"Nov. 2, 2012 -- Safety steps taken in the wake of the fungal meningitis outbreak have worsened drug shortages, raising questions about whether the U.S. must choose between the safety and the availability of crucial medicines.
(Generic versions may still be available.)
In hospitalized patients, the most frequently reported were dizziness, sedation, nausea, and vomiting. Other adverse reactions include constipation, abdominal pain, skin rashes, lightheadedness, headache, weakness, euphoria, dysphoria, hallucinations, and minor visual disturbances.
The most frequently reported postmarketing adverse events have included completed suicide, accidental and intentional overdose, drug dependence, cardiac arrest, coma, drug ineffective, drug toxicity, nausea, respiratory arrest, cardio-respiratory arrest, death, vomiting, dizziness, convulsion, confusional state, and diarrhea.
Additional adverse experiences reported through postmarketing surveillance include:
Eye disorder: eye swelling, vision blurred
General disorder and administration site conditions: , drug interaction, drug tolerance, drug withdrawal syndrome
Gastrointestinal disorder: gastrointestinal bleed, acute pancreatitis
Hepatobiliary disorder: hepatic steatosis, hepatomegaly, hepatocellular injury
Immune system disorder: hypersensitivity
Injury poisoning and procedural complications: drug toxicity, hip fracture, multiple drug overdose, narcotic overdose
Metabolism and nutrition disorder: metabolic acidosis
Psychiatric: abnormal behavior, confusional state, hallucinations, mental status change
Respiratory, thoracic, and mediastinal disorders: respiratory depression, dyspnoea
Skin and subcutaneous tissue disorder: rash, itch
Liver dysfunction has been reported in association with Darvon. Propoxyphene therapy has been associated with abnormal liver function tests and, more rarely, with instances of reversible jaundice (including cholestatic jaundice).
Subacute painful myopathy has been reported following chronic propoxyphene overdosage.
Drug Abuse And Dependence
Darvon (propoxyphene) is a Schedule IV narcotic under the U.S. Controlled Substances Act. Darvon (propoxyphene) can produce drug dependence of the morphine type, and therefore, has the potential for being abused. Psychic dependence, physical dependence and tolerance may develop upon repeated administration. Darvon (propoxyphene) should be prescribed and administered with the same degree of caution appropriate to the use of other narcotic-containing medications.
Since Darvon (propoxyphene) is a mu-opioid agonist, it may be subject to misuse, abuse, and addiction. Addiction to opioids prescribed for pain management has not been estimated. However, requests for opioids from opioid-addicted patients occur. As such, physicians should take appropriate care in prescribing Darvon (propoxyphene) .
Opioid analgesics may cause psychological and physical dependence. Physical dependence results in withdrawal symptoms in patients who abruptly discontinue the drug after long term administration. Also, symptoms of withdrawal may be precipitated through the administration of drugs with mu-opioid antagonist activity, e.g., naloxone or mixed agonist/antagonist analgesics (pentazocine, butorphanol, nalbuphine, dezocine) (see OVERDOSAGE). Physical dependence usually does not occur to a clinically significant degree, until after several weeks of continued opioid usage. Tolerance, in which increasingly larger doses are required to produce the same degree of analgesia, is initially manifested by a shortened duration of an analgesic effect and subsequently, by decreases in the intensity of analgesia.
In chronic pain patients, and in opioid-tolerant cancer patients, the administration of Darvon (propoxyphene) should be guided by the degree of tolerance manifested and the doses needed to adequately relieve pain.
The severity of the Darvon (propoxyphene) abstinence syndrome may depend on the degree of physical dependence. Withdrawal is characterized by rhinitis, myalgia, abdominal cramping, and occasional diarrhea. Most observable symptoms disappear in 5 to 14 days without treatment; however, there may be a phase of secondary or chronic abstinence which may last for 2 to 6 months characterized by insomnia, irritability, and muscular aches. The patient may be detoxified by gradual reduction of the dose. Gastrointestinal disturbances or dehydration should be treated with supportive care.
Read the Darvon (propoxyphene) Side Effects Center for a complete guide to possible side effects
Drug Interactions with Propoxyphene
Propoxyphene is metabolized mainly via the human cytochrome P450 3A4 isoenzyme system (CYP3A4), therefore potential interactions may occur when propoxyphene is administered concurrently with agents that affect CYP3A4 activity.
The metabolism of propoxyphene may be altered by strong CYP3A4 inhibitors (such as ritonavir, ketoconazole, itraconazole, troleandomycin, clarithromycin, nelfinavir, nefazadone, amiodarone, amprenavir, aprepitant, diltiazem, erythromycin, fluconazole, fosamprenavir, grapefruit juice, and verapamil) leading to enhanced propoxyphene plasma levels. Coadministration with agents that induce CYP3A4 activity may reduce the efficacy of propoxyphene. Strong CYP3A4 inducers such as rifampin may lead to enhanced metabolite (norpropoxyphene) levels.
Propoxyphene is also thought to possess CYP3A4 and CYP2D6 enzyme inhibiting properties and coadministration with drugs that rely on either of these enzymes for metabolism may result in increased pharmacologic or adverse effects of that drug. Severe neurologic signs, including coma, have occurred with concurrent use of carbamazepine (metabolized by CYP3A4).
Increased risk of bleeding has been observed with warfarin-like agents when given along with propoxyphene; however, the mechanistic basis of this interaction is unknown.
Patients receiving narcotic analgesics, general anesthetics, phenothiazines, other tranquilizers, sedative-hypnotics or other CNS depressants (including alcohol) concomitantly with propoxyphene may exhibit an additive CNS depression. Interactive effects resulting in respiratory depression, hypotension, profound sedation, or coma may result if these drugs are taken in combination with the usual dosage of Darvon (propoxyphene) . When such combined therapy is contemplated, the dose of one or both agents should be reduced.
Mixed Agonist/Antagonist Opioid Analgesics
Agonist/antagonist analgesics (i.e., pentazocine, nalbuphine, butorphanol and buprenorphine) should be administered with caution to patients who have received or are receiving a course of therapy with a pure opioid agonist analgesic such as Darvon (propoxyphene) . In this situation, mixed agonist/antagonist analgesics may reduce the analgesic effect of Darvon (propoxyphene) and/or may precipitate withdrawal symptoms in these patients.
Monoamine Oxidase Inhibitors (MAOIs)
MAOIs have been reported to intensify the effects of at least one opioid drug causing anxiety, confusion and significant depression of respiration or coma. The use of Darvon (propoxyphene) is not recommended for patients taking MAOIs or within 14 days of stopping such treatment.This monograph has been modified to include the generic and brand name in many instances.
Last reviewed on RxList: 10/12/2009
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