Clinical data | |
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AHFS/Drugs.com | International Drug Names |
Routes of administration | Oral |
ATC code | |
Pharmacokinetic data | |
Bioavailability | Dose Dependent |
Metabolism | Saturable Hepatic |
Elimination half-life | Dose Dependent |
Identifiers | |
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CAS Number | |
PubChem CID | |
DrugBank | |
ChemSpider | |
UNII | |
KEGG | |
ChEBI | |
ChEMBL | |
CompTox Dashboard (EPA) | |
ECHA InfoCard | 100.026.881 |
Chemical and physical data | |
Formula | C19H35N |
Molar mass | 277.496 g·mol−1 |
3D model (JSmol) | |
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Perhexiline (Pexsig) is a prophylactic antianginal agent used primarily in Australia and New Zealand. Perhexiline is thought to act by inhibiting mitochondrial carnitine palmitoyltransferase-1. This shifts myocardial metabolism from fatty acid to glucose utilisation which results in increased ATP production for the same O2 consumption and consequently increases myocardial efficiency. Its clinical use has been limited by its narrow therapeutic index and high inter- and intra-individual pharmacokinetic variability. It was outlawed in many countries due to its adverse effects on poor metabolisers (PM). The product has been reintroduced for patients who have contraindications, or have not responded to other treatments for angina.
The major route of perhexiline metabolism in humans is hydroxylation by microsomal CYP2D6. [1] The two main metabolites of perhexiline are the cis and trans isomers of hydroxyperhexiline. [1] CYP2D6 accounts for only a small percentage of total hepatic CYP450s but it is one of the main pathways for phase one metabolism of xenobiotics. [2] The limited availability of CYP2D6 means perhexiline metabolism is a saturable process. [3]
It is estimated that 7–10% of Caucasians are CYP2D6 poor metabolisers (PMs). [4] Most PMs have an autosomal recessive polymorphism in the CYP2D6 locus which results in the severely compromised metabolism of at least 25 drugs. [5] It is believed that there are hundreds of potential polymorphism which will result in a PM, some result in functionally deficient CYP2D6, while others cause the absence of CYP2D6. [6] [7]
Cis-hydroxyperhexiline is the primary determinant of perhexiline clearance and there is relatively little interindividual variability in the clearance of Cis-hydroxyperhexiline; [8] therefore, the Cis-hydroxyperhexiline/perhexiline concentration ratio may be useful for optimizing individual patient treatment with the antianginal agent perhexiline. [8] There is a segment of the population with very low hydroxyperhexiline/perhexiline ratios, this subpopulation contains those patients with the PM phenotype. [8] It has been suggested that those with ratios ≤0.3 should be considered PMs; thus, providing a simple method for identifying PMs.
The adverse effects of perhexiline have been seen in more than 60% of recipients in some clinical trials. The most commonly reported adverse effects include headache, dizziness, nausea and vomiting. Plasma perhexiline concentrations as low as 0.6mg/L> are known to cause nausea and dizziness; however, perhexiline is also known to cause hepatotoxicity and peripheral neuropathy at plasma concentrations >0.6mg/L. [9] [10] The symptoms of peripheral neuropathy include weakness or sensory loss and pain in the arms, hand, legs, and feet. Histological investigations indicate the development of phospholipoidosis, with scaly inclusions in hepatocytes, Schwann cells and other tissues which could point to the cause of peripheral neuropathy. [11] The peripheral neuropathy is often but not always permanent. [10] The risk of perhexiline toxicity is reduced by therapeutic drug monitoring (TDM). [12]
The simplest way to rectify the problem of perhexiline toxicity is to stop administering the drug and allowing the plasma concentration to fall; [9] once the concentration has reached the desired level resume the treatment at a lower dose. Most PMs should receive doses of no more than 50mg/week of perhexiline. [8]
Hydrocodone, also known as dihydrocodeinone, is a semisynthetic opioid used to treat pain and as a cough suppressant. It is taken by mouth. Typically it is dispensed as the combination acetaminophen/hydrocodone or ibuprofen/hydrocodone for pain severe enough to require an opioid and in combination with homatropine methylbromide to relieve cough. It is also available by itself in a long-acting form under the brand name Zohydro ER, among others, to treat severe pain of a prolonged duration. Hydrocodone is a controlled drug: in the United States a Schedule II Controlled Substance.
Tramadol, sold under the brand name Ultram among others, is an opioid pain medication and a serotonin–norepinephrine reuptake inhibitor (SNRI) used to treat moderately severe pain. When taken by mouth in an immediate-release formulation, the onset of pain relief usually begins within an hour. It is also available by injection. It is available in combination with paracetamol (acetaminophen).
Clonidine, sold under the brand name Catapres among others, is an α2A-adrenergic agonist medication used to treat high blood pressure, ADHD, drug withdrawal, menopausal flushing, diarrhea, spasticity, and certain pain conditions. The drug is often prescribed off-label for tics. It is used orally, by injection, or as a transdermal skin patch. Onset of action is typically within an hour with the effects on blood pressure lasting for up to eight hours.
Amitriptyline, sold under the brand name Elavil among others, is a tricyclic antidepressant primarily used to treat major depressive disorder, a variety of pain syndromes such as neuropathic pain, fibromyalgia, migraine and tension headaches. Due to the frequency and prominence of side effects, amitriptyline is generally considered a second-line therapy for these indications.
Atomoxetine, sold under the brand name Strattera, is a medication used to treat attention deficit hyperactivity disorder (ADHD) and, to a lesser extent, cognitive disengagement syndrome. It may be used alone or along with psychostimulants. It is also used as a cognitive and executive functioning enhancer to improve self-motivation, persistence, attention, inhibition, and working memory. Use of atomoxetine is only recommended for those who are at least six years old. It is taken orally. Atomoxetine is a selective norepinephrine reuptake inhibitor and is believed to work by increasing norepinephrine and dopamine levels in the brain. The effectiveness of atomoxetine is comparable to the commonly prescribed stimulant medication methylphenidate.
Cimetidine, sold under the brand name Tagamet among others, is a histamine H2 receptor antagonist that inhibits stomach acid production. It is mainly used in the treatment of heartburn and peptic ulcers.
Cytochrome P450 3A4 is an important enzyme in the body, mainly found in the liver and in the intestine, which in humans is encoded by CYP3A4 gene. It oxidizes small foreign organic molecules (xenobiotics), such as toxins or drugs, so that they can be removed from the body. It is highly homologous to CYP3A5, another important CYP3A enzyme.
Cytochrome P450 2D6 (CYP2D6) is an enzyme that in humans is encoded by the CYP2D6 gene. CYP2D6 is primarily expressed in the liver. It is also highly expressed in areas of the central nervous system, including the substantia nigra.
In pharmaceutical sciences, drug interactions occur when a drug's mechanism of action is affected by the concomitant administration of substances such as foods, beverages, or other drugs. A popular example of drug-food interaction is the effect of grapefruit in the metabolism of drugs.
Nortriptyline, sold under the brand name Pamelor, among others, is a medication used to treat depression. This medicine is also sometimes used for neuropathic pain, attention deficit hyperactivity disorder (ADHD), smoking cessation and anxiety. As with many antidepressants, its use for young people with depression and other psychiatric disorders may be limited due to increased suicidality in the 18–24 population initiating treatment. Nortriptyline is a less preferred treatment for ADHD and stopping smoking. It is taken by mouth.
Doxepin is a medication belonging to the tricyclic antidepressant (TCA) class of drugs used to treat major depressive disorder, anxiety disorders, chronic hives, and insomnia. For hives it is a less preferred alternative to antihistamines. It has a mild to moderate benefit for sleeping problems. It is used as a cream for itchiness due to atopic dermatitis or lichen simplex chronicus.
Dextromethorphan (DXM) is a cough suppressant used in many cough and cold medicines. It affects serotonin, norepinephrine, NMDA, and sigma-1 receptors in the brain, all of which have been implicated in the pathophysiology of depression. In 2022, the FDA approved the combination dextromethorphan/bupropion to serve as a rapid acting antidepressant in patients with major depressive disorder.
Some fruit juices and fruits can interact with numerous drugs, in many cases causing adverse effects. The effect is most studied with grapefruit and grapefruit juice, but similar effects have been observed with certain other citrus fruits.
Cytochrome P450 family 2 subfamily C member 9 is an enzyme protein. The enzyme is involved in the metabolism, by oxidation, of both xenobiotics, including drugs, and endogenous compounds, including fatty acids. In humans, the protein is encoded by the CYP2C9 gene. The gene is highly polymorphic, which affects the efficiency of the metabolism by the enzyme.
Cytochrome P450 2C19 is an enzyme protein. It is a member of the CYP2C subfamily of the cytochrome P450 mixed-function oxidase system. This subfamily includes enzymes that catalyze metabolism of xenobiotics, including some proton pump inhibitors and antiepileptic drugs. In humans, it is the CYP2C19 gene that encodes the CYP2C19 protein. CYP2C19 is a liver enzyme that acts on at least 10% of drugs in current clinical use, most notably the antiplatelet treatment clopidogrel (Plavix), drugs that treat pain associated with ulcers, such as omeprazole, antiseizure drugs such as mephenytoin, the antimalarial proguanil, and the anxiolytic diazepam.
Lisdexamfetamine, sold under the brand names Vyvanse and Elvanse among others, is a stimulant medication that is used to treat attention deficit hyperactivity disorder (ADHD) in children and adults and for moderate-to-severe binge eating disorder in adults. Lisdexamfetamine is taken by mouth. Its effects generally begin within two hours and last for up to 14 hours. In the United Kingdom, it is usually less preferred to methylphenidate for the treatment of children.
Tapentadol, brand names Nucynta among others, is a centrally acting opioid analgesic of the benzenoid class with a dual mode of action as an agonist of the μ-opioid receptor and as a norepinephrine reuptake inhibitor (NRI). Analgesia occurs within 32 minutes of oral administration, and lasts for 4–6 hours.
Deramciclane (EGIS-3886) is a non-benzodiazepine-type anxiolytic drug to treat various types of anxiety disorders. Deramciclane is a unique alternative to current anxiolytics on the market because it has a novel chemical structure and target. It acts as an antagonist at the 5-HT2A receptor, as an inverse agonist at the 5-HT2C receptor, and as a GABA reuptake inhibitor. The two serotonin receptors are G protein-coupled receptors and are two of the main excitatory serotonin receptor types. Their excitation has been implicated in anxiety and mood. Deramciclane does not affect CYP3A4 activity in metabolizing other drugs, but it is a weak inhibitor of CYP2D6. Some studies also show the drug to have moderate affinity to dopamine D2 receptors and low affinity to dopamine receptor D1. Researchers are looking for alternatives to benzodiazepines for anxiolytic use because benzodiazepine drugs have sedative and muscle relaxant side effects.
Nordoxepin, also known as N-desmethyldoxepin, is an organic compound. A colorless solid, it attracted attention as the major active metabolite of the tricyclic antidepressant (TCA) doxepin (Sinequan). It has been found to play a significant role in the antidepressant effects of doxepin.
Selective norepinephrine reuptake inhibitors (sNRIs) are a class of drugs that have been marketed as antidepressants and are used for various mental disorders, mainly depression and attention-deficit hyperactivity disorder (ADHD). The norepinephrine transporter (NET) serves as the fundamental mechanism for the inactivation of noradrenergic signaling because of the NET termination in the reuptake of norepinephrine (NE). The selectivity and mechanism of action for the NRI drugs remain mostly unresolved and, to date, only a limited number of NRI-selective inhibitors are available. The first commercially available selective NRI was the drug reboxetine (Edronax), developed as a first-line therapy for major depressive disorder. Atomoxetine (Strattera) is another potent and selective NRI which is also effective and well tolerated for the treatment of ADHD in adults; it may also be a new treatment option for adults with ADHD, particularly for those patients at risk of substance abuse.