Accutane (Isotretinoin) and Nicotine: Full Interaction Profile

Is nicotine listed as an isotretinoin interaction?

No. The Absorica LD prescribing information says to avoid vitamin A supplements and to avoid tetracyclines, because isotretinoin has been associated with intracranial hypertension (pseudotumor cerebri) [1]. It also reports that isotretinoin did not cause clinically significant changes in the pharmacokinetics of norethindrone and ethinyl estradiol given as an oral contraceptive, and says it is not known whether other oral contraceptives interact [1]. The older Accutane-format label covers vitamin A and tetracyclines too, and adds micro-dosed progestin minipills, St. John's wort, phenytoin and systemic corticosteroids [2]. Nicotine, cigarettes and vaping do not appear in the interaction sections of either label.

The contraindications are equally narrow: pregnancy, and hypersensitivity to isotretinoin, vitamin A or any component [1]. Smoking status is not among them.

iPLEDGE, the restricted program that controls access, exists because of embryo-fetal toxicity [1]. Its listed requirements cover prescriber and pharmacy certification, pregnancy testing, counseling, comprehension checks, a 7-day prescription window for patients who can get pregnant, and, for patients who cannot get pregnant, enrollment plus no sharing of the drug and no blood donation [1]. None of those requirements concerns tobacco.

Do smoking and nicotine change how isotretinoin is broken down?

Isotretinoin is more than 99.9% bound to plasma proteins and has an elimination half-life of about 21 hours under both fed and fasted conditions. In-vitro work identifies CYP2C8, CYP2C9, CYP3A4 and CYP2B6 as the primary isoforms involved in its metabolism [2].

Cigarette smoke induces a different set of enzymes. Polycyclic aromatic hydrocarbons in smoke are believed to be responsible for induction of CYP1A1 and CYP1A2, and possibly CYP2E1 [4][5]. Nicotine itself is metabolized mainly by CYP2A6 [6][7]. A review of drugs affected by quitting says the smoking effect on liver enzymes is not related to the nicotine component of tobacco, so nicotine replacement will not alter it [8].

That distinction matters most at the moment someone quits. In a study of 12 heavy smokers (20 or more cigarettes a day) who stopped abruptly, caffeine clearance, an in-vivo marker of CYP1A2 activity, fell 36.1%, from 2.47 to 1.53 mL/min/kg, with an apparent half-life of decline of 38.6 hours [9]. Quitting smoking can raise blood levels of some CYP1A2 medicines; the same review says dose adjustment is clearly indicated for warfarin, olanzapine, clozapine and theophylline [8].

Where the two overlap: triglycerides and HDL

The Accutane-format label reports marked serum triglyceride elevations in approximately 25% of patients in clinical trials, a decrease in high-density lipoprotein in about 15%, and a rise in cholesterol in about 7%; triglyceride levels above 800 mg/dL have been reported [2]. The label says these effects were reversible on stopping the drug, and that some patients reversed triglyceride elevation with weight reduction, restriction of dietary fat and alcohol, and a lower dose while continuing treatment [2].

Cohort data give a different measure from the trial percentages. In a retrospective cohort of 13,772 patients, the cumulative incidence of a new abnormality in patients with normal baseline values was 44% for triglycerides, 31% for total cholesterol and 11% for transaminases; moderate-to-severe changes were generally transient and reversible [10]. A meta-analysis of 26 studies covering 1,574 patients put mean on-treatment triglycerides at about 120 mg/dL [11].

The labels also warn of acute pancreatitis. The Accutane-format label says it has been reported in patients with either elevated or normal triglycerides, rarely as fatal hemorrhagic pancreatitis, and that the drug should be stopped if hypertriglyceridemia cannot be controlled at an acceptable level [2][1].

The trial data on smoking and lipids concern quitting. In a 1-year randomized trial of smoking-cessation pharmacotherapies that enrolled 1,504 smokers, 334 of the 923 who returned at one year had quit. Their HDL cholesterol rose 2.4 mg/dL against 0.1 mg/dL in continuing smokers (P<.001), despite gaining 4.6 kg versus 0.7 kg, and LDL did not change significantly [12].

Heart, blood vessels and clotting

Nicotine may contribute to cardiovascular disease through hemodynamic effects of sympathetic neural stimulation and systemic catecholamine release. Cigarette smoke also contains many other cardiovascular toxins, and cigarettes deliver nicotine faster and usually in higher doses than replacement products, so the effects are more intense [3]. Smoking increases blood coagulability; transdermal nicotine does not appear to [3]. In trials of nicotine replacement in people with stable coronary disease, nicotine did not appear to raise cardiovascular risk, and at worst the risk from replacement was no greater than that from smoking [3].

Isotretinoin's adverse reaction list includes vascular thrombotic disease, stroke, palpitation and tachycardia, gathered from clinical trials and postmarketing reports in which frequency cannot be reliably estimated [2][1].

Skin and wound healing

Isotretinoin's listed skin reactions include abnormal wound healing (delayed healing, or exuberant granulation tissue with crusting) alongside the dryness, cheilitis and skin fragility that are common on the drug [1][2]. The labels advise avoiding wax epilation and skin resurfacing procedures such as dermabrasion and laser treatment during treatment and for at least 6 months afterward because of scarring [1][2].

Smoking has its own wound-healing signal. A meta-analysis of 140 cohort studies covering 479,150 patients found more healing complications in smokers, with pooled adjusted odds ratios of 2.07 (95% CI 1.53 to 2.81) for healing delay and dehiscence and 1.79 (95% CI 1.57 to 2.04) for surgical site infection [13]. Those figures come from surgical wounds, not from acne treatment.

What the label asks prescribers to check

The Absorica LD label says to complete a fasting lipid profile and liver function tests in all patients before prescribing [1]. The Accutane-format label says lipids should be rechecked at intervals until the lipid response is established, which usually occurs within 4 weeks [2]. It names the patients who need more frequent lipid and blood sugar checks: those with diabetes, obesity, increased alcohol intake, a lipid metabolism disorder, or a family history of one [2]. Smoking is not on that list. Hepatotoxicity is a labeled warning, with liver function tests before and during treatment [1].