Prevention of diazepam-induced thrombophlebitis with cremophor as a solvent

Pharmaceutics for the anaesthetist

Pharmaceutics is that branch of science concerned with the manufacture and formulation of pharmaceutical products, and is a subject almost exclusively in the domain of pharmacists and those concerned with pharmaceutical manufacture. However, there are some aspects of pharmaceutics that are of particular importance to the anaesthetist, such as the pharmacology of the various preservatives, antimicrobials and other additives found in anaesthetic products, and an understanding of basic processes such as emulsification and lyophylisation. This review aims to survey those areas.

"Inactive" ingredients in pharmaceutical products: update (subject review). American Academy of Pediatrics Committee on Drugs

Because of an increasing number of reports of adverse reactions associated with pharmaceutical excipients, in 1985 the Committee on Drugs issued a position statement recommending that the Food and Drug Administration mandate labeling of over-the-counter and prescription formulations to include a qualitative list of inactive ingredients. However, labeling of inactive ingredients remains voluntary. Adverse reactions continue to be reported, although some are no longer considered clinically significant, and other new reactions have emerged. The original statement, therefore, has been updated and its information expanded.

Intravenous vitamin K1 prior to orthotopic heart transplantation: effects in vivo and in vitro

BACKGROUND

Vitamin K1 is used to reverse warfarin's anticoagulant action. It is unclear whether intravenous vitamin K1 is safe or efficacious prior to urgent cardiac surgery.

METHODS

We retrospectively and prospectively examined the effects of preoperative intravenous vitamin K1 in vivo (administered for warfarin reversal immediately before heart transplantation) on intraoperative blood product utilization, hemodynamics and coagulation parameters. We also determined the direct effects of vitamin K1 in vitro on rings of human saphenous vein and internal mammary artery.

RESULTS

In the retrospective limb, 29 of 67 patients were administered vitamin K1 preoperatively via slow intravenous infusion. Vitamin K1 administration produced no adverse outcome but did not affect subsequent perioperative use of blood products. In the prospective limb (n = 10), vitamin K1 significantly (P < or = 0.01, Student t-test) altered mean arterial pressure (from 85 +/- 15 to 76 +/- 16 mmHg), systemic vascular resistance (from 1364 +/- 308 to 1078 +/- 252 dyn.s.cm-5), and cardiac index (from 2.3 +/- 0.3 to 2.7 +/- 0.3 L/min/m2) (mean +/- SD). Significant decreases in prothrombin time (19.8 +/- 2.7 to 17.7 +/- 1.8 s) and activated clotting time (164 +/- 26 to 137 +/- 24 s) were observed at 60 min. In vitro vitamin K1 (10(-7) to 10(-4) M) had no effect on the tone of noradrenaline-constricted rings.

CONCLUSIONS

Vitamin K1, administered by intravenous infusion prior to heart transplantation, did not alter subsequent perioperative blood product administration. Vitamin K1 rapidly reversed the anticoagulant effect of warfarin and produced modest hemodynamic changes. The decrease in systemic vascular resistance is probably not due to a direct effect of vitamin K1 on vascular smooth muscle.

Correlation of delayed peak concentration with infusion-site irritation following diazepam administration

Diazepam 10 mg/2 mL iv was administered undiluted over five minutes to nine healthy men on two separate occasions. The infusion site was evaluated before and after each infusion by subject assessment of pain on a severity scale of zero (none) to ten (most). Blood samples were collected at 0, 5, 20, 30, 45, and 60 minutes, and periodically for 72 hours postinfusion. Diazepam plasma concentrations were determined by HPLC. Concentrations at five minutes (end of infusion) ranged from 0 to 889 ng/mL. Maximum plasma concentration (Cmax) was observed at 5 minutes for 10 treatments, at 20 minutes for 7 treatments, and at 30 minutes for 1 treatment. The observed Cmax ranged from 221 to 889 ng/mL. When time to reach peak plasma concentration (tmax) was 5 minutes, the Cmax was significantly greater than when tmax was 20 minutes (670 +/- 87 vs. 267 +/- 40 ng/mL, p less than 0.005). The area under the curve did not differ significantly between these two groups. The pain score at the end of infusion ranged from zero to five and was inversely related to the concentration at five minutes (r2 = 0.45, p = 0.002). The association between venous irritation, a low plasma concentration at the end of the infusion, and a delayed Cmax suggests that diazepam precipitated in the vein.

Diazepam mixed micelle--comparison with diazepam in propylene glycol and midazolam

A mixed micelle formulation of diazepam was compared with midazolam and diazepam in propylene glycol for evidence of venous intolerance following IV injection. The overall incidence of venous morbidity was 17% for diazepam mixed micelle, 26% for midazolam and 90% for diazepam in propylene glycol. Diazepam mixed micelle is suggested as a preferable alternative to the standard formulation.

Intravenous premedication with diazepam

Two preparations of diazepam, Valium Roche mixed Micelles and Diazemuls, were compared as intravenous premedicants in 119 patients undergoing minor gynaecological surgery. There were no differences between the formulations with regard to anxiolytic effects and systemic tolerance. There were no symptoms typical of thrombophlebitis in the Valium Roche Mixed-Micelles group and only one case in the Diazemuls group. Acute local tolerance was similar with both trial drugs and superior to conventional diazepam preparations. Based on the favourable results of the present study it can be concluded that such vehicles should be considered for any injectable preparation with a known tendency to produce venous irritation.

Intravenous benzodiazepines as anaesthetic agents: pharmacokinetics and clinical consequences

Despite extensive and numerous pharmacokinetic studies on benzodiazepines, the published pharmacokinetic data do not adequately explain the clinical differences found between different benzodiazepine derivatives after intravenous administration. Especially, correlations between initial drug responses and distributional changes of the benzodiazepines are limited. However, during the elimination phase some relationships exist between the kinetic and dynamic phenomena. Age, sex, diseases and concomitantly given drugs cause clinically important alterations in the pharmacokinetics of benzodiazepines. Generally these anxiolytics and sedatives should be considered as adjuvants to general anaesthesia, but not primarily as routine induction agents. The major reasons for this limitation are a high variability in drug response, a relatively slow onset of action and long-lasting residual effects. However, benzodiazepines have many important advantages (see Table 5) when used as intravenous inducing agents of general anaesthesia.

The effect of diazepam on methohexitone short anaesthesia: a clinical double-blind investigation

A double-blind investigation was performed on 113 adult females, hospitalized for short gynaecological procedures, in order to establish the suitability of methohexitone for short procedures and whether or not the quality of methohexitone anaesthesia could be improved with a diazepam supplement. All patients were anaesthetized with methohexitone (2.0 mg/kg): 57 of the patients received a 10 mg diazepam intravenous supplement and 56 received intravenous placebo (solvent of diazepam only). Diazepam injected after induction with methohexitone clearly improved the quality of methohexitone anaesthesia (p less than 0.1 more than 0.05) and reduced the need for supplementary doses of methohexitone (p less than 0.1 more than 0.05). The incidences of both nausea and vomiting were minimized (p less than 0.01 more than 0.001). Patient acceptance was equally good in both groups. It is commented that patients may seem fully awake and oriented, notwithstanding the fact that the body still contains significant amounts of the anaesthetic agent. Ambulatory patients should never be allowed to leave the hospital unescorted, as they recover their 'street-orientation' only after 12 to 24 hours. Furthermore, the patients or their escorts should be given definite and written instructions to avoid absolutely the use of alcohol or hypnotics which could, even in small amounts, potentiate the effect of methohexitone still in the body, for at least 12 hours. It is recommended that patients should avoid driving a motor vehicle or using dangerous tools or machines for 12 to 24 hours following recovery from methohexitone anaesthesia.

Flunitrazepam: a review of its pharmacological properties and therapeutic use

Flunitrazepam is a benzodiazepine derivative whose hypnotic effect predominates over the sedative, anxiolytic, muscle-relaxing and anticonvulsant effects characteristic of benzodiazepines. Thus, it is used as a night-time hypnotic and in anaesthesiology: due to the pronounced hypnotic effect it is not appropriate as a daytime sedative. As a hypnotic for insomnia its effect is usually characterised by a very fast onset of action and quiet sleep without interruptions. On the morning after a hypnotic dose some residual psychomotor impairment does occur, which is comparable to that with usual doses of nitrazepam or flurazepam, but clinically apparent 'hangover' occurs infrequently. There is no pronounced cumulative effect with chronic use. In anaesthesiology it has proven to be useful as a hypnotic on the night before operation, as an oral, intramuscular or intravenous premedication, in induction and as a supplement to other anaesthetics. Its sedative and amnesic properties can also be beneficial in intensive care patients. Much of the usefulness of flunitrazepam in anaesthesia relates to its synergistic effect with other anaesthetics, to its effective amnesic action and its acceptable effects on circulation and respiration. Possible drawbacks include a somewhat unusual course of induction (when used for this purpose) and an often prolonged recovery. Although the safe dosage range is wide with flunitrazepam, its effective application both as a hypnotic for insomnia and in anaesthesiology is dependent upon use of the optimal dosage, and adequate knowledge of its pharmacokinetic properties.

Diazepam-associated thrombophlebitis: a review and discussion of possible prevention

Intravenous diazepam is an excellent anxiolytic drug for dental patients. Thrombophlebitis associated with its use has prompted this review. Recognition and management of thrombophlebitis are discussed along with the causes of vascular injury after intravenous diazepam. In two histologic studies, Graham and others thought it unlikely that precipitated crystals of diluted diazepam caused postinjection vasculopathology. It seems to be an inherent property of the vehicle or the drug itself. The reviewed methods of minimizing thrombophlebitis after intravenous diazepam are with hepari flush or saline solution flush, steroids, vein size and venipuncture site, the use of a different vehicle, dilutions, and the use of other benzodiazepines. Lorazepam, midazolam, and flunitrazepam are relatively new benzodiazepines that produce less thrombophlebitis than diazepam after injection. These newer benzodiazepines are still being investigated and more clinical trials must be done to recommend any of them as alternatives to intravenous diazepam in dentistry.

Venous complications after intravenous injection of diazepam, flunitrazepam, thiopentone and etomidate

The occurrence of phlebitis, thrombosis, and thrombophlebitis after intravenous premedication with diazepam (0.15 mg/kg) dissolved in propylene glycol (Valium) or in polyethylene glycol (Diapam) or flunitrazepam (0.0125 mg/kg), and after intravenous induction of balanced general anaesthesia with thiopentone (4.0 mg/kg) or etomidate (0.3 mg/kg) was studied on the 7th and 14th postoperative days in 115 patients undergoing short-stay varicose vein surgery. Venous complications occurred most frequently after etomidate (43% at 14 days), thiopentone (23% at 14 days), and Valium (21% at 7 days). Diapam caused fewer venous sequelae (9% at 14 days) than Valium (18% at 14 days), but the smallest number of complications were noticed after flunitrazepam (8% at 7 days and none at 14 days). Venous sequelae were more severe and more extended after thiopentone and after etomidate than those after the diazepam preparations. It is concluded that venous complications after flunitrazepam premedication were mild and infrequent and that the incidence of such complications was unacceptably high after etomidate induction.