Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
POVAN vs FLEXERIL
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Pyrvinium pamoate inhibits oxidative metabolism and glucose uptake in susceptible helminths, leading to energy depletion and paralysis of the worm. It also binds to DNA and inhibits RNA synthesis in the parasite.
Cyclobenzaprine is a centrally acting muscle relaxant that acts primarily at the brainstem, reducing tonic somatic motor activity via inhibition of descending serotonergic pathways. It is structurally related to tricyclic antidepressants and exhibits anticholinergic, sedative, and analgesic effects.
Treatment of enterobiasis (pinworm infection) caused by Enterobius vermicularis
Adjunct to rest and physical therapy for relief of muscle spasm associated with acute, painful musculoskeletal conditions (FDA-approved),Off-label: Fibromyalgia, chronic muscle spasm, tension headaches, and as a sleep aid
Pyrantel pamoate: 11 mg/kg (maximum 1 g) orally once; repeat in 2 weeks for pinworm. For ascariasis, hookworm, trichostrongyliasis: 11 mg/kg (max 1 g) once daily for 3 days.
10 mg to 15 mg orally three times a day; maximum daily dose: 30 mg.
Terminal elimination half-life is approximately 16 hours; clinically, this supports single-dose administration with slow elimination
Terminal elimination half-life is 18 hours (range 8–37 hours) with clinical context: requires dose adjustment in hepatic impairment; steady-state reached in ~3–5 days.
Pyrvinium pamoate is minimally absorbed from the gastrointestinal tract; systemic metabolism is negligible. The small absorbed fraction is metabolized in the liver, but specific enzymes are not well defined.
Primarily hepatic via CYP3A4, CYP1A2, and CYP2D6; undergoes N-demethylation and glucuronidation. Active metabolite: norcyclobenzaprine.
Primarily fecal (90%) as unchanged drug via bile; renal excretion is minimal (<1%)
Primarily hepatic; approximately 50% excreted in urine as metabolites, less than 1% unchanged; 40% excreted in feces via bile.
Bound to plasma proteins (especially albumin) approximately 75–80%
~93% bound to plasma proteins, primarily albumin.
Apparent volume of distribution is 0.5–0.7 L/kg, consistent with moderate tissue distribution
~14 L/kg (range 10–20 L/kg), indicating extensive tissue distribution.
Oral bioavailability is low (<10%) due to poor absorption; acts topically in the GI tract
Oral: ~33% due to extensive first-pass metabolism.
No specific guidelines; caution in severe renal impairment (Cr Cl <30 m L/min) due to limited data.
No specific dosage adjustment guidelines; use with caution in renal impairment due to potential for increased side effects.
Contraindicated in acute hepatic disease or significant liver impairment (Child-Pugh class B or C); use not recommended.
Contraindicated in hepatic impairment; Child-Pugh class A, B, C: no safe dosage established.
Weight-based: 11 mg/kg (maximum 1 g) orally once for pinworm; repeat in 2 weeks. For other infections: 11 mg/kg once daily for 3 days.
Not recommended for use in children under 15 years old; safety and efficacy not established.
No specific adjustments; use standard dosing with caution due to potential comorbidities and reduced hepatic function.
Use lower starting dose (e.g., 5 mg) and titrate slowly; increased risk of sedation and anticholinergic effects. May not be well tolerated; consider alternative therapy.
None
None
Gastrointestinal disturbances may occur; caution in patients with inflammatory bowel disease or severe hepatic impairment. May cause staining of stools and emesis. Avoid in pregnancy unless clearly needed.
Should not be used for longer than 2-3 weeks (acute use only),May impair mental or physical abilities required for driving or operating machinery,Central nervous system depression additive with alcohol and other CNS depressants,Anticholinergic effects: caution in patients with angle-closure glaucoma, urinary retention, or prostatic hypertrophy,Cardiovascular effects: risk of arrhythmias, especially in patients with preexisting cardiac disease (tachycardia, QT prolongation),Serotonin syndrome risk when used with MAOIs, SSRIs, SNRIs, or other serotonergic drugs,Hepatic impairment: lower doses recommended
Hypersensitivity to pyrvinium or any component of the formulation,Intestinal obstruction or acute abdominal conditions
Concurrent use of MAOIs or within 14 days of MAOI therapy,Acute recovery phase of myocardial infarction,Arrhythmias, heart block, or congestive heart failure,Hyperthyroidism
No specific food interactions. The drug should be taken with food to reduce gastrointestinal upset.
Alcohol should be avoided due to additive CNS depression. No specific food interactions; take with or without food. Grapefruit juice does not significantly interact, but caution with high-fat meals may alter absorption slightly.
Pyrvinium pamoate (Povan) is not recommended during pregnancy due to insufficient human data. Animal studies have not shown teratogenicity, but risk cannot be excluded. In first trimester, avoid use unless clearly needed. Second and third trimester: consider risk-benefit; no known fetal harm from limited reports.
Pregnancy Category B. Animal studies have not demonstrated fetal risk, but no adequate human studies in pregnant women. Use only if clearly needed. First trimester: no known risk. Second trimester: no known risk. Third trimester: potential for neonatal adverse effects such as respiratory depression and withdrawal if used near term.
Unknown if pyrvinium pamoate is excreted in human milk. M/P ratio not available. Caution advised, consider alternative treatment during breastfeeding.
Excreted in breast milk in small amounts (M/P ratio not established). Clinical relevance uncertain; however, due to potential for adverse effects in nursing infants, caution is advised. Alternative therapies preferred, especially when nursing a premature or low-birth-weight infant.
No dose adjustment studied in pregnancy. Standard adult dose: 5 mg/kg base (max 350 mg) single dose. Use only if potential benefit justifies risk.
No specific dosing adjustments recommended for pregnancy. Use lowest effective dose and shortest duration due to potential neonatal effects. Pharmacokinetics may be altered in pregnancy; however, no dose adjustment guidelines exist.
POVAN (pyrvinium pamoate) is primarily used for enterobiasis (pinworm infection). Administer as a single oral dose; repeat after 2 weeks to prevent reinfection. Tablets should be swallowed whole to avoid staining teeth. Drug may turn stools red. Avoid in patients with gastrointestinal disorders or inflammatory bowel disease. Monitor for nausea, vomiting, and cramping.
Flexeril (cyclobenzaprine) is structurally related to tricyclic antidepressants (TCAs) and shares similar anticholinergic and sedative properties. It should not be used longer than 2-3 weeks due to lack of evidence for efficacy beyond that duration. Avoid in patients with hyperthyroidism, heart block, or recent MI. Concomitant use with MAOIs can cause hypertensive crisis. Onset of muscle relaxation is delayed; therapeutic effect may not be apparent until after 2-4 days. Sedation is the most common side effect and can be used to aid sleep.
Take the medication exactly as a single dose, and repeat after 2 weeks.,Swallow tablets whole; do not crush or chew to prevent mouth staining.,Stools may appear bright red; this is harmless.,Wash hands thoroughly after using the toilet and before eating to prevent reinfection.,Wash bedding and underwear in hot water; vacuum floors to remove eggs.,Treat all household members simultaneously to avoid spread.,Report persistent abdominal pain or diarrhea to your doctor.
Do not take for longer than 3 weeks unless directed by your doctor.,This medication may cause drowsiness or dizziness; avoid driving or operating heavy machinery until you know how it affects you.,Avoid alcohol and other CNS depressants (e.g., benzodiazepines, opioids) as they may increase sedation.,Do not stop suddenly if taken regularly; taper dose to avoid withdrawal symptoms like headache or nausea.,Inform your doctor if you have glaucoma, urinary retention, or are taking MAO inhibitors (e.g., phenelzine, tranylcypromine).,Take exactly as prescribed; do not increase dose or frequency.,May cause dry mouth; use sugar-free gum or candy for relief.
No interactions on record
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about POVAN vs FLEXERIL, answered by our medical review team.
POVAN is a Anthelmintic that works by Pyrvinium pamoate inhibits oxidative metabolism and glucose uptake in susceptible helminths, leading to energy depletion and paralysis of the worm. It also binds to DNA and inhibits RNA synthesis in the parasite.. FLEXERIL is a Muscle Relaxant that works by Cyclobenzaprine is a centrally acting muscle relaxant that acts primarily at the brainstem, reducing tonic somatic motor activity via inhibition of descending serotonergic pathways. It is structurally related to tricyclic antidepressants and exhibits anticholinergic, sedative, and analgesic effects.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between POVAN and FLEXERIL depend on the specific clinical indication. These are agents from distinct pharmacological classes and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of POVAN is: Pyrantel pamoate: 11 mg/kg (maximum 1 g) orally once; repeat in 2 weeks for pinworm. For ascariasis, hookworm, trichostrongyliasis: 11 mg/kg (max 1 g) once daily for 3 days.. The standard adult dose of FLEXERIL is: 10 mg to 15 mg orally three times a day; maximum daily dose: 30 mg.. Dosing should always be individualized based on indication, renal and hepatic function, age, and other patient factors.
No direct drug-drug interaction has been formally documented between POVAN and FLEXERIL in current clinical databases. However, individual patient risk factors including other medications, organ function, and comorbidities should always be evaluated by a qualified healthcare provider.
The maternal-fetal safety profiles differ. POVAN is classified as Category C. Pyrvinium pamoate (Povan) is not recommended during pregnancy due to insufficient human data. Animal studies have not shown teratogenicity, but risk cannot be excluded. In first tr. FLEXERIL is classified as Category C. Pregnancy Category B. Animal studies have not demonstrated fetal risk, but no adequate human studies in pregnant women. Use only if clearly needed. First trimester: no known risk. . Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.