Tobacco Use Disorder

Tobacco Use Disorder - Puff Problems Primer

• Definition: A DSM-5 diagnosis; problematic pattern of tobacco use leading to clinically significant impairment or distress.
• Epidemiology: Major preventable cause of morbidity/mortality worldwide. High prevalence in India, especially smokeless tobacco. Initiation common in adolescence.
• Neurobiology:
  • Nicotine: Key psychoactive, addictive substance.
  • Receptors: Binds to nicotinic acetylcholine receptors (nAChRs), primarily $\alpha4\beta2$ subtype in the ventral tegmental area (VTA).
  • Mechanism: Stimulates dopamine release in mesolimbic pathway (nucleus accumbens), reinforcing use.

⭐ Varenicline, a partial agonist at $\alpha4\beta2$ nAChRs, is a first-line pharmacotherapy for smoking cessation, reducing cravings and withdrawal symptoms.

Tobacco Use Disorder - Cravings & Criteria

• Craving: Intense desire/urge for tobacco; key feature of withdrawal & relapse.
• DSM-5 Criteria (≥2 in 12 months):
  • Larger amounts/longer period than intended
  • Persistent desire/unsuccessful efforts to cut down/control
  • Much time spent obtaining/using/recovering
  • Craving, or a strong desire or urge to use
  • Recurrent use → failure to fulfill major role obligations
  • Continued use despite social/interpersonal problems
  • Important activities given up/reduced
  • Recurrent use in hazardous situations
  • Use continued despite knowledge of physical/psychological problem
  • Tolerance (need for ↑ amounts; ↓ effect with same amount)
  • Withdrawal (characteristic syndrome; substance taken to relieve/avoid)

⭐ Nicotine acts on nicotinic cholinergic receptors (nAChRs), especially α4β2, in the ventral tegmental area (VTA), leading to dopamine release in the nucleus accumbens, reinforcing its use.

Tobacco Use Disorder - Systemic Smoke Signals

• Cardiovascular: ↑Risk of Myocardial Infarction (MI), stroke, Peripheral Vascular Disease (PVD), hypertension. Strong association with Buerger's disease (thromboangiitis obliterans).
• Respiratory: Chronic Obstructive Pulmonary Disease (COPD) (emphysema, chronic bronchitis), lung cancer, asthma exacerbation, ↑pneumonia risk.
• Oncogenic: Major risk for multiple cancers: lung, oral cavity, larynx, esophagus, bladder, pancreas, kidney, cervix, acute myeloid leukemia.
• Gastrointestinal: Peptic ulcer disease, Gastroesophageal Reflux Disease (GERD).
• Reproductive & Perinatal: ↓Fertility, ectopic pregnancy, Intrauterine Growth Restriction (IUGR), preterm birth, stillbirth, ↑Sudden Infant Death Syndrome (SIDS) risk.
• Other Systems: Osteoporosis, type 2 diabetes mellitus, impaired wound healing, premature skin aging, periodontitis, ↑cataract risk, rheumatoid arthritis.

⭐ Tobacco smoke contains over 70 identified human carcinogens, significantly increasing the risk for a wide range of malignancies throughout the body.

Tobacco Use Disorder - Freedom Formulations

Pharmacotherapy Goal: Reduce withdrawal symptoms, prevent relapse. Always combine with behavioral support.

1. Nicotine Replacement Therapy (NRT)

• Delivers nicotine, reduces withdrawal from tobacco toxins.
• Forms & Key Dosing (typical):
  • Gum: 2mg (<25 cigs/day), 4mg (≥25 cigs/day). Max 24 pieces/day. "Chew & park" technique.
  • Patch: 21mg/14mg/7mg step-down regimen (8-12 weeks).
  • Lozenge: 1mg/2mg/4mg (dosed by time to first cigarette).
  • Inhaler: Mimics hand-to-mouth behavior.
  • Nasal Spray: Fastest NRT onset; highest dependence potential among NRTs.
• Common Side Effects: Local irritation (patch, spray), dyspepsia (gum, lozenge), hiccups.

2. Non-NRT Medications

• Bupropion SR (Sustained Release)
  • Atypical antidepressant (NDRI). Start 1-2 weeks before quit date.
  • Dose: 150mg OD for 3 days, then 150mg BD. Duration: 7-12 weeks.
  • Contraindications: Seizure disorder, current/prior bulimia or anorexia nervosa, MAOI use within 14 days.
• Varenicline
  • Partial agonist at α4β2 nicotinic acetylcholine receptors. Start 1 week before quit date.
  • Dose: Titrate from 0.5mg OD to 1mg BD. Duration: 12 weeks (can be extended).
  • Common Side Effects: Nausea (most common, take with food), insomnia, abnormal dreams.

  ⭐ Varenicline is generally considered the most effective single pharmacotherapy for smoking cessation.

3. Combination Therapy

• Often ↑ efficacy, especially for high nicotine dependence.
  • NRT Patch (long-acting) + Short-acting NRT (e.g., gum, lozenge).
  • Bupropion SR + NRT Patch.

Flowchart: Overview of Treatment Modalities

High‑Yield Points - ⚡ Biggest Takeaways

• Nicotine, acting on nicotinic acetylcholine receptors (nAChRs), is the primary addictive substance in tobacco.
• Withdrawal symptoms typically peak within 1-4 days and include irritability, anxiety, difficulty concentrating, and increased appetite.
• First-line pharmacotherapies include Varenicline, Bupropion, and Nicotine Replacement Therapy (NRT).
• Major long-term health consequences are COPD, lung cancer, and cardiovascular diseases.
• The Fagerström Test for Nicotine Dependence is a standard tool for assessing dependence severity.
• Smoking cessation counseling often utilizes the 5 A's model: Ask, Advise, Assess, Assist, Arrange.