Fentanyl is a synthetic opiate analgesic with a rapid onset and short duration of action. It is a strong agonistA substance that initiates a physiological response when combined with a receptor. at the μ-opioid receptors and is historically used to treat breakthrough pain. Fentanyl is approximately 100 times more potent than morphine, and is commonly used as a patch. The patches work by releasing fentanyl into body fats, which then slowly release the drug into the bloodstream over 48 to 72 hours, allowing for long-lasting relief from pain.

History

Fentanyl was first synthesized by Paul Janssen in 1960. Fentanyl was introduced in patch form in the mid 1990s, shortly followed by lollipop form. As of 2012 fentanyl was the most widely used synthetic opioid in clinical practice.

Dosage

Approximately 100 micrograms of fentanyl is equivalent to 10mg of morphine. Rate of absorption is dependent on a number of factors. Body temperature, skin type, amount of body fat, and placement of the patch can have major effects. Fentanyl is available as a patch, nasal spray, lollipop lozenge (brand name Actiq, or colloquially "percopop"), or inhaler.

Patch

BioavailabilityThe fraction of an administered dose that is absorbed into a living system.: varies per manufacturer; there is higher ba in the enclosed-satchel (such as Sandoz) vs the adhesive-matrix (such as Mylan) patches. The difficulty with ba in patches is separating the drug from the adhesive or carrier. It is difficult to extract a dose from either vehicle with sufficient accuracy to prevent harm in a recreational setting.

Comeup time: 20 to 60 minutes.

Duration: 24 to 72 hours; varies based upon ambient temperature, body temperature, skin salinity and perspiration, location of patch (volume of adipose tissue under the dermis), type of patch, dosage of patch. Most tolerant users will find 24 hours to be about the limit whereas naive users will more likely see 72 hours.

Medium (typical) dose: 50μg/hr + (depending on tolerance)

Patches are available in doses ranging from 12.5μg/hr to 100μg/hr, with patches previously available at strengths to 200μg/hr having been discontinued. Total fentanyl content of these patches are 1.25mg to 10mg; not all of this is available to the body from the patch and would have to be extracted using e.g., ethanol for "complete" usage.

The patch may be taken orallyRoute of administration in which the subject swallows a substance. (sublinguallyRoute of administration in which the subject places a substance under the tongue.) by sectioning into doses (such as 1/10th of a 10mg patch being 1mg delivered), but it is not recommended, and requires a solvent such as overproof ethanol for sufficient absorption.

Insufflated

Fentanyl powder may be snorted, but it is not recommended.

Smoked

The gel inside patches can be smoked. The powder also may be smoked, although it is not recommended.

Injected

Fentanyl is most commonly prepared in a saline solution with lactose or inositol as a buffering agent and either sold as heroin or as fentanyl itself. Fentanyl is not commonly available by itself as a powder and has low potential for abuse due to the low margin of safety with microgram-scale dosages.

Effects

The effects of fentanyl are similar to that of heroin.

Positive

  • Analgesia
  • Euphoria
  • Feelings of relaxation

Neutral

  • Sedative effects
  • Changes in focus, attention

Negative

  • Respiratory depression
  • Diarrhoea
  • Nausea
  • Constipation
  • Dry Mouth
  • Somnolence
  • Confusion
  • Weakness
  • Sweating
  • Headache
  • Fatigue
  • Dizziness
  • Nervousness
  • Anxiety
  • Urinary retention
  • Hallucinations

After effects

  • Risk of post-acute withdrawal effects, diarrhea including depression, anxiety disorder, psychosis, or even suicidal ideation in extreme cases

Harm Reduction

Fentanyl is considered one of the safest opioid medications on the market, as well as the least physically harmful to the body with long-term or life-term use. Still, fentanyl has caused overdoses and deaths, especially when mixed with other drugs.

Illicitly synthesized fentanyl powder has also appeared on the United States market. Because of the extremely high strength of pure fentanyl powder, it is very difficult to dilute appropriately, and often the resulting mixture may be far too strong and, consequently, very dangerous.

Sometimes fentanyl is sold as heroin. Some dealers may mix fentanyl powder with heroin to increase potency or compensate for low-quality heroin. If you have any concerns about your drug, please test it.

  • Avoid driving and operating heavy machinery
  • Risk of Post-acute withdrawal effects
  • Strong addiction potential due to short effects
  • Risk of overdose/death


Chemistry and Pharmacology

Fentanyl is a potent μ-opioid receptor agonistA substance that initiates a physiological response when combined with a receptor. with relatively little effect on κ or δ receptors compared to most opioids. Being very lipid soluble, it penetrates the blood-brain barrier quickly and efficiently, which accounts for its high potency compared to traditional opioids. When taken orallyRoute of administration in which the subject swallows a substance., fentanyl undergoes extensive first-pass metabolism by CYP3A4 to non-active metabolites, and as such, CYP3A4 inhibitors (such as grapefruit juice) could potentially be very dangerous when coadministered with fentanyl.

Images

various commercial preparations for parenteral administration
packaging for the 100ug/hr Mylan brand fentanyl patch
a 75ug/hr Mylan patch applied to the skin


Legal status

In most countries, fentanyl is illegal to sell without a license and illegal to buy or possess without a license or prescription.

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