HALFAN HAS BEEN SHOWN TO PROLONG QTc INTERVAL AT THE RECOMMENDED THERAPEUTIC DOSE. THERE HAVE BEEN RARE REPORTS OF SERIOUS VENTRICULAR DYSRHYTHMIAS SOMETIMES ASSOCIATED WITH DEATH, WHICH MAY BE SUDDEN. HALFAN IS THEREFORE NOT RECOMMENDED FOR USE IN COMBINATION WITH DRUGS OR CLINICAL CONDITIONS KNOWN TO PROLONG QTc INTERVAL, OR IN PATIENTS WHO HAVE PREVIOUSLY RECEIVED MEFLOQUINE, OR IN PATIENTS WITH KNOWN OR SUSPECTED VENTRICULAR DYSRHYTHMIAS, A-V CONDUCTION DISORDERS OR UNEXPLAINED SYNCOPAL ATTACKS. HALFAN SHOULD BE PRESCRIBED ONLY BY PHYSICIANS WHO HAVE SPECIAL COMPETENCE IN THE DIAGNOSIS AND TREATMENT OF MALARIA, AND WHO ARE EXPERIENCED IN THE USE OF ANTIMALARIAL DRUGS. PHYSICIANS SHOULD THOROUGHLY FAMILIARIZE THEMSELVES WITH THE COMPLETE CONTENTS OF THIS LEAFLET BEFORE PRESCRIBING HALFAN.
HALFAN (halofantrine hydrochloride) is an antimalarial drug available as tablets containing 250 mg of halofantrine hydrochloride (equivalent to 233 mg of the free base) for oral administration. The chemical name of halofantrine hydrochloride is 1,3-dichloro-α-[2-(dibutylamino) ethyl]-6-(trifluoromethyl)-9-phenanthrene-methanol hydrochloride. The drug, a white to off-white crystalline compound, is practically insoluble in water.
HALFAN tablets are indicated for the treatment of adults who can tolerate oral medication and who have mild to moderate malaria (equal to or less than 100,000 parasites/mm3) caused by Plasmodium falciparum or Plasmodium vivax.
NOTE: Patients with acute P. vivax malaria treated with HALFAN are at risk of relapse because halofantrine does not eliminate the exoerythrocytic (hepatic phase) parasites. To avoid relapse after initial treatment of the acute P. vivax infection with HALFAN, patients should subsequently be treated with an 8-aminoquinoline to eradicate the exoerythrocytic parasites.
NOTE: THE EFFICACY OF HALFAN IN THE PROPHYLAXIS OF MALARIA HAS NOT BEEN ESTABLISHED.
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Published Studies Related to Halfan (Halofantrine)
Effect of fluconazole on the pharmacokinetics of halofantrine in healthy volunteers. [2009.12]
BACKGROUND: Halofantrine, an antimalarial drug used in endemic areas such as the tropics is mainly metabolized by CYP3A4 to the active metabolite N-desbutylhalofantrine. Fluconazole, an antifungal agent and an inhibitor of CYP3A4 is an established part of the therapy in HIV patients, who in turn are prone to malaria in the tropics. This study investigated the effect of fluconazole on the pharmacokinetics of halofantrine after concurrent administration of the two drugs... CONCLUSION: The decreased plasma concentrations of the metabolite are presumably caused by metabolic inhibition of CYP3A4 by fluconazole. Although the therapeutic consequences of this interaction are not clear caution should be exercised when co-administering both drugs to avoid accumulation and subsequent cardiotoxic effects of halofantrine.
Effects of prior administration of amodiaquine on the disposition of halofantrine in healthy volunteers. [2007.04]
The prevalence of multidrug-resistant malaria parasites brings about the switch from an antimalarial drug with poor therapeutic outcome to an effective alternative, resulting in overlap in the plasma drug levels. In this study, the influence of prior administration of amodiaquine on the pharmacokinetics and electrocardiographic effect of halofantrine (HF) was investigated in healthy volunteers...
Effect of experimental hyperlipidaemia on the electrocardiographic effects of repeated doses of halofantrine in rats. [2010.11]
BACKGROUND AND PURPOSE: Halofantrine can cause a prolongation of the cardiac QT interval, leading to serious ventricular arrhythmias...
In vitro susceptibility of Plasmodium falciparum to monodesethylamodiaquine, quinine, mefloquine and halofantrine in Abidjan (Cote d'Ivoire). [2010.06]
BACKGROUND: Malaria is the primary cause of hospitalization in Cote d'Ivoire. Early treatment is one of the strategies to control this illness. However, the spread of resistance of Plasmodium falciparum to antimalarial drugs can seriously compromise this strategy. OBJECTIVES: The aim of this study was to assess the in vitro susceptibility of P. falciparum to monodesethylamodiaquine and aminoalcohols in Abidjan (Cote d'Ivoire)... CONCLUSIONS: Our results showed that the in vitro chloroquine resistance reported in previous studies has been extended to other antimalarial drugs investigated in this study except for quinine. Therefore, it is necessary to implement a long-term monitoring system of antimalarial drug resistance.
Effects of polysorbate 80 on the in-vitro precipitation and oral bioavailability of halofantrine from polyethylene glycol 400 formulations in rats. [2010.01]
OBJECTIVES: The aim of this study was to examine the effects of formulations of polysorbate 80 (PS 80) and polyethylene glycol 400 (PEG 400) on the precipitation and oral bioavailability of the hydrophobic drug halofantrine... CONCLUSIONS: Addition of PS80 to the formulation increased the bioavailability of halofantrine and the more compound, the more PS80 was needed to prevent precipitation.
Clinical Trials Related to Halfan (Halofantrine)
Drug Interaction Study Between Lumefantrine and Lopinavir/Ritonavir [Recruiting]
With the roll out of antiretroviral therapy (ARV) for HIV across sub-Saharan Africa an
unprecedented number of people will be commencing lifelong therapy. Current estimates are
that 5-6 million people in sub-Saharan Africa require ART. At the same time, the World
Health Organization (WHO) Roll Back Malaria campaign is aggressively promoting the use of
artemether/lumefantrine as first-line therapy for malaria in this setting. Many patients in
this setting have already become resistant to first-line ARV and have moved onto
lopinavir/ritonavir (Kaletra) based second-line regimens. Kaletra is a potent inhibitor of
Cytochrome P450 3A4 (CYP 3A4), an enzyme responsible for the metabolism of many drugs which
is found predominantly in the liver and the gut. Lumefantrine, and to a lesser extent
artemether, is extensively metabolized by CYP 3A4. Therefore when given to a patient already
taking Kaletra for HIV, it is likely that elevated levels of these drugs in the patient will
result. There is some concern that lumefantrine may be cardiotoxic due to its structural
similarity to halofantrine which is known to cause irregular heart rhythms. This has not
been borne out as yet in any studies performed with lumefantrine, however it is not known
what levels will be achieved in patients when it is administered with a protease inhibitor
such as Kaletra. The WHO has not addressed this issue in any of its previous policy
documents but has identified ARV-antimalarial drug interaction studies as a research
priority. This single dose pharmacokinetic (PK) study aims to compare the levels of
lumefantrine/artemether that result when it is given to a patient on Kaletra with patients
not on any ARV. Data generated by this study will help address this important knowledge gap
which has been identified by WHO and others as meriting urgent investigation.