTB 

• 3 samples (early morning) on consecutive days

• 2-8 weeks to get definitive results (Gold standard)

• **May use AFB stain or NAAT for faster results

drug therapy - general

• 2 lines of drugs

• intended response - prophylaxis and tx; reduce cough, sputum production, and fatigue; want to end up with negative sputum culture

• 2 phases of tx - usually lasts 6 mths

  • induction (2 mths) - eliminate actively dividing tubercle bacilli

  • continuation (4 mths) - eliminate intracellular “persisters”; after initial 2 months, they start to adjust doses of meds; dosing is going to be daily or intermittent; assess liver fx, preg, and drug resistance

• need to determine drug sensitivity b4 tx

• comm given in combo

meds given during induction phase of tx

Isoniazid, Rifampin, Pyrazinamide, Ethambutol (RIPE)

s/e of TB drugs general

• GI Effects (n/v, loss of appetite, abdominal discomfort)

• Fatigue 

• Weight gain

general adverse of TB meds

• Hepatotoxicity - risk increases with >35 who drink alcohol and who have other liver diseases

• Drug induced hepatitis - major risk because all these drugs are metabolized in liver; most common adverse

general pt teaching for TB meds

• baseline liver labs (LFT) and q2-3 mths - higher rx for liver toxicity and gout in elderly

  • assess for jaundice, dark urine, fatigue, abd pain

• DOT used to ensure adherence to regimen

• take meds as directed even when s/s subside - most drugs peak at 2-4 hrs and stay in system for 24 hrs; so take at same time everyday, pref at bedtime to avoid n/v

• avoid direct sunlight & use sunscreen and protective clothes

• avoid alcohol

• call HCP when - jaundice, extreme fatigue, severe abd pain, uncontrolled n/v

Isoniazid (INH)

• mainstay of tx - 1st line

• first drug given for TB; most widely used

• Given alone for prophylaxis or in combo with other drugs for tx

• In order for INH to work, it has to be activated; when it enters TB cell, it is activated by CATG enzyme

• MOA - Inhibits cell wall synthesis and interferes with metabolism

INH s/e

• Lupus-like syndrome – joint pain, fever (rare), rash

• Seizures – in overdose or if vitamin B6 is low

• Psychiatric symptoms - mood changes, memory issues

INH adv effects

• Peripheral Neuropathy caused by Vitamin B6 deficiency; more common with DM, alcoholism, malnutrition; tx by giving B6

• Hyperglycemia 

INH drug interactions

• antacids

• Rifampin - Assess benefits vs. risk for giving together and the reaction it may cause; given together bc they kill bacteria in different ways, making the combo more effective, and helps prevent drug resistance

nursing considerations INH

• Black Box Warning related to hepatotoxicity - HCP closely monitor LFT’s

pt teaching INH

• Pyridoxine (vitamin B6) to help with neuropathy

rifampin

• 1st line - given alone for prophylaxis or in combo w/ other meds for tx

• MOA - Inhibits protein synthesis

  
  

rifampin s/e

• Discoloration of body fluids and feces - orange/red discoloration; harmless; pts become alarmed by it

• Flu-like symptoms 

rifampin adv effects

• Anemia due to immune reaction (can trigger immune system to attack its own cells hemolytic anemia; more often with intermittent or missed doses) and blood cell production

• can cause bone marrow suppression; rare but life-threatening, so needs to be stopped immediately if occurs

rifampin drug interactions

many bc drug breaks down faster

• Oral contraceptives - decreases effectiveness

• HIV meds (protease inhibitors, NNRTIs) - lower levels of HIV meds

• Blood thinners (warfarin) - decrease effectiveness; increasing clotting risks

• Seizure medications (phenytoin, valproate) - decreases effectiveness 

• Immunosuppressants (cyclosporine) - decreases effectiveness; increases risk for organ rejection for those with transplants

• Methadone - decreases methadone levels; increases chance for withdrawal symptoms

• Antipsychotics/Antidepressants - decreases effectiveness

nursing considerations for rifampin

• Thorough assessments (especially characteristics of sputum and lung sounds)

• Assess for anemia

pt teaching rifampin

• Expect body fluid color changes; can stain skin, clothing, contact lenses

pyrazinamide

• 1st line - given in combo for tx

• MOA - inhibit fatty acid synthesis; kills TB bacteria, esp in immune cells, where it is more acidic

pyrazinamide s/e

• Gout - symptomatic consequence of hyperurecemia; more often in pts with hx of gout or with predisposition to gout

• Arthralgia (joint pain) - may be different than gout pain; typically associated with uric deposit and inflammation

• Photosensitivity

pyrazinamide adv effects

• Nephrolithiasis - pyrazinide acid competes with uric acid for renal tubule secretion; it reduces the uric acid excretion (it overtakes it); leads to high uric acid in blood and urine, which can crystallize and form the stones

• Hyperuricemia - occurs in high % of pts

• Hepatotoxicity - Most heptatoxic of the four drugs

pryazinamide drug interactions

anti-gout meds

nursing considerations pyrazinamide

• Monitor uric acid levels 

• Complete adequate urinary assessments & musculoskeletal assessment

• BUN/Cr can increase if there are obstructions from stones

pt teaching pyrazinamide

• Report s/s of hepatotoxicity 

• Report changes in urination and back/flank pain

• Drink lots of fluids (at least 3L/day) to help clear uric acid out; avoid cola-colored, carbonated, sweet tea; stay with clear fluids

ethambutol

• 1st line - given in combo for tx

• least hepatotoxic

• moa - inhibits growth of mycobacteria

ethambutol adv effect

optic neuritis (inflammation of optic nerve) - very dose dependent; typically with higher doses; can develop blurred vision, decreased visual acuity, loss of red-green discrimination; usually reversible if the drug is stopped early enough; typically occurs in both eyes, not just one

ethambutol drug interactions

• Antacids - specifically those that contain aluminum 

• Other drugs with ocular toxicity (Hydroxychloroquine, linezolid, some antiretrovirals) - can increase optic neuritis

• Drugs that affect kidney function (Aminoglycosides, NSAIDs [long-term])

nursing considerations ethambutol

• Not recommended for pediatrics under age 13

• Cleared through kidneys, so if someone has impaired kidney function, the levels of the drug are going to increase in the body, increasing risk of optic neuritis/toxicity

ethambutol pt teaching

routine eye exams

fluroroquinolones: bedaquiline

• 2nd line - approved for multi-drug resistant tb

• moa - Blocks mycobacterial ATP synthesis needed to make energy, so cell can’t grow

bedaquiline s/e

• GI effects - n/v

• headache

• fatigue

• joint pain

• chest pain

bedaquiline adv effect

prolonged QT - increases rx of arrhythmias

bedaquiline drug interactions

• Strong CYP3A4 Inducers (Rifampin, Rifapentine, Carbamazepine, Phenytoin) & CYP3A4 Inhibitors (Ketoconazole, Clarithromycin) - make bedaquline less effective

• Drugs that Prolong QT Interval (Azithromycin, fluoroquinolones, macrolides, antipsychotics, some antiarrhythmics) - increases chance for arrhythmias

nursing considerations bedaquilinie

• Not recommended for pediatrics under age 13

• Pregnancy category B

• Black box warning - arrhythmias; life-threatening

• Assessing pt frequently; chest pain

• Regular EKGs

• Baseline LFTs and regular checks

bedaquiline pt teaching

need to follow up with HCP on regular basis