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Watch for Drug Induced Hapatitis

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https://www.webmd.com/drugs/2/drug-8665/isoniazid-oral/details
Used with other meds to treat TB. Used alone to prevent TB infections in those who may be infectes. Works by stopping growth of bacteria.
Take on empty stomach 1 hour before or 2 hours after meals. Of take antacids, take 1 hour before taking antacids.
Dosage based on age, weight, medical condition, and reaponse to treatment. Take at evenly spaced times at the same time each day. Take until all the medicine is finished.
May cause nerve issues so doctor may request taking Ba6 to counteract that side effect.

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isoniazid

General

Genetic Implications:

Pronunciation:
eye-soe-nye-a-zid

Trade Name(s)

INH

Isotamine [Canada]

Pregnancy Category
Category C

Ther. Class.
antituberculars

Indications

First-line therapy of active tuberculosis, in combination with other agents.

Prevention of tuberculosis in patients exposed to active disease (alone).

Action

Inhibits mycobacterial cell wall synthesis and interferes with metabolism.

Therapeutic Effect(s):

Bacteriostatic or bactericidal action against susceptible mycobacteria.

Pharmacokinetics

Absorption: Well absorbed following PO/IM administration.

Distribution: Widely distributed; readily crosses the blood-brain barrier. Crosses the placenta; enters breast milk in concentrations equal to plasma.

Protein Binding: 10–15%.

Metabolism and Excretion: 50% metabolized by the liver by N-acetyltransferase  (rate of acetylation is genetically determined [slow acetylators have ↑ isoniazid levels and ↑ risk of toxicity; fast acetylators have ↓ isoniazid levels and ↑ risk for treatment failure]); 50% excreted unchanged by the kidneys.

Half-life: 1–4 hr in patients with normal renal and hepatic function; 0.5–1.6 hr in fast acetylators; 2–5 hr in slow acetylators.

TIME/ACTION PROFILE (blood levels)

ROUTEONSETPEAKDURATION
PO | rapid | 1–2 hr | up to 24 hr
IM | rapid | 1–2 hr | up to 24 hr

Contraindication/Precautions

Contraindicated in:

Hypersensitivity;

Acute liver disease;

History of hepatitis from previous use.

Use Cautiously in:

History of liver damage or chronic alcohol ingestion;

Black and Hispanic women, women in the postpartum period, or patients >50 yr (↑ risk of drug-induced hepatitis);

Severe renal impairment (dose ↓ may be necessary);

Malnourished patients, patients with diabetes, or chronic alcoholics (↑ risk of neuropathy);

OB:  Lactation:  Although safety is not established, isoniazid has been used with ethambutol to treat tuberculosis in pregnant women without harm to the fetus.

Adverse Reactions/Side Effects

CNS: psychosis, seizures

EENT: visual disturbances

GI: DRUG-INDUCED HEPATITIS, nausea, vomiting

Derm: rashes

Endo: gynecomastia

Hemat: blood dyscrasias

Neuro: peripheral neuropathy

Misc: fever

* CAPITALS indicate life-threatening.
Italics indicate most frequent.

Interactions

Drug-Drug

Additive CNS toxicity with other  antituberculars .

BCG vaccine may not be effective during isoniazid therapy.

Isoniazid ↓ metabolism of and may ↑ levels of  phenytoin .

Aluminum-containing antacids may ↓ absorption.

Psychotic reactions and coordination difficulties may result with disulfiram .

Concurrent administration of  pyridoxine may prevent neuropathy.

↑ risk of hepatotoxicity with other  hepatotoxic agents including  alcohol , acetaminophen and  rifampin .

Isoniazid may ↓ blood levels and effectiveness of ketoconazole .

May ↑  carbamazepine levels and risk of hepatotoxicity.

May ↓ effectiveness of  clopidogrel (avoid concurrent use).

Drug-Food:

Severe reactions may occur with ingestion of foods containing high concentrations of tyramine (see food sources for specific nutrients).

Route/Dosage

PO:  IM: (Adults) 300 mg/day (5 mg/kg) or 15 mg/kg (up to 900 mg) 2–3 times weekly.

PO:  IM: (Children <40 kg): Latent TB infection –10–20 mg/kg/day (up to 300 mg/day) or 20–40 mg/kg (up to 900 mg) 2 times weekly; Active TB infection– 10–15 mg/kg/day (up to 300 mg/day) or 20–40 mg/kg (up to 900 mg) 2 times weekly.

Availability (generic available)

Tablets: 100 mg, 300 mg

Oral solution (orange, raspberry flavor): 50 mg/5 mL

Injection: 100 mg/mL

In Combination with: rifampin (Rifamate); rifampin and pyrazinamide (Rifater). See combination drugs.

Assessment

Mycobacterial studies and susceptibility tests should be performed prior to and periodically throughout therapy to detect possible resistance. About 50% to 65% of Caucasians, Black, South Indians and Mexicans are slow acetylators at risk for toxicity, while 80 to 90% of Eskimos, Japanese, and Chinese are rapid acetylators at risk for decreased levels and treatment failure.

Lab Test Considerations:

Hepatic function should be evaluated prior to and monthly throughout therapy. Increased AST, ALT, and serum bilirubin may indicate drug-induced hepatitis. Black and Hispanic women, postpartal women, and patients >50 yr are at highest risk. Risk is lower in children; therefore, liver function tests are usually ordered less frequently for children.

Toxicity Overdose:

If isoniazid overdosage occurs, treatment with pyridoxine (vitamin B) is instituted.

Potential Diagnoses

Risk for infection (Indications)

Noncompliance (Patient/Family/Teaching)

Implementation

PO:  May be administered with food or antacids if GI irritation occurs, although antacids containing aluminum should not be taken within 1 hr of administration.

IM: Medication may cause discomfort at injection site. Massage site after administration and rotate injection sites.

Solution may form crystals at low temperatures; crystals will redissolve upon warming to room temperature.

Patient/Family Teaching

Advise patient to take medication as directed. Take missed doses as soon as possible unless almost time for next dose; do not double up on missed doses. Emphasize the importance of continuing therapy even after symptoms have subsided. Therapy may be continued for 6 mo–2 yr.

Advise patient to notify health care professional promptly if signs and symptoms of hepatitis (yellow eyes and skin, nausea, vomiting, anorexia, dark urine, unusual tiredness, or weakness) or peripheral neuritis (numbness, tingling, paresthesia) occur. Pyridoxine may be used concurrently to prevent neuropathy. Any changes in visual acuity, eye pain, or blurred vision should also be reported immediately.

Caution patient to avoid the use of alcohol during this therapy, as this may increase the risk of hepatotoxicity. Ingestion of Swiss or Cheshire cheeses, fish (tuna, skipjack, and sardinella), and possibly tyramine-containing foods (see food sources for specific nutrients) should also be avoided, as they may result in redness or itching of the skin; hot feeling; rapid or pounding heartbeat; sweating; chills; cold, clammy feeling; headache; or light-headedness.

Emphasize the importance of regular follow-up physical and ophthalmologic exams to monitor progress and to check for side effects.

Evaluation/Desired Outcomes

Resolution of signs and symptoms of tuberculosis.

Negative sputum cultures.

Prevention of activation of tuberculosis in persons known to have been exposed.

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Class: antituberculars

[indications]
-1st line therapy for TB in combinations with other agents
- prevention for people exposed to active disease

[Actions]
-inhibits mycobacterium wall sytgesisband interferes with metabolism
- therapeutic~ bacteriocidal action against against susceptible mycobacteria

[Absorption]
- we’ll absorbed following po/IM administration

[Metabolism and excretion}
- 50% metabolized by liver
-50% excreted by kidney unchanged

[half-life]
- 1-4 hours

[Side effects]
- n/v, rash, peripheral neuropathy, fever, psychosis, seizures, visual disturbances

[Assessment]
- Hepatic function should be monitored prior to and monthly throughout therapy
- increased ALT, AST, and serum bilirubin May indicate drug induced hepatitis

[Toxicity and Overdose]
- treatment with pyridoxine (vit B) is instituted

[Implementation]
- P.O.~ May be given with food or antacids if stomach upset occurs
-IM~ massage after injection

[Teaching]
- take as directed. If dose is missed take as soon as possible unless close to next dose NEVER double up in doses and DO NOT stop medication if symptoms subside.
- Ifsymptoms of hepatitis occur ( yellow eyes and skin, n/v, dark urine, unusual tiredness/weakness) notify healthcare professional.
- caution patient to avoid alcohol use during therapy as this may increase risk of hepatotoxicity.

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INH-Isoniazid