It has been hypothesized that besides its intraocular pressure (IOP) lowering potential, tetrahydrocannabinol (THC) may also improve ocular hemodynamics. The aim of the present study was to investigate whether single oral administration of dronabinol, a synthetic THC, alters optic nerve head blood flow (ONHBF) and its regulation in healthy subjects. The study was carried out in a randomized, placebo‐controlled, double‐masked, two‐way crossover design in 24 healthy subjects. For each study participant, 2 study days were scheduled, on which they either received capsules containing 5 mg dronabinol or placebo. ONHBF was measured with laser Doppler flowmetry at rest and while the study participants performed isometric exercise for 6 minutes to increase mean arterial blood pressure (MAP). This was repeated 1 hour after drug intake. Ocular perfusion pressure (OPP) was calculated as 2/3MAP–IOP. Dronabinol was well tolerated and no cannabinoid‐related psychoactive effects were reported. Neither administration of dronabinol nor placebo had an effect on IOP, MAP, or OPP. In contrast, dronabinol significantly increased ONHBF at rest by 9.5 ± 8.1%, whereas placebo did not show a change in ONHBF (0.3 ± 7.4% vs. baseline, P  < 0.001 between study days). Dronabinol did not alter the autoregulatory response of ONHBF to isometric exercise. In conclusion, the present data indicate that low‐dose dronabinol increases ONHBF in healthy subjects without affecting IOP, OPP, or inducing psychoactive side effects. In addition, dronabinol does not alter the autoregulatory response of ONHBF to an experimental increase in OPP. Further studies are needed to investigate whether this effect can also be observed in patients with glaucoma.

中文翻译：

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口服屈大麻酚对健康受试者视神经头血流的影响——一项随机临床试验。

据推测，四氢大麻酚（THC）除了具有降低眼压（IOP）的潜力外，还可以改善眼部血流动力学。本研究的目的是调查单次口服屈大麻酚（一种合成 THC）是否会改变健康受试者的视神经乳头血流量（ONHBF）及其调节。该研究以随机、安慰剂对照、双盲、双向交叉设计的方式在 24 名健康受试者中进行。对于每位研究参与者，安排了 2 天的研究，期间他们要么服用含有 5 毫克屈大麻酚的胶囊，要么服用安慰剂。ONHBF 是在休息时用激光多普勒血流计测量的，同时研究参与者进行 6 分钟的等长运动以增加平均动脉血压 (MAP)。服药后1小时重复此操作。眼灌注压 (OPP) 计算为 2/3MAP-IOP。屈大麻酚的耐受性良好，没有报道大麻素相关的精神影响。给予屈大麻酚和安慰剂均对 IOP、MAP 或 OPP 没有影响。相比之下，屈大麻酚使静息时 ONHBF 显着增加 9.5 ± 8.1%，而安慰剂未显示 ONHBF 变化（与基线相比为 0.3 ± 7.4%， 研究日之间P < 0.001）。屈大麻酚不会改变 ONHBF 对等长运动的自动调节反应。总之，目前的数据表明，低剂量屈大麻酚可增加健康受试者的 ONHBF，而不影响 IOP、OPP 或诱发精神副作用。此外，屈大麻酚不会改变 ONHBF 对 OPP 实验性增加的自动调节反应。需要进一步的研究来调查这种效应是否也可以在青光眼患者中观察到。