What drugs are used? Are there different types of IV sedation?

The most commonly used drugs for IV sedation are benzodiazepines, or "benzos" for short. These are anti-anxiety sedative drugs. In the NZ, a benzodiazepine is almost always the only drug used for IV sedation (although fentanyl may be used in conjuction).

Mostly the drug used for IV sedation is a short acting benzodiazepine, or "benzo" for short. This is an anti-anxiety sedative - see the Oral Sedation page for more info on benzos in general. IV administered benzos have 3 main effects: they reduce anxiety/relax you, they make you sleepy, and they produce partial or total amnesia (i.e. make you forget what happened during some or, less frequently, all of the procedure). Total amnesia is more common with midazolam compared to diazepam (see below). By far the most commonly used drug for IV sedation is Midazolam (tradenames: Hypnovel or Dormicum in NZ), but occasionally Diazepam (tradename: Valium) can be used.

Midazolam is the first choice because of its relatively short duration of action (meaning that it'll be out of your system faster). Valium is (marginally) cheaper but longer acting and a bit "harder" on the veins, so you may feel a burning sensation on your arm/hand when the drug first enters.

The drug is put into the vein at the rate of 1mg per minute for Diazepam or 1 mg every 2 minutes (followed by an extra 2 minutes to evaluate the effect) for Midazolam (because Midazolam is stronger in terms of the dose needed to achieve sedation). Because there are differences between individuals in how much of the drug you need to be sedated, your response to the drug is monitored. Once the desired level of sedation is achieved, the drug is stopped. It is then added at a slow rate over the period of your appointment to keep you at the desired level of sedation.

The Venflon is left in place during the procedure so that the sedation can either be topped up or so that the reversal agent for benzos (Flumazenil) can be put in, in the unlikely event of an emergency.

Barbiturates (sleep-inducing drugs) are not used for conscious sedation in the NZ. The only barbiturate which is still occasionally used is called Pentobarbital Sodium (tradename: Nembutal).

In the absence of a trained anesthetist, barbiturates are pretty dangerous to use.

Opioids like fentanyl (strong pain-killers) can be used as an add-on to either benzos (for procedures up to about 1.5 hours) or barbiturates (for procedures longer than 2 hours).

At first glance, the use of opioids seems appealing, because of the pain-killing factor. In reality, this usually only comes into play for post-treatment pain, because local anesthesia will take care of any pain during treatment. However, should the local anesthetic effect begin to lessen, an opioid will help to alter the experience of pain.

However, what is often done instead is give a long-acting local anesthetic where postop pain is expected. When you take opioids, even excruciating pain becomes tolerable - you can still feel the pain, but somehow you don't care (I've tried it!).

The addition of an opioid may also be desirable if a benzo has been administered to its maximal recommended dose yet the patient remains unsedated (which is more likely if you've been hitting the valium hard for years). In this case, adding an opioid may provide the desired sedation. Alternatively, propofol (see below) may be used.

Meperidine (Demerol)
Morphine
Butorphanol (Stadol)
Nalbuphine (Nubain)
Fentanyl (Sublimaze)
Pentazocine (Talwin)

Some anesthetists/dentists use Propofol instead of benzos. The advantage of this is the very rapid recovery time, less than 5 minutes. The disadvantage is the drug must be continuously administered, so the drug is pumped in using an electric infusion pump, the dose rate is set by the anesthetist. Propofol is not a common sedative agent because it's very easy to tip over into GA with it (where reflexes such as breathing are lost). It can be useful if a person is "immune" to benzos because they've been hitting them hard for years.

There are quite a few other drugs that CAN be used for IV sedation. But in practical terms, most of the time a single benzo, usually midazolam, is used. This is especially true in the NZ.
In the US, the situation is slightly more complex. Polydrug use appears to be much more common, possibly because IV sedation is taught at a high level. This encourages the use of polypharmacy (multiple drugs).

The general consensus among the leading experts in the field of dental sedation today is: the fewer medications are used, the safer the treatment tends to be (and the easier it is to track any potential problems). Usually, this means one medication only. Midazolam tends to be the drug of choice.