There is always an overabundance of Propoxyphene related questions on BL. Here are some very basic facts about this drug.
The most common prescription Propoxyphene products contain the Napsylate salt. Darvon-N, Darvocet, etc contain Propoxyphene Napsylate.
It is rare, but Propoxyphene Hydrochloride is still available.
The difference between them is Propoxyphene Napsylate is not water soluble. It is also 'weaker' than Propoxyphene Hydrochloride (100mg P. Napsylate = 65mg P. Hydrochloride).
In the old days, to prevent people from crushing and injecting Darvon, the salt was changed to the non-water soluble Napsylate.
Never do a CWE on Darvocet
It is pointless.
The maximum daily dose of Propoxyphene Napsylate is 600mg. With the highest dose Darvocet tablets, it means 6 tablets. Six of these highest dose Darvocet is 3900 APAP/Acetaminophen, 600mg Propoxyphene Napsylate.
So, not only is Propoxyphene Napsylate not water soluble, you will take too much Propoxyphene before you took too much APAP/Tylenol with Darvocet.
Propoxyphene, in any salt form, is toxic in high doses. This is why the maximum recommended daily dosage is 600mg throughout the day. After this point you run the risk of toxicity damaging the heart (the main metabolite of Propoxyphene is Norpropoxyphene, which is a potent local anaesthetic, 10x as potent as Lidocaine; these drugs are very hard on the heart).
Propoxyphene also has uncomfortable side effects, even at low or therapeutic dosages. Confusion, disorientation, 'clumsiness', 'mental fog', rigid movement, etc.
It does produce euphoria and typical mu agonist effects (miosis, constipation, sedation, etc).
While people often bad mouth Darvon, in many situations it is a very useful drug. In a medical setting, it is a 'weak' opioid. However, it is an excellent first-line analgesic for low to moderate pain. While the analgesia it provides is equal to a large dose of an NSAID, it is a very good palliative therapy. Meaning, the euphoria, warmth and sedation it provides is very helpful to people suffering from low to moderate pain.
The long half-life of the main metabolite, Norpropoxyphene, makes Propoxyphene a very good choice for maintenance or as a reduction/taper aid. In the early to mid 1960s, around the time Methadone maintenance was beginning to spread, Propoxyphene was a commonly used opioid for a reduction/taper treatment inpatient and outpatient (many doctors still prescribe it for this purpose today).
So, to review:
-No more than 600mg a day
-Toxic at high doses
-More than one salt are on the market, though the most common is the Napsylate salt
-The HCL salt is more potent by weight than the Napsylate salt: 100mg Napsylate = 65mg HCL