[Pharmacokinetic interactions between methadone and antiretroviral medication in HIV positive patients]

Integrated opioid use disorder and HIV treatment: rationale, clinical guidelines for addiction treatment, and review of interactions of antiretroviral agents and opioid agonist therapies

Injection drug use (IDU) is an important vector of HIV infection in the United States. Many patients with HIV infection have comorbid substance use disorders. Integrated treatment for HIV and substance use disorders has been shown to improve HIV and other health outcomes, but significant barriers to integrated treatment exist. For individuals who are dependent on injection opioid drugs, agonist therapies of methadone or buprenorphine maintenance are available as part of a treatment program. Patients who are infected with HIV and require antiretroviral therapy (ART) are at risk for drug-drug interaction between ART and methadone or buprenorphine. We present a programmatic approach to the evaluation and treatment of opioid use disorders for HIV care providers, as well as a summary of the available knowledge of interactions of methadone and buprenorphine with ART, along with the level of evidence for each actual or potential interaction. Based on the available information of practice and the level of clinical significance of drug-drug interactions, we conclude that buprenorphine-based maintenance treatment for opioid dependent patients is the preferred maintenance therapy for integrated treatment systems.

Interacciones clínicas y farmacocinéticas entre metadona y nelfinavir (estudio Nemesia)

BACKGROUND AND OBJECTIVE

Patients on methadone maintenance therapy who are administered nelfinavir show a decrease in methadone plasma levels. However, the clinical relevance of this fact is seldom significant because it does not correlate with the appearance of opioid withdrawal symptoms (OWS). The objective of this study was to assess the clinical and pharmacokinetic interactions between methadone and nelfinavir.

PATIENTS AND METHOD

A prospective multicenter study of human immunodeficiency virus (HIV) positive patients on stable methadone therapy who initiated nelfinavir was performed. To determine the presence of OWS, 2 questionnaires, objective and subjective, were administered at weeks 1, 2, 3 and 4. A pharmacokinetic study measuring the minimal plasmatic concentration of methadone was done at baseline and at week 4.

RESULTS

29 patient were included. In 7 patients who underwent pharmacokinetic studies, the minimal plasmatic concentration of methadone decreased after 4 weeks of nelfinavir treatment from 6.889 ng/ml to 4.354 ng/ml (37%; p = 0.046). However the results of the questionnaires did not show the significant OWS, which precluded an increase in the dose of methadone.

CONCLUSIONS

In patients under stable methadone treatment, antiretroviral therapy including nelfinavir does not require any significant modification of methadone dose. The decrease in methadone plasmatic levels does not correlate with OWS.

[Evaluation of drug addicts with associated pathology. Clinical and therapeutic aspects of the integral attention]

We review the evaluation and treatment of patients with drug addictions complicated by other acute or chronic diseases from the perspective of the hospital setting. The spectrum of drug addiction's complications is broad and in many instances it is predetermined by the abuse substance and its administration route. Some complications of intravenous drug addiction have dramatically decreased in the last few years as a result of a better knowledge of hygienic customs and after the implementation of some health interventions such as the provision of sterile injectable devices. Two highly prevalent infections --HIV/AIDS and hepatitis C-- remain from the period in which most HIV infections owed to the intravenous use of heroin. Of note, these two infections largely account for the survival and quality of life of those who quit their addiction. On the other hand, it is still common the hospitalization of patients with both alcohol dependence and intercurrent diseases in whom their drug addiction may pass unnoticed. Other common situations include the treatment of acute patients with cocaine addiction and psychiatric comorbidity, patients under methadone therapy and, in general, all those cases in which, in emergency, ordinary hospital wards and specialized units, a wide differential diagnosis is raised when there is a coexistence of signs and symptoms common to an addiction, infection and/or intoxication. An integral vision of drug addiction and its complications, as well as the clinical evaluation of all health problems, is fundamental for the prognosis and treatment of these patients.

[Emergencies in patients attender in a drug abuse treatment center]

BACKGROUND AND OBJECTIVE

To find out the type of emergency consultations made by users at a substance abuse treatment center (SATC).

PATIENTS AND METHOD

Prospective study of emergency consultations made during six months by patients controlled at a SATC.

RESULTS

333 patients were followed up; 27 (8%) of them consulted and 9 (33%) were found to have an HIV infection. Heroin addicts consulted more times and repeated visits more commonly than cocaine addicts (p < 0.04 and 0.03). Patients enrolled in the methadone maintenance programme consulted less commonly than patients included in other programmes (p < 0.01). 35% of visited patients did not need treatment and 75% were discharged.

CONCLUSIONS

We have detected two different types of consultations: those owing to a psychiatric/drug disorder in patients followed-up for less than 1 year, which are resolved after just one visit, without need of hospitalization; and those consultations caused by medical disorders, frequently related to HIV, which are generated by patients submitted to longer follow-up periods; these patients use to repeat the consultations and are commonly admitted.