Background: Efavirenz, an anti-HIV agent, has a noticeable place in the HAART regimen for the treatment and maintenance therapy of AIDS. However, its poor water solubility accounts for hindered absorption and bio-distribution upon administration. This results in its low and variable bioavailability. To circumvent these limitations, various novel formulations of Efavirenz have been investigated in order to mitigate its drawbacks and draw out its maximum therapeutic effect.

Methods: Numerous formulations explored to overcome the drawbacks of Efavirenz include modified/ controlled-release tablets, solid dispersions, polymeric nanoparticles, dendrimers, surface-engineered nanoparticles and various other nanoformulations. Moreover, combinatorial formulations of Efavirenz with other Anti-HIV drugs have also been reported to overcome the problem of Drug-Resistance.

Results: The nanoformulation based strategies, owing to their ability to provide controlled release profile and targeted drug delivery were found to augment bioavailability, therapeutic efficacy and reduce the side effects of the Efavirenz.

Conclusion: This review pivots around the challenges and recent advances in the delivery of Efavirenz with particular emphasis on novel formulations including its patents.

背景：抗艾滋病毒药物依非韦伦茨（Efavirenz）在HAART疗法中具有显着的地位，可用于艾滋病的治疗和维持治疗。然而，其不良的水溶性导致给药后吸收和生物分布受阻。这导致其生物利用度低且可变。为了规避这些限制，已经研究了依非韦伦的各种新颖制剂，以减轻其缺点并发挥其最大的治疗作用。

方法：为克服依法韦仑的缺点而探索的许多制剂包括改良/控释片剂，固体分散体，聚合物纳米颗粒，树枝状聚合物，表面工程纳米颗粒和各种其他纳米制剂。此外，据报道依非韦伦与其他抗艾滋病毒药物的组合制剂克服了抗药性的问题。

结果：基于纳米制剂的策略，由于其提供控释特性和靶向药物递送的能力，被发现可以提高生物利用度，治疗功效并减少依夫韦仑的副作用。

结论：这篇综述围绕着依非韦伦的交付中所面临的挑战和最新进展，其中特别强调了包括其专利在内的新型制剂。