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A number of questions have been raised about heroin and methadone blockers and their use for treatment for drug dependency, including alcohol and opiates, particularly among those who oppose its use. Questions have concerned the legality of use, side-effects and drug interactions, its effectiveness, safety issues, especially during detoxification procedures and overdose among heroin users. Many of these questions are addressed in detail in the book "The Use of Naltrexone in the Treatment of Opiate Dependence". The following presents an overview of the types of questions asked and provides some answers. These antagonist medications are originally used for treatment of alcohol dependency. Hazardous alcohol consumption is a widespread problem effecting 20% of the Australian population. It is estimated that 9.4% of males and 6.5% of females are considered to be dependent drinkers and are at risk of alcohol related health problems and the other associated risks, such as assault, falls and drownings, caar accidents, child abuse and accidents and injury (Goldman, 1996). It has been found in research studies to decrease craving (Volpicelli, Alterman, Hayasghida and O'Brien, 1992, in Revia Product Guide, 2003); O'Malley, Jaffe, Rhode and Rousaville, 1996, in Revia Product Guide, 2003; O'Malley, et al., 1992, in Revia Product Guide, 2003) , increase abstinence (O'Malley, et al., 1992; Anton, Moak, Waid, Latham, Malcolm and Dias 1999, in Revia Product Guide, 2003), risk of relapse (Volpicelli, et al., 1992, in Revia Product Guide, 2003; O'Malley, et al., 1992; Anton, Moak, Waid, Latham, Malcolm and Dias 1999, in Revia Product Guide, 2003; Volpicelli, Alterman, Rhimes, Rhimes, Volpicelli and O'Brien, 1997, in Revia Product Guide, 2003), no significant side-effects (Volpicelli, et al., 1992, in Revia Product Guide, 2003), no significant drug interactions, other than opiates (Volpicelli, et al., 1992, in Revia Product Guide, 2003), is not associated with mood swings (Volpicelli, et al., 1992, in Revia Product Guide, 2003), it is non-addictive and does not accumulate.

While the drug has been heavily promoted by drug and alcohol treatment providers and policy makers for alcohol dependency, questions have been raised about the use of antgonist to precipitate withdrawal and the use Heroin and Methadone blocking implants and their approval for human use. Until trials are completed and the implants are registered by the Therapeutic Goods Administration, 'not for human use' is a standard warning of which prospective patients should be made aware. Heroin and Methadone blocking implants are used under the Special Access Scheme and therefore has TGA approval on the basis opiate dependence is a life threatening condition. This novel approach has been designed to overcome compliance problems experienced by some patients. While death rates continue to fall, when heroin was plentiful and cheap overdose deaths rose to nearly 1000 per annum. Many people die each year from drug overdose where methadone is a factor.

Under the TGA's Special Access Scheme, doctors are free to prescribe any medication for a use for which it is not registered, use a new unregistered medication or, in this case, a new device for application of a registered drug, where a patient's life is considered at risk. This is no different to how doctors use new therapies in the treatment of diseases such as, HIV/AIDS, diabetes, cancer and heart disease. Prior to TGA approval of antagonist medication in January 1999, the drug was widely used for both detoxification and maintenance of abstinence from heroin and methadone, under provisions of the TGA Act, the Special Access Scheme. A small group of doctors are now using this provision of the Act to insert Heroin and Methadone blocking implants.

Questions have also been raised about Heroin and Methadone blocking implants and clinical trials. Clinical trials have been conducted in the United Kingdom specifically on Heroin and Methadone blocking medication implants ("Naltrexone implants completely prevent early (one month) relapse after opiate detoxification" Foster and Brewer,1999). The latest trial results from around the world were presented at the 6 th International Conference on Pharmacotherapy (11-12 April 2011).

We have conducted a study over one year comparing oral naltrexone to implant naltrexone involving 84 patients. The results are published in an International peer-reviewed medical journal. Outcomes showed that 80% of patients using a three month implant were opiate free at 6 months (Colquhoun, R. M, Tan, D. Y. K. and Hull , S. (2005), "A comparison of oral and implant naltrexone outcomes at 12 months". Journal of Opioid Management, Dec, 2005).

Heroin and Methadone blocking implants employ the same release technology as those used in other implants for contraception, impotence and menopause. The materials that carry the active component and control release rates have been widely tested over many years.

Critics of Heroin and Methadone blocking medication are often concerned about the success rates with naltrexone. Studies show high success rates for people who are highly motivated by threats to their careers or who have been mandated by courts and who receive comprehensive counselling and psychosocial support and this is acknowledged in the literature. However, researchers have been very cautious about the efficacy of using the medication among less motivated groups of heroin or methadone users. Prof. John Saunders estimates that only 10% of these groups would be suitable (Wodak, Saunders, Mattick, and Hall, 2001).

Advocates, as well as critics of Heroin and Methadone blocking medication, agree that patients need to be selected for suitability, however, studies have often used 'street addicts', who have little desire to be abstinent, as trial subjects ( Bell, Young, Masterman, Morris, Mattick, and Bammer, 1999). The same studies have also neglected to provide the necessary support counselling and to ensure some compliance regime is in place. Not surprisingly, these studies show poor outcomes and yet the well-known answers to these problems, which lead to good outcomes, are often not implemented.

The trend toward implants is an attempt to make compliance much simpler and to solve these problems which critics of Heroin and Methadone blocking medication have raised. It is important to recognise that Heroin and Methadone blocking medication is not suitable for all patients and that there is a role for other treatment strategies.

Safety issues are of concern to health authorities and clients and it is often asked if implants can be overpowered with life-threatening doses of heroin or methadone. The selection of patients is an important component in any program and patients need to undergo thorough psychological testing and to give free and informed consent to having an implant inserted (Colquhoun, 1998). It is unlikely patients are able to overpower implants unless the use of the drug is accompanied by large doses of alcohol or other sedative medication. High suicide rates have been documented among this patient group and while every attempt should be made to support these patients, or to direct them to alternative treatments, some will want to end their lives (Miotto, McCann, Rawson, Frosch, & Ling, 1997). In other words, patients are specifically warned about attempting to over-ride the effect of Naltrexone, and to use the quantity of heroin to over-ride the Naltrexone is clearly a deliberate attempt to harm themselves.

Following from this question comes the suggestion that there is an increased risk of infection. With any minor surgery such as, the implant procedure, there is some risk of infection and this should be treated appropriately.