The Major Problems in Tuberculosis Management
Pharmacological management of tuberculosis is a crucial issue since the disease is rather widespread, and many patients are drug-resistant (Woo, 2016). What is more, there is not enough research on TB medicines, which leads to unsatisfactory patient outcomes (Alsultan & Peloquin, 2014). Multiple-drug-resistant (MDR) TB has become one of the major problems in the healthcare system (Woo, 2016). Thus, researchers and healthcare specialists work hard to analyze the pharmacokinetics, pharmacodynamics, and adverse effects of various anti-TB drugs.
Isoniazid (INH)
INH is a synthetic agent the main features of which are carboxylic acid hydrazide and pyridine nucleus. INH helps to block the mycolic acid synthesis (Alsultan & Peloquin, 2014). The drug has good absorption from intramuscular injection sites and the gastrointestinal tract. Oral absorption is decreased by food, so it is recommended to take the medicine on an empty stomach (Alsultan & Peloquin, 2014).
Rifampicin (RIF)
Rifampicin has excellent sterilizing activity, which enables assigning short-course regimens (Alsultan & Peloquin, 2014). Some research indicates that the drug is highly dose-dependent. RIF resistance develops from single amino acid substitutions in the RNA polymerase’s beta subunit (Alsultan & Peloquin, 2014). In some cases, reduced or delayed absorption of RIF may occur. The most common conditions for such an event are HIV, diabetes mellitus, previous gastrointestinal surgery, and cystic fibrosis (Alsultan & Peloquin, 2014).
Rifabutin (RBN)
This medicine is highly recommended for HIV patients due to the possibility of an easy combination with anti-HIV drugs. RBN is subjected to extensive intestinal and hepatic metabolism (Alsultan & Peloquin, 2014). Over 20 metabolites have been discovered, the major one being 25-desacetyl-RBN. What concerns drug interaction, RBN can induce CYP1A2, CYP2D6, the sulfotransferase and glucuronosyltransferase of the phase II enzymes, and the efflux transporter P-glycoprotein (Alsultan & Peloquin, 2014).
Ethambutol (EMB)
Research indicates that the absorption of EMB is variable (Alsultan & Peloquin, 2014). The highest concentrations of 2–6 μg/mL have been recorded in 2-3 hours after oral doses.
The most common trigger of resistance is presented by mutations in the embB region, particularly codon 306. The major adverse event is optic neuritis (Alsultan & Peloquin, 2014). EMB should not be prescribed together with antacids and presumably
Iron, sucralphate, or other drugs incorporating di – or trivalent cations.
An Innovative Approach: Bedaquiline
During research, there were some apprehensions regarding bedaquiline since the mortality rate in the experiment group was higher than in the placebo group. However, since FDA-reviewed applications are frequently contingent on complex risk-benefit assessments, the drug was approved (Cox & Laessig, 2014). The endorsement was performed under the FDA’s “accelerated-approval regulations” that allow the authorization of drugs for “serious or life-threatening conditions that provide meaningful therapeutic benefit over existing therapies” (Cox & Laessig, 2014, p. 689). Bedaquiline has the capability of retaining activity against some M. tuberculosis isolates that are immune to other medicines due to having a different mechanism.
Drug Therapy for Drug-Resistant TB
If a patient is resistant to INH on a nine-month regimen, the drug should be discontinued. If there was EMB in the primary regimen, then the treatment with EMB and INH should be carried on for 12 months. In case a patient has resistance to many first-line medicines, a minimum of three new drugs to which the organism is susceptible should be applied (Woo, 2016).
Nursing Implications
The major nursing-related consequence of TB treatment is reaching a positive outcome. At the same time, nurses should be alert and thoroughly check patients results in order to evaluate the risk of co-morbidity and come up with an alternative treatment approach when needed (Bell, 2014). Nurses also provide support to families and educate patients on adverse effects so that together they could avoid complications.
References
Alsultan, A., & Peloquin, C. A. (2014). Clinical pharmacology of the anti-tuberculosis drugs. In P. D. O. Davies, S. B. Gordon, & G. Davies (Eds.), Clinical tuberculosis (5th ed.) (pp. 209-228). Boca Raton, FL: CRC Press.
Bell, C. E. (2014). The role of the tuberculosis nurse specialist. In P. D. O. Davies, S. B. Gordon, & G. Davies (Eds.), Clinical tuberculosis (5th ed.) (pp. 405-415). Boca Raton, FL: CRC Press.
Cox, E., & Laessig, K. (2014). FDA approval of bedaquiline — The benefit–risk balance for drug-resistant tuberculosis. New England Journal of Medicine, 371(8), 689-691.
Woo, T. M. (2016). Tuberculosis. In T. M. Woo & M. V. Robinson (Eds.), Pharmacotherapeutics for advanced practice nurse prescribers (4th ed.) (pp. 1237-1252). Philadelphia, PA: F. A. Davis Company.