The term "DOTS therapy drugs" refers to the specific medications used in the Directly Observed Therapy, Short-course strategy. However, it is crucial to understand that DOTS is not just a list of drugs, but a comprehensive public health strategy that combines specific drug regimens with direct patient observation to ensure adherence. This approach was endorsed by the World Health Organization (WHO) in 1993 in response to the global tuberculosis (TB) emergency and remains a cornerstone of TB control worldwide. The primary goal is to achieve high cure rates, prevent treatment failure and relapse, and limit the development of drug-resistant strains of Mycobacterium tuberculosis.
The DOTS Drug Regimen for Drug-Susceptible TB
For most newly diagnosed cases of drug-susceptible TB, the standard short-course regimen consists of a combination of four core anti-TB drugs. The treatment is divided into two distinct phases: the intensive phase and the continuation phase.
Intensive Phase
This initial phase lasts for two months and involves the daily administration of four drugs to rapidly kill the active TB bacteria and reduce the infectiousness of the patient. The drugs typically used are:
- Isoniazid (INH): An antibacterial drug that targets the synthesis of the mycobacterial cell wall.
- Rifampin (RIF): A broad-spectrum antibiotic that inhibits bacterial RNA synthesis.
- Pyrazinamide (PZA): A medication that is effective against non-replicating bacteria within macrophages.
- Ethambutol (EMB): Used to prevent resistance from developing against isoniazid and rifampin.
Continuation Phase
Following the intensive phase, the continuation phase lasts for four to seven months, depending on the specific case. During this period, the patient continues to take isoniazid and rifampin to eliminate any remaining dormant bacteria and ensure a full cure.
The Role of Directly Observed Therapy (DOT)
Direct observation is the core component that gives DOTS its name and is critical for the strategy's success. It involves a trained healthcare worker or another designated person observing the patient swallow every dose of their prescribed medication. This oversight helps ensure that the full course of treatment is completed, which is crucial for curing the disease and preventing the emergence of drug resistance.
Direct observation can take several forms:
- In-person DOT: A healthcare worker meets the patient at a clinic, their home, or a mutually agreed-upon location.
- Electronic DOT (eDOT) or Video DOT (vDOT): The patient uses a smartphone, tablet, or computer to record or live-stream themselves taking their medication. This offers greater flexibility and reduces logistical burdens for both patients and healthcare providers.
DOTS for Drug-Resistant Tuberculosis (DOTS-Plus)
When TB strains are resistant to the standard first-line drugs, a more complex and prolonged treatment regimen, often referred to as DOTS-Plus, is required. Multidrug-resistant TB (MDR-TB) is resistant to at least isoniazid and rifampin, while extensively drug-resistant TB (XDR-TB) is even more challenging. Treatment for drug-resistant TB involves second-line drugs and newer medications, which can have more severe side effects and require careful monitoring.
Examples of newer and second-line drugs used for drug-resistant TB include:
- Bedaquiline
- Pretomanid
- Linezolid
- Moxifloxacin
- Clofazimine
Comparison of DOTS and Self-Administered Therapy
While DOTS is the standard of care for ensuring adherence, self-administered therapy (SAT) is a less intensive alternative. The comparison below highlights the differences in approach and outcomes.
| Feature | DOTS (Directly Observed Therapy) | SAT (Self-Administered Therapy) |
|---|---|---|
| Adherence Strategy | Direct observation by a healthcare worker or designated person. | Patient is responsible for taking medication without direct supervision. |
| Likelihood of Adherence | High. Observation ensures every dose is taken, especially during the crucial intensive phase. | Variable. Dependent on patient's discipline and circumstances, leading to higher rates of incomplete treatment. |
| Prevention of Resistance | High. Completion of the full course of medication prevents the emergence of drug-resistant TB. | Lower. Incomplete treatment is a major driver for the development of drug-resistant strains. |
| Patient Burden | Can be high due to regular meetings, but modern methods like eDOT reduce this significantly. | Lower daily burden, but patients may lack the social support and monitoring provided by DOT. |
| Monitoring of Side Effects | Regular contact with the observer allows for early detection and management of side effects. | Relies on the patient to report side effects, which may be missed or delayed. |
Potential Side Effects of DOTS Drugs
Patients undergoing DOTS therapy should be aware of potential adverse reactions and report them to their healthcare provider immediately.
- Isoniazid: Can cause serious issues like peripheral neuropathy (nerve damage) and hepatotoxicity (liver damage). To prevent neuropathy, patients are often given pyridoxine (vitamin B6).
- Rifampin: Can cause hepatitis, gastrointestinal upset, and a harmless reddish-orange discoloration of body fluids, including urine, sweat, and tears. It also has many drug interactions, particularly with oral contraceptives and some HIV medications.
- Pyrazinamide: Often associated with gastrointestinal upset, joint pain, and gout.
- Ethambutol: The most significant side effect is optic neuritis, which can lead to blurred vision, color vision changes, and potential vision loss. Patients must undergo regular eye exams.
Conclusion
What are dots therapy drugs? They are the core anti-tuberculosis medications—isoniazid, rifampin, pyrazinamide, and ethambutol—used in the context of the DOTS strategy. This strategy, developed by the WHO, has been instrumental in controlling the global TB epidemic by ensuring high rates of medication adherence through direct observation. While DOTS has evolved with technology, incorporating electronic observation methods to make treatment more convenient, its fundamental principle remains the same: supervised therapy leads to more effective treatment outcomes and a stronger defense against drug-resistant TB. For patients with drug-resistant strains, more complex DOTS-Plus regimens with second-line drugs are necessary, emphasizing the critical role of rigorous patient management in combating this persistent infectious disease.
This article is for informational purposes only and does not constitute medical advice. Consult a healthcare professional for diagnosis and treatment. For more information, visit the CDC website.
