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
- Tinidazole is approved in the United States for children aged ≥3 years and is available in tablets that can be crushed.
- Metronidazole is an alternative option, but it has a high frequency of gastrointestinal side effects and is not FDA approved for the treatment of giardiasis 1.
Dosage and Administration
- The dosage of Tinidazole for Giardia enteritis is not specified in the provided guidelines, but according to other sources, a single dose of 2 g for adults and 50 mg/kg for children is commonly recommended.
- Metronidazole is typically prescribed at 250 mg three times daily for 5-7 days for adults, or 15 mg/kg/day divided into three doses for children.
Special Considerations
- For pregnant patients, the guidelines do not specify a preferred treatment, but other sources suggest that metronidazole is generally avoided due to potential risks to the fetus.
- Patients should be advised to maintain good hydration during treatment and practice strict hand hygiene to prevent reinfection or transmission to others.
Treatment Outcomes
- Treatment failures can occur in 10-20% of cases, requiring either a longer course of the same medication or switching to an alternative agent.
- Follow-up testing is generally not necessary if symptoms resolve completely.
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).
Treatment of Giardia enteritis: Tinidazole is indicated for the treatment of giardiasis caused by Giardia duodenalis in both adults and pediatric patients older than three years of age. The recommended dose is a single 2 g oral dose, or 50 mg/kg × 1 day in pediatric patients. Reported cure rates range from 80% to 100% 2.
From the Research
Treatment Options for Giardia Enteritis
- The primary treatment for giardiasis is tinidazole, which requires only a single dose to cure infection in most individuals 3.
- Metronidazole is also effective, but it requires 5 to 7 days of three times a day therapy 3, 4.
- Nitazoxanide appears to be as effective as tinidazole or metronidazole, and it does not have the bitter taste of nitroimidazoles 3.
- Albendazole may be of similar effectiveness to metronidazole, may have fewer side effects, and has the advantage of a simplified regimen 5.
- Paromomycin is a good alternate for use during pregnancy, as it is not systematically absorbed 3, 4.
Efficacy of Treatment Options
- Tinidazole was associated with higher parasitological cure than metronidazole and albendazole 6.
- A single dose of tinidazole was found to be the most effective drug for treating giardiasis in symptomatic and asymptomatic children and adults 6.
- Combination treatment with a 5-nitroimidazole and a benzimidazole is more effective than repeated courses of 5-nitroimidazole or monotherapies in refractory cases 7.
Refractory Giardiasis
- The prevalence of treatment refractory giardiasis is increasing, with 5-nitroimidazole refractory infection occurring in up to 50% of cases 7.
- Quinacrine is effective in refractory cases, but potentially severe side effects limit its use 7.
- A combination of a 5-nitroimidazole and albendazole or mebendazole, and quinacrine monotherapy, are rational choices in nitroimidazole refractory infections, but randomized controlled studies are needed 7.