The acute lethal doses of the hydrochloride and napsylate salts of propoxyphene were determined in 4 species. The results shown in Figure 2 indicate that on a molar basis, the napsylate salt is less toxic than the hydrochloride. This may be due to the relative insolubility and retarded absorption of propoxyphene napsylate.
|LD50 (mg/kg) ± SE|
|Mouse||282 ± 39||915 ± 163|
|Rat||230 ± 44||647 ± 95|
|Rabbit||ca. 82||> 183|
|Dog||ca. 100||> 183|
Some indication of the relative insolubility and retarded absorption of propoxyphene napsylate was obtained by measuring plasma propoxyphene levels in 2 groups of 4 dogs following oral administration of equimolar doses of the 2 salts. As shown in Figure 3, the peak plasma concentration observed with propoxyphene hydrochloride was much higher than that obtained after administration of the napsylate salt.
Figure 3. Plasma propoxyphene concentrations in dogs following large doses of the hydrochloride and napsylate salts.
Although none of the animals in this experiment died, 3 of the 4 dogs given propoxyphene hydrochloride exhibited convulsive seizures during the time interval corresponding to the peak plasma levels. The 4 animals receiving the napsylate salt were mildly ataxic but not acutely ill.
YOUR PRESCRIPTION FOR PROPOXYPHENE HYDROCHLORIDE AND ACETAMINOPHEN TABLETS
Products containing propoxyphene are used to relieve pain.
LIMIT YOUR INTAKE OF ALCOHOL WHILE TAKING THIS DRUG. Make sure your doctor knows if you are taking tranquilizers, sleep aids, antidepressants, antihistamines, or any other drugs that make you sleepy. Combining propoxyphene with alcohol or these drugs in excessive doses is dangerous.
Use care while driving a car or using machines until you see how the drug affects you, because propoxyphene can make you sleepy. Do not take more of the drug than your doctor prescribed. Dependence has occurred when patients have taken propoxyphene for a long period of time at doses greater than recommended.
The rest of this leaflet gives you more information about propoxyphene. Please read it and keep it for further use.
Uses for Propoxyphene
Products containing propoxyphene are used for the relief of mild to moderate pain. Products which contain propoxyphene plus acetaminophen are prescribed for the relief of pain or pain associated with fever.
Before taking Propoxyphene
Make sure your doctor knows if you have ever had an allergic reaction to propoxyphene or acetaminophen.
The effect of propoxyphene in children under 12 has not been studied. Therefore, use of the drug in this age group is not recommended.
How to take Propoxyphene
Follow your doctor’s directions exactly. Do not increase the amount you take without your doctor’s approval. If you miss a dose of the drug, do not take twice as much the next time.
Do not take propoxyphene during pregnancy unless your doctor knows you are pregnant and specifically recommends its use. Cases of temporary dependence in the newborn have occurred when the mother has taken propoxyphene consistently in the weeks before delivery. As a general principle, no drug should be taken during pregnancy unless it is clearly necessary.
Heavy use of alcohol with propoxyphene is hazardous and may lead to overdosage symptoms (see “Overdosage” below); THEREFORE, LIMIT YOUR INTAKE OF ALCOHOL WHILE TAKING PROPOXYPHENE.
Combinations of excessive doses of propoxyphene, alcohol, and tranquilizers are dangerous. Make sure your doctor knows if you are taking tranquilizers, sleep aids, antidepressant drugs, antihistamines, or any other drugs that make you sleepy. The use of these drugs with propoxyphene increases their sedative effects and may lead to overdosage symptoms, including death (see “Overdosage” below).
Propoxyphene may cause drowsiness or impair your mental and/or physical abilities; therefore, use caution when driving a vehicle or operating dangerous machinery. DO NOT perform any hazardous task until you have seen your response to this drug.
Propoxyphene may increase the concentration in the body of medications such as anticoagulants (“blood thinners”), antidepressants, or drugs used for epilepsy. The result may be excessive or adverse effects of these medications. Make sure your doctor knows if you are taking any of these medications.
You can become dependent on propoxyphene if you take it in higher than recommended doses over a long period of time. Dependence is a feeling of need for the drug and a feeling that you cannot perform normally without it.
An overdose of propoxyphene, alone or in combination with other drugs, including alcohol, may cause weakness, difficulty in breathing, confusion, anxiety, and more severe drowsiness and dizziness. Extreme overdosage may lead to unconsciousness and death.
If the propoxyphene product contains acetaminophen, the overdosage symptoms include nausea, vomiting, lack of appetite, and abdominal pain. Liver damage may occur even after symptoms disappear. Death can occur days later.
In any suspected overdosage situation, contact your doctor or nearest hospital emergency room. GET EMERGENCY HELP IMMEDIATELY.
KEEP THIS AND ALL DRUGS OUT OF THE REACH OF CHILDREN.
Possible Side Effects
When propoxyphene is taken as directed, side effects are infrequent. Among those reported are drowsiness, dizziness, nausea, and vomiting. If these effects occur, it may help if you lie down and rest.
Less frequently reported side effects are constipation, abdominal pain, skin rashes, light-headedness, headache, weakness, minor visual disturbances, and feelings of elation or discomfort.
If side effects occur and concern you, contact your doctor.
The safe and effective use of propoxyphene depends on your taking it exactly as directed. This drug has been prescribed specifically for you and your present condition. Do not give this drug to others who may have similar symptoms. Do not use it for any other reason.
If you would like more information about propoxyphene, ask your doctor or pharmacist. They have a more technical leaflet (professional labeling) you may read.
Watson Laboratories, Inc.
Corona, CA 92880 USA
Rev: September 2003
| PROPOXYPHENE HYDROCHLORIDE AND ACETAMINOPHEN |
propoxyphene hydrochloride and acetaminophen tablet
|Labeler — Watson Laboratories, Inc.|
Revised: 02/2007 Watson Laboratories, Inc.
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