Benperidol (Anquil, Frenactil): Why This Butyrophenone Is Not in U.S. Pharmacies and What Telehealth Can Still Do

Last updated: August 25, 2026

Benperidol (brands Anquil and Frenactil) is a high-potency first-generation butyrophenone antipsychotic. Janssen discovered it in 1961 and it has been marketed since 1966 in parts of Europe. U.S. retail pharmacies do not stock it. If you or a relative used Anquil abroad, a U.S. licensed clinician can still review symptoms, discuss FDA-available alternatives, and plan follow-up by video.

See conditions Klarity clinicians evaluate or learn how online anxiety and related mental health visits work.

TLDR

• Benperidol is a typical butyrophenone (ATC N05AD07) used mainly for schizophrenia and, in some European settings, hypersexuality syndromes. See DrugBank DB12867 and NCATS Inxight UNII 97O6X78C53.
• Identifiers: CAS 2062-84-2, PubChem CID 16363, formula C22H24FN3O2, molar mass about 381.45, codes R-4584 / McN-JR-4584 / NSC-170982. Half-life is often listed around 8 hours; a 6 mg PK study reported oral half-lives near 4.7-5.5 hours.
• It is among the most potent European neuroleptics by chlorpromazine-equivalent tables (about 75-100, roughly 150-200% the dose potency of haloperidol). It is mainly used in Germany and also listed in Belgium, Greece, the Netherlands, and the United Kingdom (Wikipedia summary).
• Cochrane (Leucht and Hartung, CD003083) found only one small, poorly reported RCT (Eckmann 1984: 6 or 12 mg/day vs perphenazine). Evidence for schizophrenia is very weak (PMC7017029).
• U.S. patients cannot fill Anquil here. Telehealth can still evaluate psychosis, anxiety, and related symptoms and discuss medicines U.S. pharmacies actually stock. Coverage varies by plan; verify benefits before you book.

What people ask about benperidol

• What is benperidol (Anquil, Frenactil)?
• Is Anquil available in the United States?
• How have clinicians dosed benperidol?
• What does research say?
• What side effects and warnings matter?
• What can U.S. telehealth still do?
• FAQ

What is benperidol (Anquil, Frenactil)?

Benperidol is a butyrophenone with a benzimidazolinone-piperidine side chain, chemically close to droperidol and pimozide’s precursor family. Clinical summaries describe it as a strong D2 (and D4) antagonist with weaker 5-HT2A antagonism and little anticholinergic activity. NCATS notes antiemetic potential via the chemoreceptor trigger zone and weak muscarinic, H1, and alpha-1 effects.

Trade names include Anquil and Frenactil. Development codes include R-4584. It sits in WHO-ATC class N05AD07 with other butyrophenones such as haloperidol and droperidol. That class grouping does not mean U.S. pharmacies can substitute Anquil for Haldol.

European use has two historical threads. One is ordinary schizophrenia care. The other is older forensic or “hypersexuality” prescribing, sometimes as a parole condition instead of anti-androgens. Those uses are jurisdiction-specific and are not a U.S. standard of care. A U.S. visit should start from current symptoms, safety, and FDA-available options, not from importing a European forensic protocol.

Is Anquil available in the United States?

NCATS Inxight lists marketing as “Possibly Marketed Outside US,” with an unknown U.S. approval year. There is no everyday U.S. brand on pharmacy shelves. People search “benperidol” and “Anquil” after a move from Germany or the UK, after seeing a relative’s European discharge list, or after reading older forensic literature.

The practical U.S. answer is substitution with an FDA-available oral or long-acting antipsychotic, not an Anquil transfer. Do not import unlabeled tablets. A clinician licensed in your state should redesign the plan.

Browse condition pages if you need a starting point for what a visit can cover.

How have clinicians dosed benperidol?

These figures are historical European or trial doses. They are not a U.S. prescribing guide.

The only RCT Cochrane accepted used 6 or 12 mg/day (a few patients received 9 mg on selected days) versus perphenazine 12 or 24 mg/day in 40 hospitalized adults with acute paranoid schizophrenia (Eckmann 1984 via Cochrane). NCATS also records a 6 mg single oral and IV pharmacokinetic study (Cmax about 10 ng/mL oral vs 105 ng/mL IV) and an older sample oral range of 0.003 to 0.01 mg/kg every 12 hours. Wikipedia lists an elimination half-life of about 8 hours and extensive first-pass metabolism, with about 1% excreted unchanged in urine.

Potency tables that call benperidol “more potent than haloperidol” refer to milligram-for-milligram D2 blockade, not to better outcomes. High potency usually means more extrapyramidal risk at modest milligram counts.

What does research say?

Cochrane CD003083 (Leucht and Hartung; last methodological update 2009) searched for randomized trials of benperidol in schizophrenia. After decades of European use they found one unpublished, inadequately reported trial. Randomization, allocation concealment, and early dropouts were unclear. The authors judged the evidence very poor and said better reporting would have made the review far more useful. Later update searches did not add included studies.

That gap is the clinical takeaway. A famous European name is not the same as a strong evidence base. U.S. guidelines lean on antipsychotics with larger modern trials and FDA labels.

What side effects and warnings matter?

As a high-potency D2 blocker, benperidol carries the usual first-generation risks: acute dystonia, parkinsonism, akathisia, tardive dyskinesia, hyperprolactinemia, and neuroleptic malignant syndrome. NCATS also flags extrapyramidal effects and tardive dyskinesia. High-dose use can add antihistaminic and alpha-adrenergic effects (sedation, orthostasis).

Class phenothiazine/butyrophenone liver-injury discussions live on LiverTox NBK548610. Older forensic papers discussed endocrine and sexual-function changes; those are not reasons to start the drug in the U.S.

If you feel suicidal or are in crisis, call or text 988 in the United States. For a medical emergency, call 911.

What can U.S. telehealth still do?

Klarity’s network includes 2,000+ licensed clinicians. A video visit can review your history (including overseas Anquil use), screen for psychosis, anxiety, and depression, and discuss FDA-available medicines and therapy. It cannot create a U.S. Anquil supply.

HHS notes that recent legislation extended many Medicare telehealth flexibilities through December 31, 2027, including home-originating sites for behavioral health and a pause on the six-month in-person requirement for Medicare behavioral telehealth through that date (Telehealth.HHS.gov, last updated February 5, 2026). Commercial coverage still varies by plan. Verify benefits before you book.

See how online mental health visits work or start from a condition page.

FAQ

Is benperidol the same as haloperidol?

No. Both are butyrophenones. Benperidol is a different molecule (benzimidazolinone side chain) and is not stocked as a U.S. retail product the way generic haloperidol is.

Can I keep taking leftover Anquil after I move to the United States?

Do not self-continue a foreign antipsychotic without a U.S.-licensed clinician. Bring the original packaging to a visit so the clinician can map the dose to an available alternative.

Does insurance cover a visit to discuss this?

Many plans may cover telehealth mental health evaluation. Coverage varies by plan and state. Confirm benefits before you book. This page is educational and is not a guarantee of coverage or a prescription.

Disclaimer

This article is for education. It is not medical advice, a diagnosis, or a promise that any medicine or visit is covered. Prescription decisions belong to a licensed clinician who evaluates you. Insurance coverage varies by plan; verify benefits before booking.