Treatment methods having reduced drug-related toxicity and methods of identifying the likelihood of patient harm from prescribed medications
Methods of determining whether specific drugs or patients carry an increased risk of causing or developing, respectively, long QT syndrome or Torsades de Pointes and methods of treating such patients.
1 . A method of treating patients having an increased risk of developing long QT syndrome or Torsades de Pointes due to a patient-specific score exceeding a predetermined threshold value, the method comprising:
one or more steps of (a)-(h):
(a) determining a risk variable having a value between 0 and 0.5 based on the patient's gender and age;
(b) determining a risk variable having a value between 0 and 1 based on a measurement of the patient's heart rhythm, the measurement comprising detecting one or more of sinus rhythm, atrial fibrillation, sick sinus syndrome, pause, and heart rate;
(c) determining a risk variable having a value between 0 and 1 based on a detected potassium level in the patient;
(d) determining a risk variable having a value between 0 and 1 based on a detected magnesium level in the patient;
(e) determining a risk variable having a value between 0 and 1 based on a detected presence of one or more diuretics in the patient;
(f) determining a risk variable having a value between 0 and 9 based on a detected presence of one or more antiarrhythmics in the patient;
(g) determining a risk variable having a value between 0 and 12 based on calculating a drug-specific index for the one or more drugs in the patient's treatment regimen, including the patient's use of QT-prolonging drugs and/or a presence of drug-drug interactions, by:
calculating a first index variable for the drug by determining:
an IC 50 value for block of one or more of I Kr and I Ks for the drug,
a Cmax of the drug at a test dose,
a daily dose amount of the drug,
a protein binding value for the drug at a target protein, and
a drug-drug interaction coefficient (DDIC) for the drug;
calculating a second index variable for the drug by determining:
an IC 50 value for block of CaV1.2 current for the drug, and
the IC 50 value for block of one or more of I Kr and I Ks for the drug;
calculating a third index variable for the drug by determining:
an IC 50 value for block of NaV1.5 current for the drug, and
the IC 50 value for block of one or more of I Kr and I Ks for the drug;
calculating a fourth index variable for the drug based on whether the drug is an inhibitor of hERG trafficking; and
combining the first, second, third, and fourth index variables to provide the drug-specific index, which is indicative of the drug's risk of causing long QT syndrome or Torsades de Pointes,
wherein the drug is selected from the group consisting of Albuterol, Alfuzosin, Amantadine, Amiodarone, Amitriptyline, Amphetamine, Arsenic trioxide, Astemizole, Atazanavir, Atomoxetine, Azithromycin, Bepridil, Chloral hydrate, Chloroquine, Chlorpromazine, Ciprofloxacin, Cisapride, Citalopram, Clarithromycin, Clomipramine, Clozapine, Cocaine, Desipramine, Dexmethylphenidate, Diphenhydramine, Diphenhydramine, Disopyramide, Dobutamine, Dofetilide, Dolasetron, Domperidone, Dopamine, Doxepin, Dronedarone, Droperidol, Ephedrine, Epinephrine, Erythromycin, Escitalopram, Escitalopram, Famotidine, Felbamate, Fenfluramine, Flecamide, Fluconazole, Fluoxetine, Foscarnet, Fosphenyloin, Galantamine, Gatifloxacin, Gemifloxacin, Granisetron, Halofantrine, Haloperidol, Ibutilide, Imipramine, Indapamide, Isoproterenol, Isoproterenol, Isradipine, Itraconazole, Ketoconazole, Lapatinib, Lapatinib, Levalbuterol, Levofloxacin, Levomethadyl, Lisdexamfetamine, Lithium, Mesoridazine, Metaproterenol, Methadone, Methylphenidate, Midodrine, Moexipril/HCTZ, Moxifloxacin, Nicardipine, Nilotinib, Norepinephrine, Nortriptyline, Octreotide, Ofloxacin, Ondansetron, Oxytocin, Paliperidone, Paroxetine, Pentamidine, Perflutren lipid microspheres, Phentermine, Phenylephrine, Phenylpropanolamine, Pimozide, Probucol, Procainamide, Protriptyline, Pseudoephedrine, Quetiapine, Quinidine, Ranolazine, Risperidone, Ritodrine, Ritonavir, Roxithromycin, Salmeterol, Sertindole, Sertraline, Sibutramine, Solifenacin, Sotalol, Sparfloxacin, Sunitinib, Tacrolimus, Tamoxifen, Telithromycin, Terbutaline, Terfenadine, Thioridazine, Tizanidine, Tolterodine, Trazodone, Trimethoprim-Sulfa, Trimipramine, Vandetanib, Vardenafil, Venlafaxine, Voriconazole, Ziprasidone, and a pharmaceutically acceptable salt thereof; and
(h) determining a risk variable having a value between 0 and 10 based on the patient's QT interval;
the method further comprising combining the determined risk variables from the one or more of steps (a)-(g) to obtain a patient-specific score, wherein a patient-specific score exceeding a predetermined threshold value is indicative that the patient has an increased risk of long QT syndrome or Torsades de Pointes;
and administering a therapeutically effective amount of a medication to decrease the patient's risk of developing long QT syndrome or Torsades de Pointes if the patient-specific score exceeds the predetermined threshold.
2 . The method of claim 1 , wherein the medication is a potassium salt.
3 . The method of claim 1 , wherein the medication is a magnesium salt.
4 . The method of claim 1 , further comprising treating a patient with the drug, wherein the drug is determined to increase the risk of long QT syndrome or Torsades de Pointes as a result of the drug's drug-specific index, the method comprising the steps of:
administering a pharmaceutical composition to the patient comprising a therapeutically effective amount of the drug or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier;
determining whether the patient has an increased risk of developing long QT syndrome or Torsades de Pointes due to a patient-specific score that is indicative of an increased risk of developing long QT syndrome or Torsades de Pointes; and
halting treatment of the patient with the pharmaceutical composition upon determination that the patient has an increased risk of developing long QT syndrome or Torsades de Pointes based on the patient-specific score calculated to include the drug's drug-specific index.
5 . The method of claim 4 , further comprising the step of administering an additional pharmaceutical composition to the patient that does not include the drug.
6 . The method of claim 5 , wherein the additional pharmaceutical composition comprises an additional drug that has a drug-specific index at or below a predetermined drug-specific index threshold value.
7 . The method of claim 5 , wherein the additional pharmaceutical composition comprises a LQTS medicament configured to treat Long QT Syndrome and/or Torsades de Pointes.
8 . The method of claim 2 , wherein the potassium salt comprises potassium chloride.
9 . The method of claim 3 , wherein the magnesium salt comprises magnesium sulfate.
10 . The method of claim 1 , wherein the predetermined threshold value is 10.