From the Guidelines
The first-line treatment for Giardia enteritis is tinidazole, which is recommended as the first choice by the 2017 Infectious Diseases Society of America clinical practice guidelines for the diagnosis and management of infectious diarrhea 1.
Treatment Options
The guidelines suggest the following treatment options for Giardia enteritis:
- Tinidazole as the first choice
- Metronidazole as an alternative option
Dosage and Administration
The dosage and administration of tinidazole and metronidazole are as follows:
- Tinidazole: approved in the United States for children aged ≥3 years, available in tablets that can be crushed
- Metronidazole: has a high frequency of gastrointestinal side effects, a pediatric suspension is not commercially available but can be compounded from tablets
Important Considerations
It is essential to note that:
- Tinidazole is approved for children aged ≥3 years
- Metronidazole is not FDA approved for the treatment of giardiasis
- Patients should be advised about proper hygiene practices to prevent reinfection and transmission
Clinical Effectiveness
Treatment with tinidazole or metronidazole is effective because these medications interfere with the parasite's ability to survive in the intestinal environment, either by disrupting DNA synthesis or inhibiting essential metabolic processes, as supported by the guidelines 1.
Patient Care
Supportive care, including adequate hydration and electrolyte replacement, is crucial, especially if diarrhea is severe. Patients should be advised to practice thorough handwashing and avoid potentially contaminated water sources to prevent reinfection and transmission.
From the FDA Drug Label
1.2 Giardiasis Tinidazole is indicated for the treatment of giardiasis caused by Giardia duodenalis (also termed G. lamblia) in both adults and pediatric patients older than three years of age [see Clinical Studies ( 14.2)] . 14. 2 Giardiasis Tinidazole (2 g single dose) use in giardiasis has been documented in 19 published reports from the world literature involving over 1,600 patients (adults and pediatric patients) In eight controlled studies involving a total of 619 subjects of whom 299 were given the 2 g × 1 day (50 mg/kg × 1 day in pediatric patients) oral dose of tinidazole, reported cure rates ranged from 80% (40/50) to 100% (15/15).
Management of Giardia enteritis can be achieved with tinidazole. The recommended dose is 2 g single dose for adults and 50 mg/kg × 1 day for pediatric patients.
- Cure rates for tinidazole in giardiasis range from 80% to 100%.
- Tinidazole is indicated for the treatment of giardiasis caused by Giardia duodenalis in both adults and pediatric patients older than three years of age 2, 2. Alternatively, nitazoxanide can be used for the treatment of diarrhea caused by Giardia lamblia 3.
From the Research
Management of Giardia Enteritis
Treatment Options
- The first-line drug treatment for giardiasis is tinidazole, which requires only a single dose to cure infection in most individuals 4, 5.
- Metronidazole is also effective, but it requires 5 to 7 days of three times a day therapy 4, 6.
- Nitazoxanide appears to be as effective as tinidazole or metronidazole, and it does not have the bitter taste of nitroimidazoles 4, 7.
- Albendazole may be of similar effectiveness to metronidazole, may have fewer side effects, and has the advantage of a simplified regimen 6.
- Tinidazole is associated with higher parasitological cure than metronidazole and albendazole 5.
- Paromomycin is a good alternate for use during pregnancy 4.
Efficacy of Treatment Options
- Tinidazole has been found to be the most effective drug for treating giardiasis in symptomatic and asymptomatic children and adults 5.
- A meta-analysis of randomized controlled trials found that tinidazole outperformed albendazole in the treatment of Giardia infections in children 8.
- The number-needed-to-treat with tinidazole to gain one additional good outcome as compared with albendazole was 4,95% CI: 3-5 8.
- Albendazole probably has fewer side effects than metronidazole, including gastrointestinal and neurological side effects 6.
Limitations of Current Treatments
- Metronidazole has been associated with significant failure rates in clearing parasites from the gut, and it is associated with poor compliance due to side effects 8.
- There is a need for a highly effective treatment for cryptosporidiosis in immunodeficient patients, but the quest for such a drug has proven to be elusive 7.
- New potentially promising drug targets in Cryptosporidium and Giardia have been identified, but there appears to be little activity toward clinical development of new drugs 7.