A critical examination of the mode of action of quinacrine in the reproductive tract in a 2-year rat cancer bioassay and its implications for human clinical use

What happened to quinacrine non-surgical female sterilization?

Quinacrine sterilization (QS) is a nonsurgical female method used by more than 175,000 women in over 50 countries. With FDA approval, QS is expected to be used by hundreds of millions of women. The negative international health consequences of the results of a 2-year rat study in 2010 by Cancel et al. in Regulatory Toxicology and Pharmacology (RTP) (56:156-165) are incalculable. S1C(R2) was ignored in this study, including the fundamental concept of maximum tolerated dose (MTD), which resulted in the use of massive doses (up to 35 times the MTD) which killed many of the rats and destroyed the uterus of survivors. The design of this rat study was built on the false assertion that this study mimics what happens in women. Cancel et al. (2010), concludes it "seems most likely" that genotoxicity was a major factor in the carcinogenicity observed, prompting the FDA to halt further research of QS. In RTP, McConnell et al. (2010), and Haseman et al. (2015), using the authors' data, definitively determined the carcinogenicity to be secondary to necrosis and chronic inflammation. Decisions made in the design, conduct, analysis, interpretation and reporting in this study lack scientific foundation. This paper explores these decisions.

Long-term risk of hysterectomy and ectopic pregnancy among Vietnamese women using the quinacrine hydrochloride pellet system vs. intrauterine devices or tubal ligation for contraception

OBJECTIVES

Determine the long-term risk of hysterectomy and ectopic pregnancy in women using the quinacrine hydrochloride pellet system of permanent contraception (QS) relative to the comparable risk in women using Copper T intrauterine device (IUD) or tubal ligation surgery (TL) for long-term or permanent contraception.

METHODS

This was a retrospective cohort study, conducted in the Northern Vietnamese provinces of Ha Nam, Nam Dinh, Ninh Binh and Thai Binh. Women who had their first QS procedure, last IUD insertion or TL between 1989 and 1996 were interviewed regarding post-procedure health outcomes approximately 16 years post exposure.

RESULTS

A 95% response rate resulted in 21,040 completed interviews. Overall incidence rates were low for both outcomes (91/100,000 women years of follow-up and 22/100,000 women years of follow-up for hysterectomy and ectopic pregnancy, respectively). After accounting for variations in baseline characteristics between women choosing QS vs. the other two contraceptive methods, no significant excess hazard of either hysterectomy or ectopic pregnancy was associated with QS.

CONCLUSIONS

No significant excess long-term risk of hysterectomy or ectopic pregnancy was found among a large group of women using QS vs. IUD or TL for contraception after an average 16 years of follow-up.

Quinacrine pretreatment reduces microwave-induced neuronal damage by stabilizing the cell membrane

Quinacrine, widely used to treat parasitic diseases, binds to cell membranes. We previously found that quinacrine pretreatment reduced microwave radiation damage in rat hippocampal neurons, but the molecular mechanism remains poorly understood. Considering the thermal effects of microwave radiation and the protective effects of quinacrine on heat damage in cells, we hypothesized that quinacrine would prevent microwave radiation damage to cells in a mechanism associated with cell membrane stability. To test this, we used retinoic acid to induce PC12 cells to differentiate into neuron-like cells. We then pretreated the neurons with quinacrine (20 and 40 mM) and irradiated them with 50 mW/cm² microwaves for 3 or 6 hours. Flow cytometry, atomic force microscopy and western blot assays revealed that irradiated cells pretreated with quinacrine showed markedly less apoptosis, necrosis, and membrane damage, and greater expression of heat shock protein 70, than cells exposed to microwave irradiation alone. These results suggest that quinacrine stabilizes the neuronal membrane structure by upregulating the expression of heat shock protein 70, thus reducing neuronal injury caused by microwave radiation.

Long-term risk of reproductive cancer among Vietnamese women using the quinacrine hydrochloride pellet system vs. intrauterine devices or tubal ligation for contraception

OBJECTIVES

To determine the long-term risk of reproductive tract cancer in women using the quinacrine hydrochloride pellet system of permanent contraception (QS) relative to the comparable risk in women using Copper T intrauterine device (IUD) or tubal ligation surgery (TL) for long-term or permanent contraception.

METHODS

This was a retrospective cohort study, conducted in the Northern Vietnamese provinces of Ha Nam, Nam Dinh, Ninh Binh and Thai Binh. Women who had their first QS procedure, last IUD insertion or TL between 1989 and 1996 were interviewed regarding post-procedure health outcomes, particularly reproductive tract cancers.

RESULTS

A 95% response rate resulted in 21,040 completed interviews. Reproductive cancer incidence rates were very low (5.77/100,000 women years of follow-up time; 95%CI = 3.72-8.94). No significant excess hazard of reproductive tract cancer was associated with QS.

CONCLUSIONS

No significant excess long-term risk of reproductive tract cancer was found after an average 16 years of follow-up among a large group of women using QS vs. IUD/TL for contraception.

Quinacrine sterilization (QS): time for reconsideration

Dr. Jaime Zipper, the Chilean inventor of the quinacrine method of nonsurgical permanent contraception, was aware that when chest surgeons injected quinacrine into the pleural cavity to treat and prevent reoccurrence of pleural effusion, it resulted in the formation of fibrous adhesions between the lung and costal pleura. Zipper thought that a similar scarring effect could occur in the fallopian tubes if quinacrine was instilled into the uterine cavity. A series of refinements of the methodology culminated in the use of a modified Copper T intrauterine device inserter tube as a delivery system to introduce seven quinacrine pellets into the uterus. This approach with quinacrine sterilization (QS) was introduced into clinical practice in several countries, and a national clinical trial of over 50,000 women was conducted in Vietnam. However, in 1993, the World Health Organization raised concerns that quinacrine might be carcinogenic. This resulted in abandonment of QS in Vietnam and other countries. Subsequent epidemiologic data from extensive human studies do not support an increase in cancer risk. This paper reviews the history, limitations and clinical potential of QS.