Penthrox Methoxyflurane Green Whistle in Dentistry

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Penthrox Methoxyflurane Green Whistle in Dentistry

Pain has been a true associate of mankind for ages and is also, unfortunately, a result of most of dental procedures and surgeries; hence quality control of dental pain is inevitable. The administration of local anesthesia has become the standard of care in dentistry. Various kinds of local anesthesia are currently being used in the dental profession, depending upon the duration of the surgical procedure, the patient’s medical history, and the pharmacological interaction between the patient’s regular medications and the local anesthesia being administered. All local anesthesia shall be effective, along with a high safety parameter.

Anesthesia is the absence of sensation in a circumscribed area of the body caused by inhibiting nerve conduction in peripheral nerves or by depressing excitation in nerve endings. An important feature of local anesthesia is that it produces a loss of sensation without producing a loss of consciousness.

Surgical removal of third molar teeth is the most common procedure in oral surgery. Many patients who are about to undergo surgical third molar removal experience high levels of preoperative anxiety. This fear and anxiety can deter some patients from consulting or delaying consultation so that the eventual treatment becomes more urgent and often more difficult for the dentist because of anxiety-related patient behavior during the intervention. This fear can be overcome during treatment with oral or inhalational sedation in the dental chair.


Penthrox methoxyflurane was introduced as an inhalational anesthetic agent in the mid-1960s. The Penthrox inhaler produces a colorless, fruity liquid after the liquid is poured into it. It is found to have an idiosyncratic potential to cause effective non-narcotic analgesia and relief of anxiety at low levels.

What is Penthrox Methoxyflurane Inhaler?Penthrox Methoxyflurane Inhaler

The Penthrox inhaler is a hand-held simple green plastic device 15 cm long with a mouthpiece at one end and a wick running through the center. It is often referred to as the ‘Green Whistle.’ The active substance used in anthrax inhalers is Methoxyflurane. Each sealed bottle contains 3 ml methoxyflurane (99.9%) and Butylated hydroxytoluene (0.1%).

How to Use The Penthrox Inhaler?How to Use The Penthrox Inhaler

The 3 ml bottle of methoxyflurane is poured onto the wick. The inhaler is then shaken to eliminate any excess liquid, and the mouthpiece is wiped properly. The maximum dose of Penthrox methoxyflurane administered through the Penthrox inhaler shall not be more than 6 ml of methoxyflurane i.e., 2 bottles. The inhaler delivers 0.1-0.2% of methoxyflurane with the dilator hole uncovered and 0.2-0.4% with the dilator hole covered during inhalation. Initially, two very shallow puffs shall be administered to make the patient accustomed to the strong fruity smell.

What is Penthrox Used For?

Penthrox methoxyflurane has been actively used as a first-line analgesic agent to reduce pain and relieve anxiety in various clinical settings. Clinical research has revealed that methoxyflurane has mood-elevating properties that help in improving dental conditions during dental operative procedures.

It is ideal for office-based dental sedation because of the ease of administration and disseminates the need for nasal masks and tedious analgesic equipment. It can also be considered an additional simple treatment option for patients requiring rapid non-injectable, non-narcotic sedation in dental practice.

Advantages of Penthrox MethoxyfluraneAdvantages of Penthrox Methoxyflurane

Inhalational sedation has unique advantages. Its onset of action is rapid, and the effect can be maintained for as long as the administration lasts. The depth of sedation can be titrated and adjusted because the drug is eliminated through the airway. Instead of a peak effect, a plateau can be reached within a few minutes, and recovery from the state of sedation occurs within minutes of ceasing administration.

Penthrox is a potent non-narcotic inhalation that has a rapid onset and a gradual offset. It is intended to reduce pain and anxiety rather than eliminate it. It is safe to be used by adults and children young enough to breathe in/out from the inhaler. The sensation obtained post-usage is that of “feel-good relaxation.”

Possible Adverse Reactions Associated With Its Use

Despite its good safety record in analgesic doses, adverse reactions have been recorded.

Some of the serious side effects of the Penthrox inhaler are:

  • Serious allergic reactions, including difficulty in breathing and swelling of the face
  • Liver problems such as loss of appetite, nausea, vomiting, jaundice, dark-colored urine, pale-colored stools, and sensitive right stomach area.
  • Kidney problems like reduced or excessive urination and swelling of feet or lower legs.
  • Dizziness or drowsiness
  • Low or high blood pressure

Common Side Effects of The Inhaler Include:

  • Dry mouth
  • Headache, anxiety or depression
  • Disturbance in attention
  • Inappropriate emotions or actions
  • Tingling sensations in hand and feet
  • Flushing of the skin
  • Double vision


Adverse effects are rare when methoxyflurane is administered in analgesic doses. However, its legitimate role and limitations in dental surgery are unclear. There is a lack of recent, well-designed studies describing or supporting its use in routine dental practice. Practitioners, at a minimum, must be aware of the risks of this drug to their patients, their staff, and themselves. Current regulations for the use of inhalational sedatives used in dentistry call for formalized training of the practitioner and the requirement of appropriate surgery and ventilation design. These regulations should be applied to the use of methoxyflurane.


Author Since:  September 18, 2018


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