September 2015 PHARMACOLOGY OF ADDICTIONS - PowerPoint Presentation

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September 2015

PHARMACOLOGY OF ADDICTIONS

Understanding the pharmacological basis of medications used to manage dependenceUnderstanding how pharmacological agents are used to treat dependence

Understanding that different medications are needed in the different phases of addictionDescribing the medications commonly prescribed in dependenceLEARNING OUTCOMES

Substance dependence encompasses physical and psychological problemsPhysical dependence: on cessation of a drug to which the body has become adjusted, withdrawal symptoms occur. This can be life-threatening

Psychological dependence: emotional and mental preoccupation with substances and craving CONTEXT

Treat emergencies: overdose, seizures, dehydration, hypothermia/hyperthermia, acute confusional

state, delirium tremensTreat detoxification and withdrawal syndromes: diazepam, chlordiazepoxide, lofexidine, methadone, buprenorphineSubstitution: methadone, buprenorphine, nicotine replacement therapy, bupropionRelapse prevention: naltrexone, acamprosate, disulfiram

Treatment of vitamin deficiencyTreatment of comorbid psychiatric and physical disorders PHARMACOLOGICAL INTERVENTIONS

Patients should have the opportunity to make informed decisions about their care in partnership with professionalsSpecial groups will need their treatment managed appropriately

eg older and younger people will need lower doses and account needs to be taken of comorbid illnesses in older peoplePsychosocial interventions must be part of the package A full detailed assessment, including blood, urine, saliva investigations to ensure that substances have been used, has to be made before decisions about pharmacological treatment can be madeObservations of withdrawal should be elicited if possible

SPECIAL ISSUES

Antagonists at post synaptic receptor ie block synaptic transmission

eg naltrexone Agonists have strong or 100% action on the receptor eg methadonePartial agonists induce less effect ie less than 100% eg buprenorphine Partial agonists will act like an antagonist if there is a full agonist present

TYPES OF MEDICATIONS

Methadone: long acting, half life 24 hours, can be used once a day

Can be reduced slowly over weeks, has less euphoria than heroin Side effects: lethargy, respiratory depression at high doses especially with alcohol and benzodiazepines, constipation, reduced saliva (contributing to poor dental hygiene)Buprenorphine: partial agonist, long half life, administered once dailyAttenuates the effects of opiatesProduces less sedation, less euphoria and positive reinforcement, less respiratory depression

DRUGS USED IN OPIATE DEPENDENCE

Naltrexone: used when patient is abstinent; blocks the effects of heroin or opiate agonists and prevents reinforcing effects.

Naloxone is a short acting opiate antagonist used in emergencies Lofexidine: adjunctive medication which reduces withdrawal symptomsAdjunctive medication i.e. anti inflammatory, anti-emetics, anti- depressants should only be prescribed at the lowest effective dosage, when clinically indicated ie

when specific symptoms are present, and risk interactions should be considered

Benzodiazepines: Reduce symptoms of withdrawalReduce occurrence of delirium tremens

Reduce seizuresDRUGS USED IN ALCOHOL DEPENDENCE

Disulfiram: used when patient is abstinent.Acts by inhibition of acetaldehyde dehydrogenase with leads to accumulation of acetaldehyde which interacts with alcohol to produce nausea, vomiting, headache, flushing, palpitations and hypotension, which can lead to collapse and death

Acamprosate: commences once patient is abstinent and can improve rates of abstinence. It is hypothesised to reduce craving and urge to drinkNaltrexone: better than placebo at reducing risk of lapse

NicotineNicotine gum or patches, bupropion,

varenicline E-cigarettesStimulantNo agents have been found to be useful Cannabis: No pharmacological agents have been shown to be helpful, but MET, CBT, CM have shown benefits

DRUGS USED IN NICOTINE, STIMULANT AND CANNABIS DEPENDENCE

Rarely present with dependenceRarely require substitute medicationMost pharmacological preparations are not licensed for adolescents

Initiation should be offered by a specialist addiction psychiatrists or specially qualified doctorsSometimes they require symptomatic medicationNon-pharmacological interventions should be part of the treatment whether pharmacological treatments are being administeredSPECIAL POPULATIONS – YOUNG PEOPLE

Require dosage reduction and careful monitoringNeeds to take account of comorbid mental and physical health problems e.g. neuropsychiatric disorders, hepatic and respiratory complications

Need to take account of other medications prescribed and the interactions with medications for substance use disordersShould be undertaken with the expertise of professionals trained in geriatric medicine, addiction psychiatry, old age psychiatryInitiation of detoxification and reduction regimes should be undertaken by the advice of specialists in addictionParticular caution should be taken with acamprosate, disulfiram, naltrexone

SPECIAL POPULATIONS – OLDER PEOPLE

Pharmacological treatment is one part of an integrated coordinated treatment planA range of professional staff are involved in providing different components

Coordination is necessary so that patients do not seek medication from different GPs, doctors and hospitalsPharmacists should be included in the multidisciplinary team to discuss issues e.g. choice of treatment, initi ation of medication, dosing regime, interactions with other medications

NETWORKS, REFERRAL AND SERVICES

Crome I.B (2009) Substance misuse and addiction in adolescence – issues

for the practising GP in Care of Children and young people for the MRCGP (ed K.Mohanna). London. Royal College of General

Practitioners.Department of Health (2007) Drug misuse and dependence – guidelines on clinical management: http://www.nta.nhs.uk/guidelines.aspxLingford-Hughes, A. R., Welch, S., Peters, L and Nutt, D. J., with expert reviewers Ball

, D., Buntwal, N., Chick, J., Crome, I. B., et al. BAP updated guidelines: evidence based guidelines for the pharmacological management of substance abuse, harmful use, addiction and comorbidity: recommendations from

BAP (2012)

Journal of Psychopharmacology

1-54 http

://jop.sagepub.com/content/26/7/899

Findings (2014) Authoritative review reveals limitations of

medicatingdependence

http

://

findings.org.uk/count/downloads/download.php?file=Lingford_Hughes_AR_2.txt.

References

Luty. J., (2015) Drug and alcohol addiction: new pharmacotherapies.

B J Prych Advances (21), 33-41 doi: 10.1192/apt.bp.114.013367NICE (2007)

Drug Misuse: naltrexone for the management of opioid dependence (NICE technology appraisal,TA115) http://www.nice.org.uk/guidance/TA115NICE (2007) Drug misuse: methadone and buprenorphine maintenance (NICE technology

appraisal, TA114) http://www.nice.org.uk/guidance/TA114NICE (2007) Drug misuse: opioid detoxification (NICE clinical guideline, CG52)

http

://

www.nice.org.uk/CG52

NICE (2007)

Drug misuse: psychosocial interventions (NICE clinical

guideline, CG51

)

http://

www.nice.org.uk/CG51

NICE (2010)

Alcohol-use disorders: physical complications (NICE clinical

guideline, CG100

)

http://

guidance.nice.org.uk/CG100

NICE

(2011)

Alcohol use disorders: diagnosis, assessment and management

of harmful

drinking and alcohol dependence (NICE clinical guideline,

CG115)

http

://

guidance.nice.org.uk/CG115

Royal College of Psychiatrists (2011)

Our invisible addicts First Report of

the Older

Persons’ Substance Misuse

Working Group of the Royal College

of Psychiatrists

.

http://

www.rcpsych.ac.uk/files/pdfversion/cr165.pdf

References

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